Comparison of methods for assessing Chlamydia trachomatis transmission intensity: a systematic review

Structured AbstractO_ST_ABSTopicC_ST_ABSTo assess the relationship between field-graded trachomatous inflammation--follicular (TF) and other methodologies for evaluating Chlamydia trachomatis (Ct) transmission intensity. Clinical relevanceTF has limitations as the sole indicator of Ct transmission for trachoma programmatic decision-making. The relationships between TF and other indicators, including other clinical signs, photography, infection, and serology have yet to be synthesized. MethodsA systematic review was conducted. Five databases (MEDLINE, EMBASE, Global Health database, Scopus, and Global Index Medicus) were searched on October 19, 2022, and the e-Theses Online Service was searched on April 12, 2023. Studies from 1987 onward that reported primary data collection of field-graded TF in children and at least one other indicator were included. To compare field-graded vs. photo-graded TF, the mean difference in prevalence and 95% confidence intervals (CIs) were calculated. To compare field-graded TF against the other indicators, weighted correlation coefficients and p-values were calculated in pre-vs. post-antibiotic mass drug administration (MDA) settings. The review protocol was prospectively registered with PROSPERO (CRD42022356013). ResultsA total of 35,764 studies were screened, yielding 235 included studies from 49 countries, spanning the years (of data collection) 1991-2021. For field-graded vs. photo-graded TF (n=10), the mean difference in prevalence was 0.7 percentage points, 95% CI (-15.2-16.7). The relationship between TF and other indicators was stronger pre-vs. post-MDA: TF vs infection (R2: 0.43, p=0.003 vs. R2: 0.002, p=0.788); TF vs seroprevalence (R2: 0.56, p<0.001 vs. R2: 0.03, p=0.353); and TF vs seroconversion rate (SCR) (R2: 0.52, p=0.012 vs. R2: 0.26, p=0.061). Post-MDA, infection and SCR were highly correlated (R2: 0.71, p=0.001). In studies reporting data used for programmatic decision-making, 48% of the areas warranting MDA based solely on TF had at least one other indicator categorized as indicating "low" or "medium" Ct transmission intensity. ConclusionsThe correlation between TF and measures of infection and serology weakens post-initiation of MDA, which is strongly suggestive of poor performance of TF prevalence for guiding programmatic decision-making post-MDA. Measures of infection and SCR are strongly correlated with each other post-MDA. Infection and/or serology should be considered to help guide programmatic decision-making post-MDA. Target JournalOphthalmology