Drug insurance instability and its correlates: results from the 2000 Medical Expenditure Panel Survey

Health insurance instability (ie, temporal gaps in health insurance coverage) is a prevalent phenomenon in the United States. To date, most studies have focused on the factors that affect the intermittent lack of health insurance coverage. However, no studies known to the authors have examined the factors associated with prescription drug insurance instability (ie, temporal gaps in drug insurance coverage) among working-age adults. Developing an accurate profile of persons with unstable drug insurance is essential to formulate rational policy to address this problem.

The objectives of this study were to (1) document the prevalence of prescription insurance instability among working-age adults and (2) describe the association between prescription drug insurance instability and demographic, socioeconomic status, and employment characteristics.

The data source used in this study was the 2000 Medical Expenditure Panel Survey. This study used a cross-sectional design using data provided by respondents at each of the 3 interviews conducted during the year 2000. Chi-square and hierarchical multinomial logistic regression analyses were used to describe the associations among (1) demographics, (2) socioeconomic status, and (3) employment characteristics and drug insurance status (classified as continuous, absent, or unstable).

During the year 2000, 12.5% (21.1 million) of the working-age adults in the United States had unstable prescription drug coverage. Persons aged 35-54 years had lower rates of drug insurance instability compared with those aged 18-24 [adjusted odds ratio 0.66 (95% confidence interval 0.54-0.80)]. The least educated (12 or fewer years of education) were more likely than those with more education (13-16 years) to experience at least one period without drug coverage (62% vs 32%, P<0.01). The poorest respondents (those at less than 200% of the federal poverty level) were more likely than the wealthiest respondents (those at more than 400% of the poverty level) to report at least some time without drug coverage (37% vs 28%, P<0.01). Those experiencing a divorce or death of a spouse were more than twice as likely as stably married persons to experience at least one period without drug insurance [adjusted odds ratio 2.23 (95% confidence interval 1.68-2.96)]. Adults who were unstably employed during the year and/or who worked for small firms generally experienced higher rates of drug insurance instability.

Prescription drug insurance instability is a prevalent phenomenon among working-age adults in the United States, with approximately 1 in 8 experiencing this problem during 2000. Our results suggest that demographics, socioeconomic status, and employment characteristics all play important roles in predicting prescription drug insurance status, with the least educated and poorest being particularly vulnerable to interruptions in drug coverage. Premium assistance programs providing subsidies to small firms' low-income employees and permitting small firms to form insurance pools may help to decrease the number of drug coverage uninsurance spells in this population.