A systematic umbrella review of the association of prescription drug insurance and cost-sharing with drug use, health services use, and health

BACKGROUND: Increasing spending and use of prescription drugs pose an important challenge to governments that seek to expand health insurance coverage to improve population health while controlling public expenditures. Patient cost-sharing such as deductibles and coinsurance is widely used with aim to control healthcare expenditures without adversely affecting health. METHODS: We conducted a systematic umbrella review with a quality assessment of included studies to examine the association of prescription drug insurance and cost-sharing with drug use, health services use, and health. We searched five electronic bibliographic databases, hand-searched eight specialty journals and two working paper repositories, and examined references of relevant reviews. At least two reviewers independently screened the articles, extracted the characteristics, methods, and main results, and assessed the quality of each included study. RESULTS: We identified 38 reviews. We found consistent evidence that having drug insurance and lower cost-sharing among the insured were associated with increased drug use while the lack or loss of drug insurance and higher drug cost-sharing were associated with decreased drug use. We also found consistent evidence that the poor, the chronically ill, seniors and children were similarly responsive to changes in insurance and cost-sharing. We found that drug insurance and lower drug cost-sharing were associated with lower healthcare services utilization including emergency room visits, hospitalizations, and outpatient visits. We did not find consistent evidence of an association between drug insurance or cost-sharing and health. Lastly, we did not find any evidence that the association between drug insurance or cost-sharing and drug use, health services use or health differed by socioeconomic status, health status, age or sex. CONCLUSIONS: Given that the poor or near-poor often report substantially lower drug insurance coverage, universal pharmacare would likely increase drug use among lower-income populations relative to higher-income populations. On net, it is probable that health services use could decrease with universal pharmacare among those who gain drug insurance. Such cross-price effects of extending drug coverage should be included in costing simulations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12913-022-07554-w.