Health insurance coverage within sibships: prevalence of mixed coverage and associations with health care utilization.

An increasing proportion of children in the United States lives in families with complicated family structures and a mix of immigrant and US-born family members. Eligibility rules for health insurance coverage, however, were not designed with these families in mind. The result can be complicated insurance patterns among siblings within families, with some "sibships" only being partially-insured, and other sibships having both private and public coverage. We hypothesize that mixed coverage among siblings causes confusion and logistical difficulties for parents and may lead to less access to appropriate health care for their children. In this article, we use data from the 2009-2011 National Health Interview Survey (n = 51,418 children in 20,478 sibships) to present estimates of the prevalence of mixed health insurance coverage among siblings and describe the predictors of such coverage. We also use linked data from the 2001-2005 National Health Interview Survey and 2002-2007 Medical Expenditure Panel Survey (n = 17,871) to show how mixed coverage is related to health care utilization. We find that although few sibships are characterized by different health insurance coverage types, mixed coverage among siblings is far more common among families with mixed nativity status, and blended families with step- and half-siblings. In terms of outcomes, children living in sibships with mixed coverage have significantly lower odds of having a usual source of health care. We also consider whether the association between mixed insurance coverage and health care outcomes differs across particular combinations of insurance coverage. We find that both publicly-insured children who have uninsured siblings and privately-insured children with publicly-insured siblings are less likely to have a usual source of care than similar children with uniformly-insured siblings. Because a usual source of care is associated with better health care outcomes, we argue that policymakers should consider ways to reduce mixed coverage among children and families.