Incidence of acute diarrheal illness in Chinese communities: a meta-analysis

Background: Acute diarrheal illness (ADI) is an important public health problem worldwide. We estimated the morbidity, distribution, and burden of self-reported ADI in China over the last three decades. Methods: We used the keywords "diarrhea and morbidity" to identify studies published in Chinese by searching CNKI, WANFANG, Chongqing VIP, and SinoMed. Studies published in English were identified using the keywords "diarrhea, morbidity, and China" to search Pubmed/Medline, Embase, and Cochrane Library Data. All articles published before Dec 31, 2014 were included in the search. Data were extracted and the pooled 2-week incidence rate of ADI was calculated using the fixed-effects or random-effects model according to statistical testing for homogeneity. The incidences of each subgroup (organized by age, location, study period) were also calculated. Publication bias was examined using Begg's test. Data manipulation and statistical analyses were undertaken using R-2.15.1 software. Results: We estimated that the pooled 2-week prevalence of ADI in China was 2.04% (95% CI: 1.48-2.79) and that the corresponding incidence rate was 0.53 (95% CI: 0.38-0.73) episodes per person-year. The ADI rate was highest among children aged < 5 years (1.43 episodes per person-year), and it was slightly higher in males than in females (0.58 vs 0.52 episodes per person-year). From 1980 to 2012, there was a significant decrease in the incidence of ADI, from 0.82 to 0.48 episodes per person-year, but the ADI incidence was consistent over the last two decades. Additionally, the incidence of ADI was higher in rural areas and in west China and peaked in the summer months. Conclusions: The current study indicates that ADI caused a substantial disease burden in China in the last 30 years, especially in rural areas and west China, where sanitation conditions were relatively poor. These findings highlight the importance of further investigation of the specific causes of and effective preventive measures for ADI.