Formulary Restrictions May Result in Short-Term Savings, But Also Suboptimal Patient Care

Formulary benefits are generally designed with the intention of lowering costs, typically by encouraging the increased use of generic medications and restricting the use of brand medications or other treatments. Yet these restrictions in formulary benefit designs also can have the unintended consequence of increasing spending on medical and hospital care, negating the “savings” achieved through generic utilization. What does this mean for patients, especially in diabetes care?

A poster presentation, “Building the Evidence Base for Evaluating Complex Drug Formulary Designs in Type 2 Diabetes Mellitus,” (#892) will illustrate findings from a National Pharmaceutical Council and University of Maryland School of Pharmacy study that examined the effect of formulary restrictions on the use of drugs that counteract high levels of glucose in the blood without using insulin, also known as non-insulin antihyperglycemic agents.

The researchers identified low-income subsidy Medicare beneficiaries who were diagnosed with type 2 diabetes mellitus and were using metformin, an oral diabetes medicine that helps control blood sugar levels, as baseline therapy. They were randomly assigned to one of 17 benchmark formularies.

Four possible formulary restrictions for each agent were identified: quantity limit (i.e., pills per month), prior authorization, step therapy or formulary exclusion. The beneficiaries were categorized according to their drug exposure (i.e., metformin only, metformin plus Dipeptidyl peptidase-4 (DPP4), metformin plus sulfonylurea, metformin plus other antihyperglycemic agent). For each formulary, the researchers calculated the distribution of beneficiaries across the four categories of drug utilization and examined the associated formulary restrictiveness.

Researchers concluded that restrictions placed on non-insulin antihyperglycemic agents, which are commonly used in combination with metformin, are associated with higher use of metformin only or metformin in combination with sulfonylurea, which are largely generic. This means that beneficiaries are less likely to receive the branded class of DPP4.

The bottom line is that when formularies restrict commonly used drugs to manage chronic disease, in this case shifting from an effective antihyperglycemic combination therapy to metformin only, medical and hospital care expenses could potentially increase – despite short-term cost savings to the payer – because of suboptimal hyperglycemic control, which harms the patient in the end.

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