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Am J Manag Care. 2005 Nov;11(11):730-40.

The effects of prescription drug cost sharing: a review of the evidence.

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  • 1Medstat, 777 E Eisenhower Parkway, Ann Arbor, MI 48108, USA.



To determine whether patients respond to increased cost sharing by substituting less expensive alternatives for medications with higher levels of copayments or coinsurance, and to examine the body of evidence on the relationships between cost sharing and use of essential or maintenance medications, health outcomes, process-of-care measures (such as medication adherence and discontinuation), and costs.


Literature review.


Healthcare reference databases and key journals were searched to identify peer-reviewed empirical studies that examined the effects of variation in the amount of prescription drug copayments or coinsurance on healthcare utilization patterns. Thirty studies met our search criteria.


Higher levels of prescription drug cost sharing generally produce intended effects, namely, decreasing the consumption of prescription drugs and steering patients away from nonpreferred to preferred brand-name drugs. However, patients do not always switch to generic drugs. Although not consistently reported, the most troublesome effects associated with higher levels of cost sharing are treatment disruptions (such as lower levels of treatment adherence, continuation, and initiation) for chronically ill patients. At times, higher levels of cost sharing can affect the use of essential medications and outcomes of care.


Cost sharing reduces the consumption of prescription drugs but may have unintended effects on the process and outcomes of therapy. Further research is warranted in this area. The central question for health plan managers and policy makers is whether we will continue to use cost sharing as is or make modifications to reduce unintended effects.

[PubMed - indexed for MEDLINE]
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