Objective: To examine patterns of injury risk within sibling groups to determine whether a clinical encounter for injury care could be used as a marker to identify siblings at high risk for subsequent injury.
Study design: Children (n = 16,335; 0-15 years of age) enrolled in a health maintenance organization between 1995 and 1997 contributed 38,215 child-years of data. We tracked medically treated injuries that were diagnosed and classified as unintentional. Incidence rates and hazard ratios were calculated for children whose sibling had been injured in the previous 180 days compared with children without such exposure, adjusted for age, sex, sibling group size, and noninjury health care utilization.
Results: The 5,851 children had a total of 8,973 injuries. Injury incidence was 319 per 1,000 child-years among children with recent sibling injury and 235 per 1,000 child-years among children without this exposure (relative risk, 1.44; 95% CI, 1.36-1.53). When minor injuries were excluded, the adjusted relative risk was 1.95 (95% CI, 1.54-2.47).
Conclusions: Injury risk is shared within sibling groups and varies according to recent sibling injury experience. Clinical encounters for injury care might be used to identify sibling groups at increased injury risk.