Pharmaceutical policies: effects of cap and co-payment on rational use of medicines

Growing expenditures on prescription medicines represent a major challenge to many health systems. Cap and co-payment policies are intended as an incentive to deter unnecessary or marginal utilisation, and to reduce third-party payer expenditures by shifting parts of the financial burden from insurers to patients, thus increasing their financial responsibility for prescription medicines. Direct patient payment policies include caps (maximum numbers of prescriptions or medicines that are reimbursed), fixed co-payments (patients pay a fixed amount per prescription or medicine), co-insurance (patients pay a percentage of the price), ceilings (patients pay the full price or part of the cost up to a ceiling, after which medicines are free or are available at reduced cost) and tier co-payments (differential co-payments usually assigned to generic and brand medicines). This is the first update of the original review.

To determine the effects of cap and co-payment (cost-sharing) policies on use of medicines, healthcare utilisation, health outcomes and costs (expenditures).

For this update, we searched the following databases and websites: The Cochrane Central Register of Controlled Trials (CENTRAL) (including the Cochrane Effective Practice and Organisation of Care (EPOC) Group Specialised Register, Cochrane Library; MEDLINE, Ovid; EMBASE, Ovid; IPSA, EBSCO; EconLit, ProQuest; Worldwide Political Science Abstracts, ProQuest; PAIS International, ProQuest; INRUD Bibliography; WHOLIS, WHO; LILACS), VHL; Global Health Library WHO; PubMed, NHL; SCOPUS; SciELO, BIREME; OpenGrey; JOLIS Library Network; OECD Library; World Bank e-Library; World Health Organization, WHO; World Bank Documents & Reports; International Clinical Trials Registry Platform (ICTRP), WHO; ClinicalTrials.gov, NIH. We searched all databases during January and February 2013, apart from SciELO, which we searched in January 2012, and ICTRP and ClinicalTrials.gov, which we searched in March 2014.

We defined policies in this review as laws, rules or financial or administrative orders made by governments, non-government organisations or private insurers. We included randomised controlled trials, non-randomised controlled trials, interrupted time series studies, repeated measures studies and controlled before-after studies of cap or co-payment policies for a large jurisdiction or system of care. To be included, a study had to include an objective measure of at least one of the following outcomes: medicine use, healthcare utilisation, health outcomes or costs (expenditures).

Two review authors independently extracted data and assessed study limitations. We reanalysed time series data for studies with sufficient data, if appropriate analyses were not reported.

We included 32 full-text articles (17 new) reporting evaluations of 39 different interventions (one study - Newhouse 1993 - comprises five papers). We excluded from this update eight controlled before-after studies included in the previous version of this review, because they included only one site in their intervention or control groups. Five papers evaluated caps, and six evaluated a cap with co-insurance and a ceiling. Six evaluated fixed co-payment, two evaluated tiered fixed co-payment, 10 evaluated a ceiling with fixed co-payment and 10 evaluated a ceiling with co-insurance. Only one evaluation was a randomised trial. The certainty of the evidence was found to be generally low to very low.Increasing the amount of money that people pay for medicines may reduce insurers' medicine expenditures and may reduce patients' medicine use. This may include reductions in the use of life-sustaining medicines as well as medicines that are important in treating chronic conditions and medicines for asymptomatic conditions. These types of interventions may lead to small decreases in or uncertain effects on healthcare utilisation. We found no studies that reliably reported the effects of these types of interventions on health outcomes.

The diversity of interventions and outcomes addressed across studies and differences in settings, populations and comparisons made it difficult to summarise results across studies. Cap and co-payment polices may reduce the use of medicines and reduce medicine expenditures for health insurers. However, they may also reduce the use of life-sustaining medicines or medicines that are important in treating chronic, including symptomatic, conditions and, consequently, could increase the use of healthcare services. Fixed co-payment with a ceiling and tiered fixed co-payment may be less likely to reduce the use of essential medicines or to increase the use of healthcare services.