Copayments and Quality of Care

A new piece of research reported in the Journal of the American Medical Association tries to ascertain whether cost-sharing deters people from adhering with medication therapy and whether such lack of adherence may be associated with worse clinical outcomes.   (JAMA Article)   The researchers focused on a specific medication which is recommended after a heart attack to reduce the risk of repeat episodes.  These are fairly expensive drugs, and adherence to therapy had previously been found to be suboptimal.  Cost is theorized to be one reason that patients fail to follow recommended treatment.  Copays for these medications can range from $50 per month to $200 or even over $300.  The trial was designed to provide copay vouchers to patients and see what the effect was.  300 hospitals were randomized to their patients either receiving or not receiving the vouchers, with 135 in the intervention group and the rest in the control arm.  The vouchers reduced the cost of the medicine to zero, which should mean cost would not be a reason for non-adherence.  The primary endpoints were medication persistence and compliance and the rate of major adverse cardiovascular events.  About 11,000 patients ended up being included in the analysis, and 10,000 of those were discharged from hospital alive with a prescription for the relevant drugs.

87% of patients in the intervention group reported being compliant with the medication regimen, compared to 83.8% in the control arm, a small but statistically significant difference.  Using pharmacy fill data and laboratory results suggested higher compliance rates and a larger difference between groups, but still relatively small.  It is somewhat surprising to me that the difference was that small, it suggests cost was not much of a deterrence to adherence.  On an unadjusted basis, 10.2% of patients in the intervention group had a subsequent major adverse cardiovascular event, compared to 10.6% in the control group, but even that minor difference disappeared after adjustment for patient characteristics.  This suggests that the slightly improved adherence had no real clinical outcomes impact.  One explanation may be that even in the intervention group some patients did not use the voucher, but I don’t see how that changes the fact that clinical outcomes were not different.  The authors appear to resist the most obvious interpretation, that the drugs don’t have the advertised beneficial effects.  It would seem to me that perhaps the recommendation to use these expensive medications should be revisited.