Impact of a step-therapy protocol for pregabalin on healthcare utilization and expenditures in a commercial population

Abstract

Objective: To compare changes in healthcare resource utilization and costs among members with painful diabetic peripheral neuropathy (pDPN), postherpetic neuralgia (PHN), or fibromyalgia (FM) in a commercial health plan implementing pregabalin step-therapy with members in unrestricted plans.

Methods: Retrospective study of outcomes associated with implementation of a pregabalin step-therapy protocol using claims data from Humana ('restricted' cohort) and Thomson Reuters MarketScan ('unrestricted' cohort). Members aged 18-65 years receiving treatment for pDPN, PHN, or FM during 2008 or 2009 were identified; cohorts were matched on diagnosis and geographic region. Baseline to follow-up changes in healthcare resource utilization and costs were determined using difference-in-differences (DID) analysis. Statistical models adjusting for covariates explored relationships between restricted access and outcomes.

Results: A total of 3876 restricted cohort members were identified and matched to 3876 unrestricted cohort members. FM was the predominant diagnosis (84.7%). The unrestricted cohort was older (mean = 49.0 (SD = 10.4) years vs 47.6 (SD = 10.5) years; p < 0.001), and had greater comorbidity (RxRisk-V score = 5.4 (SD = 3.2) vs 4.4 (SD = 2.9), p < 0.001) than the restricted cohort. Compared with the unrestricted cohort, the restricted cohort demonstrated a greater year-over-year decrease in pregabalin utilization (-2.6%, p = 0.008), and greater increases in physical therapy and disease-related outpatient utilization (3.7%, p = 0.010 and 3.6%, p = 0.022, respectively). There were no statistically significant net differences in all-cause or disease-related total healthcare, medical, or pharmacy costs between cohorts. After adjusting for baseline compositional differences between cohorts, restricted plan membership was associated with a net increase in all-cause medical ($1222; p = 0.016) and disease-related healthcare costs ($859; p = 0.002). Limitations include use of a combined analysis for pDPN, PHN, and FM, especially since the observed results were likely driven by FM; an inability to link the prescribing of a medication with the condition of interest, which is common to claims analyses; and lack of pain severity information.

Conclusions: Implementation of a pregabalin step-therapy protocol resulted in lower pregabalin utilization, but this restriction was not associated with reductions in total healthcare costs, medical costs, or pharmacy costs.