This is a paraphrased title for a paper Fusco et al. (2023). The authors conducted a systematic literature review of studies published between 2010 and 2020 and found that of the 79 articles screened:
Most publications found that increasing cost sharing was associated with poorer adherence, adherence, or discontinuation, regardless of disease area. Aggregated data suggest that the greater the cost-sharing, the lower the adherence. Among studies examining clinical outcomes, cost sharing was associated with poorer outcomes in 1 study, and no significant difference was found in the remaining 3 studies. About HRU [healthcare resource utilization], higher cost-sharing tends to reduce outpatient utilization and increase inpatient utilization. Available evidence suggests that higher cost sharing has an overall neutral or negative impact on total costs. Studies evaluating the elimination of copays have found total cost reductions or no impact.
Papers present two challenges of (i) publication bias and (ii) cost-sharing measurement. Regarding the former, are papers showing no relationship between cost allocation and adherence, HRU, and cost less likely to be published? Potential. While this bias may affect point estimates, it appears logically and empirically that higher cost allocations reduce adherence and increase hospital admissions. Publication bias may have had a greater impact on other measures, namely clinical outcomes and costs. A second challenge is that cost sharing may be measured differently in different studies. The authors do mention that the type and size of cost allocation varies from study to study. More importantly, however, the relationship between cost sharing and outcomes is difficult to estimate empirically because what one wants to measure is the cost sharing structure faced by patients; if you don’t fill a drug because the cost sharing is too high, the data The observed co-payment in will be $0, but the real cost-sharing one faces is large. On the other hand, if a person’s cost share is low, they may decide to fill the drug, and even if the benefit design is very generous, the observed cost share (as measured in the claim) will be high. Because claims data only includes amounts paid and not patient benefit structures, creative econometric solutions—or data that combines claims and benefit design—are needed to estimate the relationship between cost allocation and cost in a more rigorous manner . Nonetheless, by conducting a systematic literature review of these studies, Fusco and coauthors provide an important review for researchers to assess these issues in more detail for individual studies.
