[Effect of daily average temperature on the incidence of allergic rhinitis in Lanzhou]

Objective: To evaluate the effect of daily average temperature on the atteck of allergic rhinitis (AR) by analyzing the changes of the outpatient visits of AR in Lanzhou. Methods: The meteorological and air pollution data of Lanzhou City and the outpatient visits of AR in Departments of Otorhinolaryngology and head and neck surgery of The First Hospital of Lanzhou University, The Second Hospital of Lanzhou University and Gansu Provincial People's Hospital from 2013 to 2017 were collected to describe the meteorological factors, air pollutants and the outpatient visits of AR. The correlation among the three factors was then analyzed by Spearman rank correlation analysis. Using the distributed lag non-linear model, the relationship between daily average temperature and the number of daily outpatient visits of AR was studied and stratified by gender and age with the long-term trend, seasonal trend and other confounding factors controlled. Results: From 2013 to 2017, the outpatient visits of AR in the above three hospitals reached 20 008 person times. Daily average temperature in Lanzhou showed a non-linear correlation to the outpatient visits of AR, with a certain lag effect. When the daily average temperature was 22 ℃ and the cumulative lag was 21 days (lag 0-21 d), the relative risk (RR) peaked at 4.851 (95%CI: 3.986-5.904). The effect of relatively low temperature (2.3 ℃, P₂₅), relatively high temperature (19.8 ℃, P₇₅) and high temperature (25.5 ℃, P₉₅) on lag 0-21 d were the highest, which were 1.761 (95%CI: 1.375-2.255), 4.299 (95%CI: 3.574-5.171) and 3.656 (95%CI: 3.046-4.389), respectively. According to the stratified analysis, low and relatively low temperature had more significant effect on the outpatient visits of AR among women and people aged 0-14 years. When lag was 0-21 days, the RR value of low temperature for female outpatient visits of AR was 1.433 (95%CI: 1.105-1.860); the RR value of relatively low temperature for female outpatient visits of AR was 1.879 (95%CI: 1.460-2.419); the RR value of low temperature for AR outpatient visits for people aged 0-14 years was 1.511 (95%CI: 0.999-2.287), the RR value of relatively low temperature for AR outpatient visits for people aged 0-14 years was 2.051 (95%CI: 1.383-3.042). Relatively high temperature, on the other hand, had a more significant effect on men and people aged 15-59 years. High temperature had a greater impact on the number of AR outpatients in men and people aged 0-14 years. Conclusions: Temperature may be an important influencing factor of AR onset in Lanzhou. At relatively high temperature (19.8 ℃), the risk of AR outpatient visits is significantly increased, and the cumulative lagged effects are observed. The sensitivity of AR patients to temperature is different in different genders and ages.