Background: Many patients are burdened by prescription costs, and patients, providers and policy makers may attempt to reduce these costs by substituting 3-month for 1-month supplies of medicines.
Objectives: To measure the difference in out-of-pocket and total costs among patients receiving different quantities of the same prescription drug used to treat a chronic condition, and to examine patient and health system characteristics associated with the use of a 3-month supply.
Methods: Data were pooled from the 2000–5 Medical Expenditure Panel Survey, a nationally representative survey of the US non-institutionalized civilian population, to compare prescription drug expenditures for medicines dispensed as both 3-month and 1-month supplies. Logistic regression was used to model correlates associated with 3-month use. The main outcome measures were the mean monthly out-of-pocket and total costs expressed in year 2005 values.
Results: Forty-four percent of prescriptions examined were dispensed as 3-month supplies. The average (95% CI) monthly total and out-of-pocket costs for a 1-month supply were $US42.72 (42.01, 43.42) and $US20.44 (19.99, 20.89), respectively, while the corresponding monthly costs for a 3-month supply were $US37.95 (37.26, 38.64) and $US15.10 (14.68, 15.53). After adjustment for potential confounders, this represented a 29% decrease in out-of-pocket costs and an 18% decrease in total prescription costs through the use of a 3-month rather than a 1-month supply. Eighty percent of patients achieved some cost savings from a 3-month supply and there was considerable variation in the amount saved. There were no marked differences in the characteristics of individuals using 3-month versus 1-month supplies.
Conclusions: Although such opportunities are not universally available, these findings quantify the cost savings that patients in the US can achieve through filling larger quantities of a prescription for a chronic condition.