Drug caps — the maximum number of prescriptions or drugs that a health plan will cover — and copayment policies can decrease overall drug use as well as insurers’ pharmacy spending, according to “Pharmaceutical policies: Effects of cap and copayment on rational drug use,” a study published in the Cochrane Database of Systematic Reviews.

Researchers combed through 21 studies that evaluated policies implemented by governments, not-for-profit agencies, and health insurance companies to evaluate five policies in which consumers pay directly for their drugs when they fill their prescription: caps, fixed copayments, tier copayments, coinsurance, and ceilings.

The researchers found reductions in drug use for both life-sustaining drugs and drugs that are important in treating chronic conditions. These policies tend to make consumers shoulder some of the cost of prescriptions, say the authors, and the cost could be a barrier to medication adherence, although the authors emphasize that patient outcomes were not included in the research.

The authors concluded that policies in which people pay directly for their drugs are less likely to cause harm if only non-essential drugs are included in these policies or exemptions are built into the policies to ensure that people receive needed medical care.