Impact of Comorbidities on Lassa Fever Outcomes: A 7-Year Retrospective Analysis of Cases Managed at Infection Control and Research Centre FMC Owo

Abstract

Background: Lassa fever (LF) remains a major public health challenge in West Africa, particularly Nigeria, where recurrent outbreaks contribute substantially to morbidity and mortality. Although most infections are mild or asymptomatic, severe disease may involve multi-organ dysfunction and poor outcomes. The influence of underlying comorbidities on disease severity remains inadequately characterised, despite its relevance to clinical management and risk stratification. Objective: To determine the prevalence of comorbidities and assess their effect on Lassa fever severity and clinical outcomes among patients managed at a tertiary isolation centre in Nigeria. Methods: This retrospective analytical study reviewed medical records of confirmed Lassa fever cases managed at the Infection Control and Research Centre, Federal Medical Centre, Owo, from 2018 to 2024. A total of 131 patients with documented comorbidities were included. Socio-demographic characteristics, comorbid conditions, and clinical outcomes were extracted using a structured checklist. Data were analysed using SPSS version 27. Descriptive statistics summarised patient characteristics, while chi-square and likelihood ratio tests assessed associations. Multivariable logistic regression identified independent predictors of disease severity, with statistical significance set at p < 0.05. Results: Of 1,682 cases reviewed, 131 (7.79%) patients with Lassa fever and comorbidities were included. The mean age was 50.01 ± 15.63 years, and 58.8% were female. Hypertension (48.7%), peptic ulcer disease (24.7%), and diabetes mellitus (20.3%) were the most common comorbidities. Age was significantly associated with hypertension (p < 0.001), diabetes mellitus (p = 0.010), and peptic ulcer disease (p = 0.001), with the highest burden among individuals aged 40–59 years. Only peptic ulcer disease (PUD) was significantly associated with Lassa fever severity (p = 0.008). Multivariable analysis identified PUD as an independent predictor of severe disease (adjusted odds ratio [AOR] = 2.901; 95% CI: 1.292–6.513; p = 0.010), indicating an almost threefold increase in complication risk. Conclusion: Comorbidities were common among patients with Lassa fever. Hypertension, PUD, and diabetes mellitus were most frequently documented. PUD independently predicted severe disease, supporting targeted monitoring, early intervention, and routine comorbidity screening to strengthen risk-based clinical management.