Formulary restrictions discourage adherence to medications
Money saved up front through tight formulary management, might be spent several times over later because of poor outcomes that will boost overall costs, according to a study in the Journal of Managed Care Pharmacy. Studies published in 1993 or later are included in this systematic literature review if they assess the impact of formulary restrictions on outcomes in the United States. The authors aggregate the impact of various formulary restrictions (cost-sharing, prior authorization, step therapy, preferred drug list, and quantity limit) on various types of outcome (medication adherence, clinical outcomes, economic outcomes, and health care resource utilization).
Ninety three studies having a total of 262 outcomes are included in the analysis. The two most frequently studied formulary restrictions are cost-sharing and prior authorization. Meanwhile step therapy, preferred drug lists, and quantity limits are each less than 10% of the total formulary restrictions.
The authors group the 262 outcomes into four categories in which medication adherence accounts for 45.8% of these outcomes, while health care resource utilization, economic outcomes, and clinical outcomes account for 27.5%, 22.5%, and 4.2%, respectively. They also perform a separate breakdown of the 262 outcomes by measuring what good, if any, the formulary restrictions did the patients. It turns out that 49.6% are negative, 36.3% are neutral, and 14.1% are positive.
The authors note that 68.3% of the medication adherence outcomes are negative, 50% of the health care resource utilization outcomes are neutral, and there is an equal distribution among negative, neutral, and positive for the two remaining outcomes (clinical and economical outcomes). These results are in the graph below.
The authors conclude that of the four types of outcome, medication adherence is the only one negatively affected by formulary restrictions. Meanwhile, there was no distinct association between formulary restrictions and the other three outcomes, namely health care resource utilization, economic outcomes, and clinical outcomes.
The authors recognize that a limitation of this study is inclusion of only 20 studies of prior authorization and eight studies of step edits to determine their effects on medication adherence, clinical outcomes, economic outcomes, and health care resource utilization. Seeing this makes one wonder why the effects of these widely used formulary restrictions haven’t been studied as much.