[Investigation of temporal and spatial characteristics of allergic rhinitis epidemics by Baidu Index in China]

Objective: To explore the temporal and spatial characteristics of search volume (SV) of allergic rhinitis (AR) and related search terms on Baidu Index, as well as the correlation between SV from Baidu Index and epidemiology of AR. Methods: SV of AR and related search terms in mainland area of China from January 2012 to December 2016 were extracted from Baidu Index. Firstly, we investigated the temporal and spatial characteristics of SV of AR and related search terms ("pollen allergy" and" dust mite allergy", etc.), and explored the correlation between SV of AR and SV of related search terms. Secondly, the SV of specific search terms in Beijing and Guangzhou were compared with the actual pollen count in Beijing from April to September in 2016 and the monthly outpatient volume of AR patients in the Otorhinolaryngology Hospital, The First Affiliated Hospital of Sun Yat-sen University from 2014 to 2016 respectively to analyze the consistency between SV from Baidu Index and the real-world data. Spearman correlation analysis was used to explore the correlation between different search terms according to the normality and homogeneity of variance of the data. P<0.05 was considered statistically significant. Results: SV of AR showed repetitively seasonal pattern, with the first peak in May and the second peak from August to September. SV of AR in northeast China, north China and northwest China were correlated with both SV of "pollen allergy" and "dust mite allergy" (r value was 0.533, 0.638, 0.609, 0.791, 0.517, 0.682, respectively, all P<0.05). In east China, central China, south China and southwest China, SV of AR showed significant correlation only with SV of "dust mite allergy" (r value was 0.897, 0.884, 0.799, 0.937, respectively, all P<0.05), but not with SV of "pollen allergy" (r value was 0.110, 0.171, 0.020, 0.265, respectively, all P>0.05). The correlation between pollen count and the SV of AR on the day and SV of "pollen allergy" on the next day was the highest (r value was 0.692 and 0.713, respectively, all P<0.05). The SV of AR was correlated with the monthly outpatient volume of AR patients one month and two months later (r value was 0.523 and 0.503, respectively, all P<0.05). Conclusion: The SV of AR and related search terms show different trends in different times and regions which are consistent with the AR epidemiological survey, and significantly correlate with pollen count and AR outpatient volume.