Do children whose families bear a percentage of their health care costs reduce their use of ambulatory care compared with those families who receive free care? If so, does the reduction affect their health? To answer these questions, 1,844 children aged 0 to 13 years were randomly assigned (for a period of 3 or 5 years) to one of 14 insurance plans. The plans differed in the percentage of their medical bills that families paid. One plan provided free care. The others required up to 95% coinsurance subject to a +1,000 maximum. Children whose families paid a percentage of costs reduced use by up to one third. For the typical child in the study, this reduction caused no significant difference in either parental perceptions of their child's health or in physiologic measures of health. Confidence intervals are sufficiently narrow for most measures to rule out the possibility that large true differences went undetected. Nor were statistically significant differences observed for children at risk of disease. Wider confidence intervals for these comparisons, however, mean that clinically meaningful differences, if present, could have been undetected in certain subgroups.

Does free medical care lead to better health than insurance plans that require the patient to shoulder part of the cost? In an effort to answer this question, we studied 3958 people between the ages of 14 and 61 who were free of disability that precluded work and had been randomly assigned to a set of insurance plans for three or five years. One plan provided free care; the others required enrollees to pay a share of their medical bills. As previously reported, patients in the latter group made approximately one-third fewer visits to a physician and were hospitalized about one-third less often. For persons with poor vision and for low-income persons with high blood pressure, free care brought an improvement (vision better by 0.2 Snellen lines, diastolic blood pressure lower by 3 mm Hg); better control of blood pressure reduced the calculated risk of early death among those at high risk. For the average participant, as well as for subgroups differing in income and initial health status, no significant effects were detected on eight other measures of health status and health habits. Confidence intervals for these eight measures were sufficiently narrow to rule out all but a minimal influence, favorable or adverse, of free care for the average participant. For some measures of health in subgroups of the population, however, the broader confidence intervals make this conclusion less certain.

This paper offers suggestions to adi the selection of appropriate instruments and data gathering methods for studies that require measures of personal health status applicable in general populations. Before selecting measures, the reason for studying health status must be identified. Next, definitional issues arise when attempting to specify the components of health that are to be studied. Evidence supports restriction of the definition of personal health status to its physical and mental components, rather than including social circumstances as well. In evaluating the suitability of available measures, three features must be considered: 1) practicality in terms of administration, respondent burden, and analysis; 2) reliability in terms of the study design and group or individual comparisons; 3) validity, in terms of providing information about the particular health components of interest to the study. Evaluating validity will be difficult for most available measures; careful attention to item content will be helpful in choosing appropriate measures. Despite problems in development and interpretation, overall health status indicators will prove useful to many studies and should be considered, as should both subjective and objective measures of health status. Given that the reasons to measure health have been identified, the aspects of health to be measured specified, and attention paid to their suitability, appropriate measures may often be found among those now available.