Risk Factors and Clinical Presentations of Long COVID: A Retrospective Observational Propensity Score Matching Study

IntroductionLong COVID symptoms can affect multiple body systems and result in complicated clinical presentations. Research on long COVID is fraught with various challenges, particularly identifying risk factors, understanding pathophysiology, and implementing effective management strategies. This study assessed long COVID risk factors and evaluated the symptoms presented by affected individuals. MethodsWe conducted a hospital-based single-centre retrospective study of 627 adult patients managed for COVID-19. The patients were divided into long COVID and non-long COVID cohorts. We employed propensity score matching (PSM) to create matched groups of participants based on their predicted risk of long COVID and subsequently calculated the multiplicative effects on the odds of developing it. The prevalence of each clinical symptom was calculated as a percentage to determine the most common. ResultsThe study included 627 COVID-19 patients, with an average age of 59 ({+/-}20) years. The cohort included 375 without and 252 with long COVID. Each additional year of age increased the odds of long COVID by 6.4% (OR 1.06, p=0.00). BMI (OR 1.03, p=0.04), Asian or Asian British (OR 2.64, p = 0.03), and former smokers (OR 6.44, p=0.05) had significantly higher odds of long COVID. Long COVID risk rose with the number of comorbidities. Interstitial lung diseases (ILDs) (OR 2.93, p=0.02), high Clauss fibrinogen level (OR 1.22, p=0.00), and serum Sodium (Na+) (OR 1.07, p = 0.02) significantly increased the odds of long COVID. The most prevalent clinical presentations were fatigue (81%), shortness of breath (61%) and dry cough (19%). ConclusionsThe study identified key risk factors for long COVID, including age, BMI, ethnicity, former smoking habits, comorbidities, and ILDs. Clauss fibrinogen and serum Na+ were also significant biomarkers. The main symptoms were fatigue, shortness of breath, and dry cough. The multifaceted effects of long COVID necessitate a multidisciplinary approach to patient care. Key Messages What is already known on this topicO_LIAdvanced age, BMI, a history of severe COVID-19 infection, existing comorbidities, and chronic conditions such as diabetes mellitus (DM) were identified as risk factors for long COVID, and the symptoms frequently reported include fatigue, dyspnoea, cough, muscle and joint pain, cognitive deficits, and respiratory problems. C_LI What this study addsO_LIEthnic minorities (Asian or Asian British), ILDs, elevated levels of Clauss fibrinogen and serum Na+ increased the odds of developing long COVID. C_LI How this study might affect research, practice, or policyO_LIThe observed association between elevated Clauss fibrinogen levels and serum Na+ and long COVID necessitates in-depth research into the role of fibrinogen and deranged electrolytes in the pathophysiological processes of long COVID. Elucidating these mechanisms could facilitate the development of predictive models and targeted therapeutic interventions. C_LI