Assessment of temperature effect on childhood hand, foot and mouth disease incidence (0-years) and associated effect modifiers: A 17 cities study in Shandong Province, China, 2007-2012

Background: Previous studies examining temperature-disease associations of hand, foot and mouth disease (HFMD) mainly focused on a single city. The results demonstrated great heterogeneity. A multi-city study is necessary to better understand temperature risk on the childhood incidence of HFMD and the associated modified factors. Objective: To assess the effect of ambient temperature on childhood HFMD incidence and explore the potential associated effect modifiers in the study area. Methods: Daily morbidity data and meteorological variables of the 17 cities were collected for the period from 2007 to 2012. Distributed lag non-linear model (DLNM) was used to estimate city-specific effects of temperature on HFMD incidence. A multivariate meta-analysis was then applied to pool the estimated city-specific effect. Potential effect modifiers were included in the multivariate meta-regression as meta-predictors. Results: A total of 504,017 childhood HFMD cases were included in the study. The high-incidence period of HFMD was detected in late spring and early summer (April to June). The temperature-disease associations of the 17 cities demonstrated great heterogeneity and the pooled exposure-response curve was an approximately inverted V-shape. Regional indicator, numbers of healthcare institution and annual household income were considered as associated modifiers. Conclusion: Our findings can provide a practical reference for the early warning and intervention strategies of HFMD. Different temperature-disease associations among different regions should be considered when formulating and optimizing public health policy.