Operationalizing a conceptually based noncategorical definition: a first look at US children with chronic conditions.

OBJECTIVE: To apply a conceptually based noncategorical definition in the analysis of a nationally representative sample of US children to determine the prevalence and sociodemographic characteristics of US children with chronic conditions.
DESIGN: Data on 30032 children, aged 0 through 17 years, from the 1994 National Health Interview Survey Disability Supplement were analyzed using a noncategorical conceptual definition of chronic conditions and a method that parallels that outlined in the development of the Questionnaire for Identifying Children with Chronic Conditions. We determined the percentages of children with chronic conditions overall and in 3 conceptual domains: (1) functional limitations, (2) dependence on compensatory mechanisms, and (3) service use or need beyond routine care for age.
RESULTS: Content that corresponded to 35 of 39 items on the Questionnaire for Identifying Children with Chronic Conditions assessing consequences was available in the National Health Interview Survey Disability Supplement data set. An estimated 10.3 million children (14.8%) had chronic conditions; 7.0% of the children met enrollment criteria in a single conceptual domain, 5.2% in 2 domains, and 2.6% in all 3 domains. Significant sociodemographic correlates of having a chronic condition were being school-aged or older, male, white, living with a responsible adult with less than a college education, and having a family income below the poverty index (all P<.01).
CONCLUSIONS: We established the feasibility of operationalizing a noncategorical conceptual definition by using a large-scale data set and provided an estimate of the prevalence of chronic conditions among US children. We confirmed that several sociodemographic correlates of chronic conditions in samples identified through diagnostic checklists were related to the presence of chronic conditions among these children.