Clinical Outcomes of Severe Lassa Fever in West Africa: A Systematic Review and Meta-Analysis

Abstract

Lassa fever (LF) is an acute viral hemorrhagic fever that poses a substantial public health security threat in West Africa. The non-specific clinical presentation of LF, coupled with a lack of reliable point-of-care diagnostics, means delayed diagnosis, leading to severe complications and mortality during epidemics. A systematic review and meta-analyses were performed by conducting an extensive online search using PubMed, Web of Science, Scopus, CINAHL, and Google Scholar (PROSPERO protocol identifier number CRD42024587426). Only peer-reviewed studies written in English were included in publications from 1 September 2014, to 31 August 2024. The analysis and reporting followed PRISMA guidelines. The quality of the included studies was assessed using the critical appraisal tools developed from the Joanna Briggs Institute Systematic Review Checklist for cohort studies. We included 19 studies that contained data from 4177 patients hospitalized with LF of any age. Most included studies employed a retrospective cohort design and were conducted in Nigeria (16/19; 84.2%). The mortality rate was highest in a Sierra Leonean study (63.0%), whereas a group-based analysis of Nigerian studies using a random-effects model identified Owo as having the highest mortality rate of 13% (95% CI: 6-23; I² = 98%). The pooled mortality rate for severe LF was 19% (95% confidence interval [CI]:10-32). The most common complications of LF are acute kidney injury (AKI) at a pooled proportion of 19% (95% CI; 13-26; I² = 89%)), followed by abnormal bleeding at a pooled proportion of 17% (95% CI; 9-30; I² = 98%), and central nervous system (CNS) dysfunction at a pooled proportion of 15% (95% CI; 6-32; I2 = 98%). With one out of every five hospitalized LF patients likely to die in West Africa, accelerating the development of rapid diagnostic tests, licensed vaccines, and novel therapeutics is crucial. Strengthening community engagement and risk communication, developing regional treatment guidelines, decentralizing LF care units, and training healthcare workers using a harmonized curriculum will enhance early diagnosis and effective case management, thereby reducing severe complications and mortality.

Keywords: CNS dysfunction; Lassa fever; West Africa; abnormal bleeding; acute kidney injury; mortality rate.

Figure 1

PRISMA flow chart.

Figure 2

Percentage of studies analyzed by country.

Figure 3

Percentage of included studies based on year of publication.

Figure 4

Frequency of complications of severe LF.

Figure 5

Pooled proportions of death and recovery as outcomes of severe LF. [17,18,19,20,22,23,24,25,26,27,28,29,30,31,32,33,34,35].

Figure 6

Subgroup results of death and recovery outcomes by year of publication. [17,18,19,20,22,23,24,25,26,27,28,29,30,31,32,33,34,35].

Figure 6

Subgroup results of death and recovery outcomes by year of publication. [17,18,19,20,22,23,24,25,26,27,28,29,30,31,32,33,34,35].

Figure 7

Subgroup analysis of mortality and survival outcomes by locations in Nigeria. [17,18,19,20,22,23,24,27,28,32,33,34,35].

Figure 7

Subgroup analysis of mortality and survival outcomes by locations in Nigeria. [17,18,19,20,22,23,24,27,28,32,33,34,35].

Figure 8

Pooled proportions of abnormal bleeding as outcomes of severe LF. [17,18,20,21,23,24,27,28,32,33].

Figure 9

Subgroup analysis of abnormal bleeding by locations in Nigeria. [17,18,20,21,23,24,27,28,32,33].

Figure 10

Pooled proportions of acute kidney injury as a clinical outcome of severe LF. [17,18,20,21,23,27,33].

Figure 11

Pooled proportions of CNS dysfunction as a clinical outcome of severe LF. [20,23,28,32,33].

Figure 12

Funnel plot of death as a clinical outcome of severe LF. The study effect size spread (shown by gray dots) indicates low publication bias and study heterogeneity.

Figure 13

Funnel plot of recovery as a clinical outcome of severe LF. The higher spread of dots in the upper half indicates study heterogeneity and predominance of larger studies.

Figure 14

Funnel plot of CNS dysfunction as a clinical outcome of severe LF. Few studies (gray dots) indicate limited evidence, and the studies (gray dots) suggest a high likelihood of publication bias.

Figure 15

Funnel plot of AKI as a clinical outcome of severe LF. Few studies (gray dots) indicate the limitation of evidence and low asymmetry.

Figure 16

Funnel plot of abnormal bleeding as a clinical outcome of severe LF. The few with effect sizes showing slight asymmetry suggest a potential publication bias.