A multi-country study of intussusception in children under 2 years of age in Latin America: analysis of prospective surveillance data

Abstract

Background: Intussusception (IS) is a form of acute intestinal obstruction that occurs mainly in infants and is usually of unknown cause. An association between IS and the first licensed rotavirus vaccine, a reassortant-tetravalent, rhesus-based rotavirus vaccine (RRV-TV), led to the withdrawal of the vaccine. New rotavirus vaccines have now been developed and extensively studied for their potential association with IS. This study aimed to describe the epidemiology and to estimate the incidence of IS in Latin American infants prior to new vaccine introduction.

Methods: Children under 2 years of age representing potential IS cases were enrolled in 16 centers in 11 Latin American countries from January 2003 to May 2005. IS cases were classified as definite, probable, possible or suspected as stated on the Brighton Collaboration Working Group guidelines.

Results: From 517 potential cases identified, 476 (92%) cases were classified as definite, 21 probable, 10 possible and 10 suspected for intussusception. Among the 476 definite IS cases, the median age at presentation was 6.4 months with 89% of cases aged <1 year. The male to female ratio was 1.5:1. The incidence of definite IS per 100,000 subject-years ranged from 1.9 in Brazil to 62.4 in Argentina for children <2 years of age, and from 3.8 in Brazil to 105.3 in Argentina for children aged <1 year. Median hospital stay was 4 days with a high prevalence of surgery as the primary treatment (65%). Most cases (88%) made a complete recovery, but 13 (3%) died. No clear seasonal pattern of IS cases emerged.

Conclusions: This study describes the epidemiology and estimates the incidence of IS in Latin American infants prior to the introduction of new rotavirus vaccines. The incidence of IS was found to vary between different countries, as observed in previous studies.

Trial registration: Clinical study identifier 999910/204 (SERO-EPI-IS-204).

Figure 1

Enrolled definite IS cases by country and study area residence (N = 476). During the study period, 517 potential IS cases in children under 2 years of age were identified. Mexico had the highest number of definite IS case reports (n = 113; 24%).

Figure 2

Overall age distribution of definite IS cases in Latin American infants (N = 476). IS cases presentation, (89%) occurred in the first year of life with a peak of cases between 4 and 8 months of age, and the highest number of cases seen among children aged 5 months.

Figure 3

Monthly distribution of definite IS cases (overall and in countries with >50 cases). Distribution of cases among months of the year, no clear seasonal pattern of cases emerged either overall or within individual countries with over 50 cases.

Figure 4

Annual incidence of definite IS in children under 1 year of age per 100,000 subjects. Lines indicate 95% confidence intervals. Figure shows that annual incidence of definite IS in children under 1 year of age ranged from 3.8 per 100,000 subjects in Brazil to 105.3 per 100,000 subjects in Argentina, with a wide variation in incidence.