The Effect of Copayments for Prescriptions on Adherence to Prescription Medicines in Publicly Insured Populations; A Systematic Review and Meta-Analysis

Abstract

IntroductionCopayments are intended to decrease third party expenditure on pharmaceuticals, particularly those regarded as less essential. However, copayments are associated with decreased use of all medicines. Publicly insured populations encompass some vulnerable patient groups such as older individuals and low income groups, who may be especially susceptible to medication non-adherence when required to pay. Non-adherence has potential consequences of increased morbidity and costs elsewhere in the system.ObjectiveTo quantify the risk of non-adherence to prescribed medicines in publicly insured populations exposed to copayments.MethodsThe population of interest consisted of cohorts who received public health insurance. The intervention was the introduction of, or an increase, in copayment. The outcome was non-adherence to medications, evaluated using objective measures. Eight electronic databases and the grey literature were systematically searched for relevant articles, along with hand searches of references in review articles and the included studies. Studies were quality appraised using modified EPOC and EHPPH checklists. A random effects model was used to generate the meta-analysis in RevMan v5.1. Statistical heterogeneity was assessed using the I2 test; p>0.1 indicated a lack of heterogeneity.ResultsSeven out of 41 studies met the inclusion criteria. Five studies contributed more than 1 result to the meta-analysis. The meta-analysis included 199, 996 people overall; 74, 236 people in the copayment group and 125,760 people in the non-copayment group. Average age was 71.75years. In the copayment group, (verses the non-copayment group), the odds ratio for non-adherence was 1.11 (95% CI 1.09–1.14; P = <0.00001). An acceptable level of heterogeneity at I2 = 7%, (p = 0.37) was observed.ConclusionThis meta-analysis showed an 11% increased odds of non-adherence to medicines in publicly insured populations where copayments for medicines are necessary. Policy-makers should be wary of potential negative clinical outcomes resulting from non-adherence, and also possible knock-on economic repercussions.

Association of Copayment with Likelihood and Level of Adherence in New Users of Statins: A Retrospective Cohort Study

“…9,[12][13][14] We have attempted to bolster previous approaches by determining the increase in likelihood of adherence based on copayment using 2 distinct adherence thresholds and also by determining the incremental change in adherence caused by copayment in a retrospective cohort of new users of statins in the Veterans Health Administration (VHA).…”

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“…Co-payments were introduced as a revenue raising measure. Two Irish studies found both co-payments (€0.50 and €1.50) were associated with larger reductions in adherence to less--essential medicines than essential medicines, with anti-depressant and anxiolytic/hypnotic medicines being the exception [34,35]. In 2013, a number of cost containment measures were introduced.…”

The international generalisability of evidence for health policy: A cross country comparison of medication adherence following policy change

“…In contrast, a significant change in slope (-1.1%, 95% CI -1.9 to -0. 4) indicated that adherence fell in the months following the policy change (Table 2). …”

“…[1][2][3] Most studies have found that as the price of the copayment increases, patients reduce their adherence to essential life-prolonging drugs that are used in the treatment of chronic disease. [1,4,5] Copayments for prescription drugs are therefore directly and indirectly associated with increased morbidity, mortality and increased health care costs. [3,[6][7][8] While the results of previous research on copayments are mostly consistent, the majority of studies included in existing systematic reviews have been conducted in the U.S. and Canada.…”