[Epidemiological characteristics and risk factors of primary intussusception in children among two years old and below, Ji'nan city].

Objective: To study the epidemiological characters and risk factors of primary intussusception among children who were ≤2 years old in Jinan city. Methods: A retrospective study was also applied to collect the disease information of inpatient cases through hospital information system of inpatient during 2011 and 2015. The attack rate (AR) was calculated in total and each year, respectively. 1∶(1) matched pared case-control study was conducted to explore the risk factors of primary intussusception. A total of new confirmed 93 residential cases were enrolled with ≤2 years old, diagnosed as primary intussusception or diseases coded as K56.1 according to the International Classification of Diseases, tenth version (ICD-10), and without any other reason for organic lesions. The 93 patients without primary intussusception inpatients were selected from the same hospital and departments as the controls, and matched with the cases as the same gender, ±3 months old, and disease onset within 7 days, visiting the hospital during January 1, 2016 and June 30, 2016. Clinical and epidemiological information was collected both from cases and controls. The difference of AR among different years was compared by Trend Chi-squiare test, and difference between gender, month old and regions was compared by Chi-squiare test, respectively. Multiple-variables factor analysis was applied to analysis the risk factors of cases compared with controls by conditional logistic regression model. Results: A total of 574 cases were found and the overall AR was 86.3 per 100 000. A significant decreasing trend (χ(2trend)=23.43, P< 0.001) of AR was showed between 2011 and 2015, with the highest AR in 2011 (117.6 per 100 000), and the lower AR in 2014 (66.0 per 100 000). The lowest AR was also observed in male (106.9 per 100 000) compared with the female (63.2 per 100 000) (χ(2)=13.76, P< 0.001), and in ≤12 months old (102.1 per 100 000) compared with the >12 months old (70.4 per 100 000) (χ(2)=19.46, P< 0.001). The higher proportion of 57.1% (328/574) was found in 4-12 months old cases. The cases with an overweight before illness ( OR= 4.98, 95 %CI: 1.27-19.50), with mixed feeding of breast-milk and milk-powder ( OR= 16.90, 95 %CI: 5.25-54.20), and with instruction of solid food before 6 months old ( OR= 16.50, 95 %CI: 1.91-143.10) could increase the risk of illness compared with keeping a healthy weight, breast feeding, and instruction of solid food after 6 months old, separately. Conclusion: A higher attack rate of primary intussusception in children with a ≤2 years old in Jinan was observed. Male and 4-12 months group had a higher risk. Body weight, breast feeding, and the instruction of solid food before and after 6 months old were related to the risk of primary intussusception among children who were ≤2 years old.