[Influence of diurnal temperature range on influenza incidence in the elderly]

Objective: To understand the influence of diurnal temperature range (DTR) on influenza incidence in the elderly in Beijing and to conduct a subgroup analysis. Methods: The incidence data of daily influenza cases in the elderly and daily meteorological data from 2014 to 2016 in Beijing were collected for this study. A generalized additive model (GAM) was used to explore whether the relationship between daily influenza cases and DTR is a linear one. A distributed lag non-linear model (DLNM) was established to quantify the lagged effect of DTR on daily influenza incidence in the elderly. The model was also used to estimate the effects of DTR on daily influenza incidence among various subgroups. Results: A total of 4 097 influenza cases in the elderly were notified during study period. The mean DTR was 10.153 ℃. A linear relationship between daily influenza incidence and DTR was detected by using GAM. DTR was significantly associated with daily influenza incidence between lag0 and lag5 with a maximal effect at lag0. An 1 ℃ increase of DTR was associated with a 2.0% increase in daily influenza incidence in the elderly (95%CI: 0.9%-3.0%). The RR values of males, females, people aged 60-69 years, people aged ≥70 years were 1.018 (95%CI: 1.005-1.032), 1.021(95%CI: 1.007-1.035), 1.012 (95%CI: 1.002-1.022), 1.025 (95%CI: 1.012-1.039), respectively. The influencing time of DTR on females (lag6) was longer than males (lag2). Conclusions: DTR was associated with increased risk of influenza in the elderly in Beijing. It is necessary to take targeted measures in the elderly to control the incidence of influenza when DTR becomes greater.