Fatigue outcomes following an influenza virus pandemic: A systematic review and meta-analysis

Poole-Wright, K. F.; Gaughran, F.; Evans, R.; Chalder, T.

Objectives: Fatigue is a pervasive clinical symptom for many infected with an influenza virus. Prior evidence from influenza pandemics suggest that fatigue symptomology may continue beyond the acute phase, lasting for several months to several years post discharge. This living systematic review aimed to examine long term fatigue prevalence among survivors and among communities, as well as investigate the current evidence for associated factors. Design:Systematic review and meta-analysis. Setting: Hospitalised and community samples. Participants:Patient populations with a confirmed diagnosis of a named influenza virus. Main outcomes measured: Fatigue, fatigue syndromes. Results: Ten studies met the inclusion criteria for a pooled prevalence analysis and five studies were identified as eligible for a means differences analysis. A fatigue prevalence of 41% (95% CI 0.2990.488) was found among a total population of 1,310. Using the vitality sub-scale of the SF-36 as a proxy for fatigue, the estimate for means differences indicated a lower mean vitality score for survivors compared to population norms (M -1.523, CI -13.53-10.48), although this was not significant (P = 0.803). The most common associations with fatigue were PTSD, depression and anxiety, ICU admission, female gender and higher age. Conclusions: This study reveals that a significant proportion of survivors (41%) experienced fatigue following their recovery from an influenza virus such as SARS or MERS and that this fatigue can be long-lasting. Also, that some factors such as female gender and psychological factors may contribute to continuing fatigue outcomes for this population. Strengths and limitations: (a) this study provides support for long-term fatigue outcomes in people with a confirmed coronavirus or other influenza virus pandemic, (b) the study suggests an aetiological role for some psychological and social factors, (c) findings are limited by the availability of fatigue data and lack of pre-morbid fatigue information; (d) a meta-analysis on the associations was prohibited by the small number of studies investigating long-term fatigue correlates and (e) the heterogeneity of the studies (>75%) suggests the pooled estimates should be interpreted with caution.