In addition to the method above based on clinical judgment, we also used a method based on survey responses to identify activity-limiting conditions. A subset of potentially disabling chronic conditions highly correlated with disability was identified in LaPlante's (1989) analysis of the National Health Interview Survey. In LaPlante'sanalyses, disability was based upon limitations in daily activities or work, or the inability to work. He determined the most common chronic conditions, in terms of disability risk, for children and adults in 1983-1986. Those conditions are noted in the fourth column of Appendices A-1 through A-4 of this report. In the Private Payers Study, people with these activity-limiting conditions were identified on the basis of their ICD-9-CM diagnosis or condition codes. Chapter 5 notes that, depending upon the plan type considered, about 30-60 percent of the analytic sample members used in the empirical analyses for the Private Payers Study had one or more of the activity-limiting conditions.
LaPlante's conditions for children and adults differ from each other for the most part, as may be seen in Appendices A-1 through A-4. Only four conditions appear among the top 20 for both children and adults: mental retardation, cerebral palsy, epilepsy, and other heart conditions. For both age groups, mental retardation was the condition most likely to lead to disability. Musculoskeletal impairments appeared to be more common among adults, while asthma and impediments of speech and hearing appeared to be more problematic for children. Because of these differences, analyses of children and adults were conducted separately in the Private Payers Study.