The healthcare seeking rate of individuals with influenza like illness: a meta-analysis

Background: Not all individuals with Influenza like illness (ILI) seek healthcare. Knowing the proportion that do is important to evaluate the actual burden and fatality rate of ILI-relevant diseases, such as seasonal influenza and human infection with avian influenza. A number of studies have investigated the healthcare seeking rate, but the results varied from 0.16 to 0.85. We conducted this analysis for better understanding the healthcare seeking rate for ILI, and providing fundamental data for researchers in relevant fields. Methods: In this meta-analysis, a total of 799 articles, published as of 13 December 2016, were retrieved from Pubmed, Embase, Web of Science and Cochrane, and 11 of them were included after screening. The pooled estimates and factors which influence healthcare seeking rates were analysed. Results: The overall pooled healthcare seeking rate was 0.52 (95% CI: 0.46-0.59). The rate was significantly higher during the H1N1 pandemic in 2009 (0.61, 95% CI: 0.51-0.74), in children (0.56, 95% CI: 0.55-0.57) and in patients with documented fever (0.62, 95% CI: 0.53-0.72) than during non-pandemic periods (0.39, 95% CI: 0.33-0.45), in adults (0.45, 95% CI: 0.42-0.48) and in patients without documented fever (0.44, 95% CI: 0.38-0.50). Meta-regression indicated that these three factors could jointly explain 70.1% of the total heterogeneity among published studies. Conclusion: The healthcare seeking rate of ILI patients is needed for estimation of the burden of ILI in the general population based on data from routine ILI sentinel surveillance systems.