Y Lou, SJ Huang, JF Tou, ZG Gao, JF Liang

Abstract

Purpose: This study aimed to reveal the effect of ambient temperature on the occurrence of acute appendicitis (AA) in children under 5 years of age. Methods: We identified 4159 patients with AA from January 2003 to November 2012. Totally 1071 patients were under 5 years (younger patients), and 3088 aged 6-14 years (older patients). Pearson's correlation analysis was used to examine the correlation between ambient temperature and the occurrence of AA. We used Auto-Regressive Integrated Moving Average (ARIMA) models to examine the effects of climatic factors on incidence rates. Results: Pearson's correlation analysis showed a correlation between monthly incidence and monthly average temperature for entire sample (r=0.404, p<0.001), for younger patients (r=0.209, p=0.023), and for older patients (r=0.421, p<0.001). The correlation was lower than that between daily average cases of each temperature (DACET) and 1- to 12-day average temperature for entire sample (0.80±0.04, all p<0.01), for younger patients (r=0.52±0.09, all p<0.05), and for older patients (r=0.79±0.04, all p<0.01). According to age, younger patients had a much lower r value than older patients (p<0.001). The peak r value of the correlation between DACET and n-day average temperature indicated that n was 6 for entire sample, 3 for younger patients and 7 for older patients. A 1°C increase in 6-day average temperature was associated with an increase of 0.0202, 0.0044 and 0.0157 in daily average cases for entire sample (r²=0.78, p<0.001), younger patients (r²=0.29, p=0.004), and older patients (r²=0.68, p<0.001), respectively. ARIMA models revealed that monthly incidence rate was associated with ambient temperature for both younger patients and older patients (both p<0.01). Conclusion: More AA occurred under higher ambient temperature. As compared with the older patients, ambient temperature had a weaker but quicker effect on the occurrence of AA in children under 5 years of age.