British Journal of Anaesthesia

Background One in four surgical patients carries a drug allergy label, of which an estimated 90% are incorrect. Avoidance of first-choice drug therapies may lead to worse postoperative outcomes. We sought to determine the nature and extent of any association between drug allergy labels and postoperative complications. Methods A multicentre observational study in 21 NHS hospitals. Eligible patients were 18 years or older, undergoing common surgical procedures: primary hip or knee replacement; internal fixation of closed long bone fracture; colorectal resection; trans-urethral resection of prostate or bladder tumour; caesarean section; hysterectomy. Exclusion criteria: use of antibiotics in the two weeks prior to surgery, previous participation in the study. Primary outcome was postoperative complications within 30 days following surgery, a composite outcome comprising: all postoperative infections, anastomotic leak, acute respiratory distress syndrome, myocardial infarction, postoperative bleed, pulmonary embolism, stroke, antimicrobial side effects, death. Results Among 13,646 patients, 3924 (29%) carried greater than or equal to1 drug allergy labels. Labelled patients were more likely to develop postoperative complications (989/3924 (25%) vs 1926/9722 (20%); OR 1.21 [1.10-1.34]; p<0.001). They were more likely to develop surgical site infections (337/3924 (9%) vs 760/9722 (8%); OR 1.19 [1.03 -1.38]; p<0.018), and any postoperative infection (750/3924 (19%) vs 1472/9722 (15%); OR 1.24 [1.11-1.38] p<0.001). Labelled patients experienced increased risk of allergic drug reactions (31/3924 (0.01%) vs 29/9722 (<0.01%); OR 3.00 [1.77-5.09]; p<0.001), but no increase in mortality. Conclusions Drug allergy labels are common, but often incorrect. Labelled patients experience worse postoperative outcomes, including infective and non-infective complications and increased risk of allergic drug reactions. Trial registration Registered with ISRCTN registry, ISRCTN15775657.

BackgroundNon-steroidal anti-inflammatory drugs (NSAIDs) and weak opioids such as tramadol are cornerstones of multimodal analgesia, particu-larly in settings with limited access to potent opioids. However, cross-class equianalgesic data comparing these agents remain scarce. This pilot ran-domised controlled trial aimed to explore the analgesic equivalence of ke-torolac, diclofenac, and tramadol administered as premedication in patients undergoing minimally invasive surgery. MethodsIn this double-blind, parallel-group pilot trial, 30 patients scheduled for elective minimally invasive surgery (28 laparoscopic cholecys-tectomies, 2 laparoscopic abdominal wall repairs) under balanced general anaesthesia were randomised to receive intravenous tramadol 150 mg, ke-torolac 60 mg, or diclofenac 150 mg 45 minutes before skin incision. The primary outcome was pain intensity measured using the Numerical Rating Scale (NRS, 0-10) at recovery room arrival (T0) and at 30 (T1), 60 (T2), and 90 (T3) minutes thereafter. Secondary outcomes included Verbal Rating Scale (VRS) scores, rescue morphine consumption, and safety. Between-group comparisons were performed using Kruskal-Wallis tests with Dunn post-hoc corrections; within-group trajectories were analysed using Fried-man tests. Effect sizes were estimated with epsilon-squared and Kendalls W. ResultsAll 30 patients completed the study. At T0 and T1, NRS scores were higher in the ketorolac group (median 1.5 and 3, respectively) compared with tramadol and diclofenac (both median 0 at T0; T1: tramadol 1, diclofenac 2; p < 0.05 for both). However, by T2 and T3, all three groups converged to a median NRS of 2 (p > 0.05 for between-group differences). Rescue analgesia requirements at T1 were 0/10 (tramadol), 3/10 (ketorolac), and 2/10 (diclofenac), with no statistically significant differences (p = 0.19). No hypersensitivity reactions occurred. Within-group analyses showed con-sistent pain trajectories, with Kendalls W ranging from 0.31 (ketorolac) to 0.64 (tramadol). ConclusionsIn this pilot study, equianalgesic doses of tramadol, ke-torolac, and diclofenac provided comparable postoperative pain control over 90 minutes following minimally invasive surgery. All agents were well toler-ated. These findings support the feasibility of a larger definitive trial and offer clinically useful guidance for analgesic selection in resource-limited settings. Trial registrationClinicalTrials.gov - NCT07500454 (retrospectively registered). HighlightsO_LIDouble-blind pilot RCT compared equianalgesic doses of tramadol, ke-torolac, and diclofenac. C_LIO_LIAll three groups converged to median NRS 2 by 60 minutes postoper-atively. C_LIO_LIEarly higher pain in the ketorolac group was partly attributed to age imbalance ({rho}=0.49, p=0.006). C_LIO_LINo hypersensitivity reactions occurred in any group. C_LIO_LIDefinitive trial requires 27 patients per group (90 total with 10% attri-tion). C_LI

Background Informed consent depends on patients' understanding of anaesthesia risk, yet comprehension remains poor despite routine preoperative consultation. Conversational artificial intelligence (AI) could establish patient-reported understanding before clinician contact, but whether such systems can achieve patient-reported understanding comparable to clinician-delivered education remains unknown. Methods We conducted a randomised equivalence trial (n = 130) of PEAR (Preoperative Education of Anaesthesia Risks), a multilingual retrieval-augmented conversational AI grounded in institutional consent materials, versus standard preoperative consultation in adults undergoing elective surgery. Results A total of 130 adults (mean age 52.4 +/- 14.5 years) were enrolled. Post-consultation understanding scores in the PEAR group met the pre-specified equivalence criterion compared with standard consultation across all three primary measures. Patients who interacted with PEAR before clinician contact achieved understanding scores comparable to those receiving standard face-to-face consultation alone. PEAR reduced documentation and consultation time, corresponding to a projected annual net benefit of approximately SGD 0.99 million (USD 0.78 million) at a single tertiary centre. Conclusions A retrieval-augmented conversational AI achieved patient-reported understanding of anaesthesia risk equivalent to standard preoperative consultation while substantially improving workflow efficiency. These findings support supervised deployment of conversational AI within perioperative care pathways while preserving clinician oversight for verification and patient-specific decision-making.

Abstract Background: Acute postoperative pain affects more than 80% of surgical patients, with orthopedic lower limb procedures consistently associated with severe pain intensity and high opioid requirements. Preemptive analgesia with oral agents has been proposed to attenuate central and peripheral sensitization prior to surgical incision. Tapentadol, a dual-mechanism -opioid receptor agonist and norepinephrine reuptake inhibitor, and pregabalin, a voltage-gated calcium channel modulator, represent pharmacologically distinct premedication options; however, direct comparative data in this surgical context are lacking. This pilot randomized controlled trial aimed to compare the analgesic efficacy and safety of 72-hour oral premedication with tapentadol versus pregabalin in patients undergoing elective lower limb surgery under neuraxial anesthesia. Methods: In this double-blind, parallel-group pilot trial, 46 patients scheduled for elective lower limb surgery under neuraxial anesthesia were randomized equally to receive tapentadol 50mg orally every 12 hours (Group A, n = 23) or pregabalin 75mg orally every 24 hours (Group B, n = 23), initiated 72 hours before surgical incision. The primary outcome was postoperative pain intensity assessed using the Numeric Rating Scale (NRS, 0-10) at post-anesthesia care unit (PACU) arrival (T0) and at 30 (T1), 60 (T2), 90 (T3), and 120 (T4) minutes thereafter. Secondary outcomes included Verbal Rating Scale (VRS) scores, rescue morphine consumption, and safety. The primary longitudinal analysis used a linear mixed model (LMM) with Group, Time, and Group x Time interaction as fixed effects and a random intercept per patient; between-group contrasts at each timepoint were derived from estimated marginal means with Holm correction. Effect sizes are reported as Cohen's d. Results: All 46 patients completed the study with no missing data. Both groups were pain-free at T0 (NRS=0). Pain scores diverged progressively from T1 onward, with the pregabalin group reporting consistently higher NRS values at every time point. The LMM revealed a significant main effect of Time (F4,181.6 = 23.61, p < 0.001) and a borderline-significant Group x Time interaction in the continuous-time sensitivity model (F1,187.6 = 3.79, p = 0.053). Post-hoc contrasts identified a statistically significant, large effect between-group difference at T3 (mean NRS difference -0.91, p = 0.006, Cohen's d = -0.96) and a medium-effect trend at T2 (d = -0.59, p = 0.089). Rescue analgesia was required by 4.3% of tapentadol patients versus 21.7% of pregabalin patients. Nausea and vomiting were equally present in both groups (17.4%). No hypersensitivity reactions were observed in either arm. Conclusions: Seventy-two-hour oral premedication with tapentadol 100mg/day provided superior postoperative analgesia compared with pregabalin 75 mg/day at the 90-minute PACU time point, with a large effect size and a fivefold reduction in rescue analgesia requirements. Both agents were well tolerated. These pilot data support the conduct of a fully powered, multicenter randomized controlled trial to confirm the analgesic superiority of tapentadol premedication in orthopedic lower limb surgery.

Background Virtual Hospital (VH) pathways enable early discharge and are promoted across the NHS. However, evidence supporting their safety, effectiveness, equity, and patient acceptability in elective colorectal surgery remains limited. Objective To evaluate implementation of a VH pathway following elective colorectal surgery and its impact on clinical outcomes, patient-centred recovery, and equality, diversity and inclusion (EDI). Design Retrospective service evaluation with a historical comparator. A 1:1 propensity-matched analysis was performed in colorectal cancer patients using age, sex, body mass index, ASA grade, Charlson Comorbidity Index, procedure type, tumour site, and anastomosis. Setting West Hertfordshire Teaching Hospitals NHS Trust. Patients Patients undergoing elective colorectal surgery between November 2023 and March 2025 managed via a VH pathway, compared with a non-VH cohort. Main outcome measures Primary outcomes were inpatient length of stay (IPLOS), VH length of stay (VHLOS), and days alive and at home within 30 days (DAH30). Secondary outcomes were patient-reported experience and EDI characteristics. Results Eighty-one patients were managed via VH. Median [Q1 - Q3] IPLOS was 2 [1 - 2] days and VHLOS was 2 [2 - 3] days, with no deaths. Forty-two colorectal cancer patients were propensity matched 1:1 to a pre-VH cohort. IPLOS was shorter in the VH cohort (2 [1 - 2] vs 4 [3 - 5] days; p<0.001), and DAH30 was higher (28 [28 - 29] vs 25.5 [24 - 27] days; p<0.0001). Patient experience was positive, with mean satisfaction >8.5/10 and over 90% preferring VH-supported recovery. Sex and ethnicity distributions were similar, although VH patients were younger (p=0.028). Limitations This single-centre retrospective evaluation had a modest sample size and non-randomised design. VH patients were carefully selected, limiting generalisability. Conclusions A VH pathway following elective colorectal surgery is feasible, safe, and acceptable. Compared with a pre-VH cohort, VH care reduced inpatient stay and improved patient-centred recovery without compromising safety.

Background: Perioperative pain management modality potentially influences psychiatric morbidity and healthcare utilization. The opioids have been most commonly used for managing postoperative pain and carry a high degree of risk for creating mood disorders, anxiety, sleep disturbances, and healthcare burdens. A novel non-opioid analgesic, Suzetrigine, may be able to effectively manage postoperative pain without some of the psychological and economic risks that come from the use of opioids. In this study, we measured psychiatric outcomes and emergency department (ED) usage among postoperative patients who received either suzetrigine or opioids. Methods: This was a retrospective cohort study using the TriNetX US Collaborative Network, encompassing 64 healthcare organizations. Adult patients (> Age 18 years) who underwent surgery and received suzetrigine were compared with patients who underwent surgery and received opioids. Propensity score matching (1:1) performed to match cohorts based on demographic factors (age, gender, racial/ethnic status), social determinants of health (ICD-10 Z55-Z65), family histories of substance abuse and psychiatric disorders (Z81.x), surrogate measures of prior healthcare utilization, and pre-existing clinical severity using Elixhauser-Charlson comorbidity proxies (hypertensive diseases [I10-I15], diabetes mellitus [E08-E13], ischemic heart disease [I22-I25], and chronic pulmonary disease [J42-J47]). Matching also included behavioral risk factors (tobacco use and physical inactivity) and body mass index (BMI). Following matching, there were 2,221 patients in each cohort. The primary outcome assessed within one year after surgery was ED utilization, depression, anxiety, post-traumatic stress disorder (PTSD) and sleep disorders. Risk estimates and survival analyses were used to compare the outcomes. Results: In propensity-matched analyses, suzetrigine use was associated with a reduction in multiple psychiatric outcomes and healthcare utilization compared to opioid analgesics. There was less ED utilization in the suzetrigine cohort (5.9% v 13.1%, RR 0.45, p< .001). The psychiatric outcomes were also lower in the suzetrigine cohort than the opioid cohort, including depression (3.1% v 4.7%, RR 0.65, p= .005), anxiety (4.7% v 7.2%, RR 0.65, p< .001), PTSD (0.5% v 1.4%, RR 0.36, p= .002), and sleep disorders (4.2% v 6.0%, RR 0.71, p= .008). The survival analysis suggested an earlier onset of psychiatric diagnosis among the opioid recipients. Conclusion: In a matched real-world cohort of surgical patients, suzetrigine use was associated with lower short-term rates of selected postoperative outcomes compared with opioid analgesics. Keywords: Suzetrigine; Opioid-Sparing; Analgesia; Postoperative Outcomes; Cohort Study

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic multisystem disease characterized by profound fatigue, post-exertional malaise, cognitive impairment, and autonomic dysfunction. Its pathophysiology is incompletely understood and likely involves complex interactions between immune, autonomic, and metabolic dysregulation. Despite features with potential relevance for anesthesia and perioperative care, evidence to guide anesthetic management in individuals with ME/CFS remains limited. We therefore performed a retrospective matched-pair analysis to generate clinical data on perioperative responses and identify areas for future research. Methods: We conducted a retrospective matched-pair analysis at a single tertiary center. All patients with ME/CFS undergoing general anesthesia from 2015 to 2026 were identified using ICD-10 codes (G93.3 and U09.9) with additional manual verification and matched 1:1 to controls for comparison. Patients with confounding diagnoses or American Society of Anesthesiologists physical status above III were excluded. The analysis focused on intraoperative hemodynamic parameters, including baseline, post-induction, median, and lowest recorded systolic blood pressure and heart rate, as well as early postoperative outcomes in the post-anesthesia care unit (PACU), including maximum pain scores and requirement for rescue analgesia. Results: Out of 189 individuals identified through ICD-10 codes, 15 matched pairs were included after application of exclusion criteria. ME/CFS patients exhibited lower lowest recorded intraoperative systolic blood pressure (90 [82.5-95.0] mmHg in ME/CFS vs 100 [90.0-110.0] mmHg in controls, p = 0.044) as well as lower lowest heart rate (50 [40.0-57.5] bpm in ME/CFS vs 60 [50.0-65.0] bpm in controls, p = 0.012). Vasopressor use and fluid administration did not differ, and no episodes of severe hypotension or perioperative adverse events were observed. Postoperative pain was higher in ME/CFS, with higher maximum pain scores (NRS 5.0 [4.0-6.0] in ME/CFS vs 1.0 [0.0-4.0] in controls, p = 0.008) and more frequent opioid rescue analgesia (80% in ME/CFS vs 33% in controls, p = 0.039). Postoperative nausea or vomiting, oxygen supplementation, and PACU length of stay were similar between groups. Conclusions: General anesthesia appears hemodynamically well tolerated in individuals with ME/CFS. In contrast, postoperative pain burden is increased and may require tailored analgesic strategies. Post-exertional malaise, a key disease feature with potentially delayed onset and significant impact, was not captured in this study and remains an important target for future research. These hypothesis-generating findings highlight the need for prospective studies to optimize perioperative management and evaluate patient-relevant outcomes in ME/CFS.

BackgroundThe transition from acute to chronic pain represents a failure of physiological resolution. While systemic immune cell counts and androgen levels have been associated with this transition, the specific molecular mediators remain poorly understood. We sought to identify the functional proteomic drivers of long-term pain persistence and determine their independence from systemic factors. MethodsWe identified a longitudinal persistence cohort (N=3,221) within the UK Biobank who reported acute pain at baseline and were followed for resolution or persistence. Using the Olink Explore 3072 platform, we screened 2,923 serum proteins. Multivariable competition models were employed to evaluate the independent predictive power of top proteomic hits alongside systemic monocyte counts and circulating free testosterone levels, adjusted for age and sex. ResultsOur proteome-wide screen identified Lactoperoxidase (LPO) as a dominant and highly significant predictor of pain persistence. In the fully adjusted competition model, each standard deviation increase in LPO was associated with a 59% increase in the odds of persistence (OR 1.59, 95% CI 1.25-2.07, p < 0.001). Notably, after accounting for LPO, systemic monocyte counts (OR 0.93, p = 0.55) and testosterone levels (OR 0.82, p = 0.46) were no longer significant predictors. Nogo Receptor (RTN4R) also remained a significant predictor in independent models (OR 1.44, p = 0.002). ConclusionsThese exploratory findings demonstrate that long-term pain persistence is associated with specific functional molecular signatures rather than broad systemic cell quantity. The dominance of LPO suggests that secretory peroxidase-driven pathways may be a primary barrier to pain resolution. Furthermore, the association of RTN4R identifies neural repair inhibition as a candidate driver of persistence. These proteins are candidates for further mechanistic investigation.

Background Social disconnection has emerged as a major public health concern, with health risks comparable to established biomedical factors. At the same time, pain remains the leading cause of years lived with disability worldwide, imposing profound individual and societal costs. Although social factors are increasingly implicated in pain perception and chronification, existing evidence is fragmented across heterogeneous and often conflated constructs of social connectedness. It remains unclear whether subjective experiences such as loneliness or structural factors such as social isolation differentially relate to pain outcomes. A comprehensive synthesis directly comparing these dimensions has been lacking. Methods We conducted a preregistered multivariate meta-analysis (PROSPERO: CRD420250643896) including 239 studies, 520 effect sizes, and 1,407,803 participants from clinical and non-clinical populations. Pain outcomes encompassed sensory, affective, cognitive, and functional domains. Social connectedness was operationalized as loneliness, social isolation, social support, and social exclusion. Multilevel random-effects models accounted for within-study dependency, with extensive sensitivity analyses and correction for small-study bias. Results Across populations and social outcomes, greater social connectedness was associated with lower pain (z = -0.09, 95% CI -0.11 to -0.07). Notably, loneliness emerged as the strongest correlate (z = 0.14, 95% CI 0.11 to 0.17). Associations with social isolation were smaller compared to loneliness but were also significant (z = 0.09, 95% CI 0.05 to 0.13). Social support showed modest, significant inverse associations (z = -0.05, 95% CI -0.08 to -0.03), primarily confined to affective and somatic pain components. No reliable association was observed for social exclusion. Associations were consistent across age, sex, and clinical status, and longitudinal evidence supported temporal links between changes in social connectedness and subsequent pain outcomes. Conclusions This large-scale synthesis identifies subjective social disconnection, particularly loneliness, as a robust correlate of pain across populations and pain dimensions, exceeding the relevance of objective social isolation. Given evidence linking loneliness to increased analgesic and psychotropic medication use, social disconnection may contribute to pharmacological burden and polypharmacy risk in vulnerable populations. Social connectedness emerges as a clinically meaningful, non-pharmacological determinant of pain and a potential target for integrative pain prevention and management strategies.

Introduction: Acute low back pain is a leading cause of disability worldwide. Clinical guidelines recommend non-pharmacological therapies as first-line treatment and advise caution with opioid prescribing. However pharmacological therapies, including opioids and gabapentinoids, remain commonly used. The comparative risks of subsequent opioid use disorder (OUD) and overdose diagnosis associated with initial treatment modality in large, real-world populations is not well characterized. We estimated the incidence of new-onset OUD and overdose diagnosis among opioid-naive, Medicaid-insured adults with newly diagnosed acute low back pain and estimated the association between initial treatment modalities and subsequent OUD and overdose diagnosis risk. Methods: We conducted a retrospective cohort study using Medicaid T-MSIS Analytic files from 25 states (2016-2019). We identified opioid-naive adults with a new diagnosis of acute low back pain who initiated pharmacologic or non-pharmacologic treatment within 1 month of diagnosis. The primary outcome was incident OUD and overdose diagnosis (based on diagnosis codes in claims) during follow-up. Associations between initial treatment modality and OUD and overdose diagnosis risk were estimated using a non-parametric, doubly robust estimator to adjust for measured confounding. Results: The cohort included 525,002 opioid-naive adults initiating treatment for low back pain. The cumulative incidence of OUD and overdose diagnosis was 1.5% and 2.4% at 7 and 13 months, respectively. Compared to non-use, use of gabapentinoids during the first month of treatment was associated with the highest relative risk (increasing risk) by 130.1%, 95% confidence interval (CI): 117.8%, 142.3%), the second-highest relative risk was estimated for higher-dose opioids, defined as > 50 daily Morphine Milligram Equivalents (MME) (118.1%, 95% CI: 99.2%, 137.0%). Lower-dose, short-duration opioids ([&le;] 50 MME, [&le;] 7 days) were also associated with elevated risk, though substantially smaller in magnitude (20.8%, 95% CI: 13.8%, 27.9%). In contrast, non-pharmacologic, non-interventional therapies were associated with reduced OUD and overdose diagnosis risk, with physical therapy demonstrating the largest relative reduction of 34.0% (95% CI: -40.9%, -27.1%). Discussion: In opioid-naive Medicaid patients with acute low back pain, initial non-pharmacologic treatment was associated with reduced OUD and overdose diagnosis risk. Gabapentinoids and opioids were each associated with increased risk; for opioids, the degree of risk increased with higher doses and durations. These results support guideline recommendations favoring non-pharmacologic treatment as first-line therapy and indicate the importance of cautious prescribing when pharmacologic treatment is considered.

Background: Post-dural puncture headache (PDPH) affects up to 11.2% of patients after neuraxial anesthesia. The sphenopalatine ganglion block (SPGB) is a promising minimally invasive intervention, but high-quality randomized trial data are limited. We conducted a pilot randomized controlled trial to assess feasibility and inform a future definitive trial. Methods: Twenty-six patients with PDPH following accidental dural puncture with 17G Tuohy needles were randomized to conservative management (bed rest, hydration) or SPGB (bilateral intranasal 2% lidocaine). Primary outcomes were feasibility (recruitment, retention, protocol adherence). Secondary outcomes included pain intensity (Numeric Rating Scale, NRS 0-10) at 30 minutes, 12 hours, and 24 hours; rescue analgesia requirements; mobilization time; and adverse events. Results: Feasibility was confirmed: 100% recruitment of target sample, 100% retention, 100% protocol adherence. At 30 minutes, all SPGB patients reported complete pain resolution (NRS=0) versus median NRS 3 (IQR 2) in controls (p<0.001), though this finding is limited by lack of blinding and baseline assessment. No SPGB patients required rescue analgesia or experienced adverse events. Conservative group patients had prolonged hospitalization (46%). Sample size calculation for a definitive trial (90% power, =0.05) yields 120 participants (60/group). Conclusions: A definitive RCT comparing SPGB to conservative management for PDPH is feasible. Preliminary efficacy data suggest rapid analgesia with SPGB, but rigorous confirmation in a sham-controlled trial is required. Trial registration: ClinicalTrials.gov -NCT07494383 (retrospectively registered). Keywords: Post-dural puncture headache, sphenopalatine ganglion block, pilot study, feasibility, regional anesthesia, randomized controlled trial

ObjectiveTo conduct de novo meta-analyses quantifying the association of five biopsychosocial risk factor domains with chronic pain or related treatment outcomes, and to construct a composite risk index with formal uncertainty propagation for interventional pain medicine. MethodsUmbrella review with de novo random-effects meta-analyses (DerSimonian-Laird and REML with Knapp-Hartung adjustment) across PubMed/MEDLINE, Scopus, and the Cochrane Library through March 2026. Five risk factor domains were evaluated: (1) sleep disturbance, (2) pain catastrophizing, (3) metabolic/obesity, (4) preoperative opioid exposure, and (5) benzodiazepine co-prescription. Publication bias was assessed via Eggers test and PET-PEESE regression. Primary study overlap was quantified using the Corrected Covered Area (CCA). We constructed a primary three-domain composite (sleep, catastrophizing, metabolic) and a secondary expanded six-domain composite (adding opioid, BZD, smoking), using the logistic link function with binary risk factor inputs (present/absent); composite score 95% confidence intervals were computed via delta method variance propagation. Risk of bias of the composite was assessed using PROBAST [Wolff RF et al., Ann Intern Med 2019]; TRIPOD+AI compliance is reported in Supplementary S6 [Collins GS et al., BMJ 2024]. Reviewer process (per registered protocol PROSPERO CRD420261360881): screening, data extraction, risk-of-bias assessment (AMSTAR-2/PROBAST/ROBINS-I), and GRADE certainty rating are conducted independently by at least two reviewers -- SPM (confirmed co-reviewer, registered in PROSPERO) as primary rater, with an external third reviewer to be identified and confirmed prior to peer-reviewed submission; JAD acts as guarantor and does not perform primary review tasks. All quantitative outputs reported here are preliminary estimates pending completion of the external third-reviewer audit; a triple-validated version will be posted as a subsequent preprint update before peer-reviewed submission. ResultsAdopted odds ratios: sleep disturbance 1.39 (95% CI 1.21-1.59; k=16; I{superscript 2}=51%), pain catastrophizing 2.10 (1.49-2.95; k=8; I{superscript 2}=0%), metabolic/obesity 1.43 (1.28-1.60; k=33), preoperative opioid exposure 5.32 (2.94-9.64; k=33; I{superscript 2}=99.96%; outcome: prolonged opioid use), and BZD co-prescription 1.77 (1.31-2.39; k=27; outcome: persistent opioid use). REML/Knapp-Hartung estimates produced wider confidence intervals for all loops (opioid: 1.87-15.13). PET-PEESE analysis suggested no substantial small-study effects for the sleep or catastrophizing loops. CCA=3.2% (slight overlap). Primary three-domain composite (sleep + catastrophizing + metabolic): delta method 95% confidence intervals for the composite score spanned 10-15 percentage points; PROBAST risk of bias: moderate. Secondary expanded six-domain composite (adding opioid, BZD, smoking): confidence intervals spanned 12-18 percentage points, crossing risk tier boundaries in moderate-risk patients; PROBAST risk of bias: high (driven by outcome heterogeneity in pharmacological domains). ConclusionsFive biopsychosocial risk factor domains are independently associated with chronic pain or related treatment outcomes. The PALF composite index is presented as a structured analytical framework for future prospective validation, not as a deployable clinical tool. The primary three-domain composite (sleep, catastrophizing, metabolic) achieves outcome homogeneity at the cost of reduced domain coverage; the expanded six-domain composite encompasses the pharmacological burden at the cost of outcome heterogeneity. Both composites carry wide confidence intervals that preclude clinical application without individual patient data validation. No claim to clinical validity is made in the absence of prospective individual-patient-data validation.

Background: Orthopedic surgeries are associated with significant intraoperative and postoperative pain, necessitating effective anesthesia strategies. Spinal anesthesia is commonly used for lower limb procedures due to its rapid onset and reliability; however, its limited duration may compromise prolonged surgical procedures and early postoperative pain control. Adjuvants such as dexamethasone have been explored to enhance and prolong the effects of local anesthetics. While evidence supports its efficacy, data from low-resource settings remain limited. Objective: To assess the effect of intrathecal dexamethasone as an adjuvant to bupivacaine on sensory block duration, time to first postoperative analgesia, and postoperative pain in patients undergoing lower limb orthopedic surgery at KCMC. Methodology: A randomized, double-blind controlled trial was conducted among 96 adult patients undergoing elective lower limb orthopedic surgery under spinal anesthesia. Participants were allocated using a computer-generated randomization sequence to receive either bupivacaine 15 mg with dexamethasone 4 mg (intervention group) or bupivacaine 15 mg with 1 ml normal saline (control group). Outcomes included sensory and motor block duration, time to first postoperative analgesia, and postoperative pain scores. Results: The dexamethasone group demonstrated a significantly prolonged sensory block duration (231 +/- 6 vs. 156 +/- 9 minutes; mean difference 75.11 minutes, 95% CI: 71.92-78.29; p < 0.001) and delayed time to first postoperative analgesia (252 +/- 7 vs. 181 +/- 7 minutes; mean difference 71.89 minutes, 95% CI: 68.91-74.86; p < 0.001). Motor block duration was also significantly longer (184 +/- 7 vs. 130 +/- 5 minutes; mean difference 53.42 minutes, 95% CI: 50.99-55.85; p < 0.001). Postoperative pain scores were significantly lower at 1 hour (mean difference -1.29 points, 95% CI: -1.52 to -1.05; p < 0.001) and at 2 hours (mean difference -1.97 points, 95% CI: -2.21 to -1.73; p < 0.001). Intraoperative opioid and benzodiazepine use were significantly reduced in the intervention group. Conclusion: The addition of intrathecal dexamethasone to bupivacaine significantly enhances sensory block duration, delays postoperative analgesia need, and improves early pain control. These findings support its use as a potentially practical adjuvant in resource-limited settings.

Background Observational studies have reported an association between inflammation and postoperative complications but it is unclear whether these associations are causal. It is also unknown whether postoperative outcomes share a causal architecture with chronic, all-cause disease. Methods We performed bi-directional two-sample Mendelian randomization to investigate potential causal effects of 19 genetically-proxied inflammatory markers on postoperative acute kidney injury, atrial fibrillation (AF), delirium, myocardial infarction, stroke and surgical site infection, and their all-cause equivalents. Genetic instruments for inflammatory markers were sourced from nine GWAS of up to 204,402 European participants with outcome data derived from UK Biobank. Results The primary postoperative analysis showed a protective effect of down-regulated IL-6 signalling on stroke risk (OR (95% CI) 0.27 (0.11--0.69), p=0.006). However, in the all-cause analysis a causal effect on stroke was not present (OR (95% CI) 1.14 (0.75--1.24), p=0.78), whilst a robust protective effect was seen for down-regulated IL-6 with AF across all three instruments studied (all p<0.009). In postoperative and all-cause analyses, genome-wide variants for CRP showed a protective effect on delirium that was not present in cis-restricted analyses. Conclusions We found evidence supporting a potential causal role for IL-6 signalling in perioperative stroke. However, the divergence in IL-6 effects between postoperative and all-cause outcomes suggests that the inflammatory architecture of acute postoperative complications may differ from chronic disease states. Furthermore, our findings suggest previously reported associations between CRP and delirium likely represent horizontal pleiotropy rather than direct causation. Future work should interrogate local tissue responses and the immediate perioperative period.

Objective: To quantify the effect size of four biopsychosocial amplifier loops on chronic pain outcomes through systematic review and meta-analysis, and to develop a logistic regression-based risk stratification tool for interventional pain medicine. Methods: We searched PubMed, Scopus, and Cochrane Library through March 2026 for studies reporting adjusted odds ratios for associations between (1) sleep disturbance, (2) pain catastrophizing, (3) metabolic/inflammatory markers, (4) preoperative opioid use/polypharmacy, and chronic pain chronification or treatment failure. Random-effects meta-analyses (DerSimonian-Laird) were performed for each loop. Effect sizes were translated into a composite logistic regression model, the Pain Amplifier Loop Framework (PALF), using ln(OR) as first-order coefficient approximations. Results: Forty-four studies with over 500,000 participants were included. Pooled odds ratios were: sleep disturbance OR=1.80 (95% CI 1.65-1.96; k=16), pain catastrophizing OR=2.11 (95% CI 1.71-2.61; k=8), metabolic/fat mass OR=2.02 (95% CI 1.32-3.09; k=7), preoperative opioid use OR=4.48 (95% CI 2.87-6.97; k=6), and opioid-benzodiazepine co-prescription OR=2.62 (95% CI 1.76-3.89; k=7). All four loops converge on TLR4/NF-kB microglial signaling. The PALF model produces a probability of interventional failure enabling stratification into low, moderate, and high risk categories. Conclusions: Four amplifier loops independently increase chronic pain risk. The PALF provides a transparent, clinically actionable risk score requiring prospective validation.

Amitriptyline is commonly prescribed for chronic pain, yet treatment response and tolerability vary substantially. Genetic variation in CYP2C19 and CYP2D6 influences amitriptyline metabolism, but evidence linking pharmacogene status to clinical outcomes in chronic pain is limited. Amitriptyline is typically prescribed for chronic pain at lower doses than for depression, which may reduce pharmacogenomic effects on clinical outcomes. We analysed 1,146 participants with chronic pain from the Australian Genetics of Depression Study who reported amitriptyline use, treatment outcomes, and genotype data. Metaboliser phenotypes were assigned using PharmCAT. Associations with self-reported effectiveness and discontinuation due to side effects were examined using regression models adjusted for age and sex. Only CYP2C19 intermediate metabolisers showed nominally lower odds of discontinuation and reduced likelihood of reporting moderate effectiveness. Overall, pharmacogenetic phenotypes were not significantly associated with patient-reported amitriptyline outcomes in chronic pain, potentially reflecting the lower doses typically prescribed for pain management.

Background: Post-operative hypotension and vasoplegia are well recognised following cardiac surgery but remain poorly characterised after major non-cardiac surgery, despite associations with acute kidney injury (AKI), cardiovascular complications, and increased mortality. Dysregulation of the renin angiotensin aldosterone system (RAAS) may underpin haemodynamic instability in this setting, yet data in abdominal surgery are limited. Objectives: The POLECAT (Perioperative delta Renin) study aims to determine whether changes in circulating renin concentration (delta renin) from pre-operative baseline to the early post-operative period are associated with post-operative vasoplegia in patients undergoing major abdominal surgery requiring intensive care admission. Methods: POLECAT is a single-centre, prospective observational study conducted at a UK tertiary referral hospital. Adult patients undergoing planned or emergency abdominopelvic surgery with anticipated intensive care admission are enrolled. Blood samples are obtained pre-operatively, within four hours post-operatively, and on post-operative day one to measure renin and a panel of endothelial, renal, and immune biomarkers. The primary outcome is post-operative vasoplegia, defined as the requirement for a vasopressor infusion at 08:00 on post-operative day one. Secondary outcomes include alternative vasoplegia definitions, AKI (KDIGO criteria), vasopressor burden, organ dysfunction, cardiovascular complications, length of stay, and mortality. Multivariable regression, receiver operating characteristic analyses, and predefined subgroup analyses will be performed, with sensitivity analyses addressing missing data. Conclusions: This study will clarify the relationship between peri-operative RAAS dysfunction and vasoplegia following major abdominal surgery. Findings may support biomarker-guided risk stratification and inform future interventional trials targeting haemodynamic instability in this high-risk population.

Background Complicated appendicitis (CA) increases morbidity and resource use.[1,2] In the emergency setting, risk stratification must rely on rapidly available data. Procalcitonin (PCT) is frequently obtained, but its incremental value beyond basic preoperative indicators remains uncertain.[5] We aimed to quantify PCTs incremental predictive value and develop a practical bedside score with temporal validation. Methods We conducted a retrospective cohort study of consecutive laparoscopic appendectomy patients (January 2023-December 2024). CA was defined by postoperative pathology (gangrene/necrosis, perforation, or peri-appendiceal inflammation/abscess; worst-category rule). We compared a base logistic model (age, WBC, neutrophil percentage, fever, symptom-to-surgery interval, shock index) with an extended model adding log-transformed PCT. Discrimination (AUC) and calibration were assessed. Temporal validation used 2023 for development and 2024 for testing. We also created a simple bedside score using pre-specified cutoffs and evaluated CA risk across score strata in 2024. Results In the overall complete-case cohort (n=1,792), 397 patients (22.2%) had CA. Adding PCT modestly improved discrimination in the full cohort (AUC 0.673 to 0.685). For temporal validation, 2023 included 870 patients (CA 26.9%) and 2024 included 921 patients (CA 17.7%); one otherwise eligible patient lacked a usable admission year. In the 2024 test set, discrimination was 0.662 (base) vs 0.673 (base+PCT) with a non-significant AUC difference (DeLong p=0.116); calibration slopes were near 1.0. A 7-item bedside score stratified 2024 CA risk: 9.1% (score 0-1), 14.7% (2-3), and 34.2% [&ge;]4). Using [&ge;]4 points identified a higher-risk subgroup (PPV 34.2%, NPV 87.5%, sensitivity 46.0%, specificity 81.0%). Conclusions PCT adds modest predictive information beyond simple preoperative indicators in the full cohort, but temporal validation suggests that this incremental gain is smaller and not statistically significant in later patients. A pragmatic bedside score can support CA risk stratification and prioritization in emergency care, whereas the role of routine PCT testing may be best reserved for selected situations in which uncertainty remains after initial assessment.

Objective: To quantify the effect size of four biopsychosocial amplifier loops on chronic pain outcomes through systematic review and meta-analysis, and to propose a composite meta-analytic risk index for interventional pain medicine requiring prospective validation. Methods: We searched PubMed/MEDLINE, Scopus, and the Cochrane Library through March 2026 for studies reporting adjusted odds ratios linking (1) sleep disturbance, (2) pain catastrophizing, (3) metabolic/inflammatory markers, and (4) preoperative opioid use/polypharmacy to chronic pain chronification or treatment failure. DerSimonian-Laird random-effects meta-analyses were performed per loop. Publication bias was assessed via Egger's test (k>=8). Effect sizes were integrated into a logistic regression model--the Pain Amplifier Loop Framework (PALF). Neurobiological convergence on TLR4/NF-kB microglial signaling was examined. Results: Forty-four studies (>500,000 participants) were included. Pooled odds ratios: sleep disturbance 1.80 (95% CI 1.65-1.96; k=16; I2=51%), pain catastrophizing 2.11 (1.71-2.61; k=8; I2=0%), metabolic/fat mass 2.02 (1.32-3.09; k=7), preoperative opioid use 4.48 (2.87-6.97; k=6; I2=84%), and opioid-benzodiazepine co-prescription 2.62 (1.76-3.89; k=7; I2=79%). Egger's test showed no significant asymmetry for sleep (p=0.21) or catastrophizing (p=0.84). All loops converge on TLR4/NF-kB microglial signaling. The PALF yields a Systemic Load Score and failure probability P=1/(1+e^-theta), enabling low (<0.30), moderate (0.30-0.60), and high (>=0.60) risk stratification. Conclusions: Four biopsychosocial amplifier loops independently and substantially increase chronic pain risk. The PALF proposes a transparent, hypothesis-driven composite risk index anchored in meta-analytic evidence from >500,000 participants. As a meta-analytic synthesis rather than a fitted prediction model, the PALF requires prospective multicenter validation with individual patient data before clinical application.

BackgroundVenous thromboembolism (VTE) remains a major cause of perioperative morbidity in cranial neurosurgery, yet clinical practice varies widely, and formal guidelines are inconsistent. Understanding internationally sampled neurosurgical practice is essential for informing consensus and future trials. MethodsAn international, 2-stage cross-sectional, internet-based survey was conducted. Practising neurosurgeons performing elective adult cranial surgery were eligible. Descriptive statistics were used to summarise practice. Responses covered patterns of pre-operative haemostasis decision making, use and timing of mechanical and/or chemical prophylaxis, use of perioperative imaging prior to anticoagulation, and frequency of clinical assessment for VTE. Associations with geographical income status, subspecialty, and years post-certification were statistically tested. Practice heterogeneity was quantified and contextual influence was summarised using mean effect sizes across stratifying variables in order to determine domains of true equipoise. ResultsOf 585 responses, 456 (78%) met criteria for inclusion: representing 322 units across 78 countries (71% high-income). Thirteen per cent reported no departmental VTE plan; 23% followed no guidelines and 12% used multiple. Routine pre-operative testing almost universally included haemoglobin/platelets/haematocrit, with fibrinogen more common in high-income settings. Compared with high-income country respondents, low- and middle-income respondents reported higher haemoglobin transfusion thresholds (>90 g/dL; p<0.001) and shorter antiplatelet interruption (p[&le;]0.03), and less frequent outpatient VTE assessment (p<0.001). Mechanical prophylaxis was common (TEDs 81%, IPC 62%), typically started pre-or intra-operatively. Among those completing the chemoprophylaxis section (n=310), 57% required a CT or MRI scan before LMWH which was then initiated on average 31.4 hours after surgery. 1% of respondents did not routinely use LMWH. Many clinical decisions demonstrated statistical equipoise ie. high heterogeneity with low contextual influence. ConclusionPeri-operative haemostasis and VTE prophylaxis practices in adult elective cranial neurosurgery vary substantially worldwide, with some decisions reflecting geographical or socioeconomic differences and many others reflecting true clinical equipoise rather than contextual determinants. By mapping contemporary real-world practice across diverse health-system contexts, this study provides a necessary empirical foundation for rational trial design and future guideline development.