Impact of Overactive Bladder Step Therapy Policies on Medication Utilization and Expenditures Among Treated Medicare...

The impact of formulary management strategies on utilization and expenditures in overactive bladder (OAB) treatment has not been extensively investigated. In 2013, step therapy (ST) policies for 2 branded OAB treatments, mirabegron and fesoterodine, were removed from Humana Medicare Advantage Prescription Drug (MAPD) plans and Medicare prescription drug plans (PDP), allowing for an examination of the effect of ST policies on OAB medication use patterns and costs.

To assess the impact of removal of formulary restriction policies for mirabegron and fesoterodine on medication utilization patterns and costs associated with OAB treatment in Medicare patients.

A retrospective cross-sectional study design was utilized. Subjects included individuals enrolled in Humana MAPD plans or PDPs, aged ≥ 65 years, with ≥ 1 prescription for an OAB medication in 2013. Patient demographic characteristics, OAB medication utilization, and pharmacy cost trends in 2013 were described. OAB medication use was calculated as the number of 30-day-supply equivalent medication claims and reported as a percentage of the total number of 30-day-supply equivalent claims across all OAB products. OAB medication expenditures were calculated as a percentage of the sum of pharmacy costs for OAB medications and reported separately for each month and drug during 2013. Temporal trends of OAB medication utilization and expenditures in 2013 were calculated using ordinary least squares regression.

Of 194,511 patients, trends in utilization of OAB medications indicated that on average, there was a statistically significant monthly increase in utilization of mirabegron (regression coefficient [B] = 274; P < 0.001; 95% CI: 218, 330), fesoterodine (B = 167; P < 0.001; 95% CI = 129, 205), oxybutynin extended release (ER; B = 357; P = 0.011; 95% CI = 99, 614), and trospium ER (B = 33; P = 0.001; 95% CI = 17, 50) and statistically significant decreases in utilization of solifenacin (B = -202; P = 0.048; 95% CI = -402, -2), tolterodine ER (B = -287; P = 0.002; 95% CI = -437, -137), darifenacin (B = -94; P < 0.001; 95% CI = -128, -61), and trospium immediate release (IR; B = -22; P = 0.001; 95% CI = -32, -12). Total OAB medication expenditures significantly increased an average of 0.12% for each month during the course of 2013 (B = 0.12; P = 0.026; 95% CI = 0.017, -0.223). While monthly oxybutynin IR utilization did not change significantly throughout 2013 (B = 228; P = 0.169; 95% CI = -114, -570), it demonstrated the largest average monthly expenditure increase (B = 0.082; P < 0.001; 95% CI = 0.056, 0.108). When removing oxybutynin IR costs from the total OAB medication costs, the trend in total OAB medication average monthly expenditures was not significant (B = 0.038; P = 0.365; 95% CI = -0.051, -0.126). An over 4-fold per-unit-cost increase for oxybutynin IR was noted.

Utilization of 2 branded OAB products increased in the months after ST removal with minimal cost impact. One of the possible reasons total OAB expenditures increased may have been due to the increased cost of the largest-volume generic product, oxybutynin IR.

This research was funded by Astellas Pharma Global Development and was conducted as part of the Astellas-Humana Research Collaboration. Ng, Kristy, Schermer, and Bradt are employees of Astellas. Astellas manufactures mirabegron (Myrbetriq) and solifenacin (VESIcare). Abbass, Caplan, Collins, and Suehs are employees of Comprehensive Health Insights, a subsidiary of Humana, which received funding from Astellas for this study. Suehs owns stock in Humana. Chan is an employee of Humana Pharmacy Solutions. Portions of this study were presented as a poster at Academy of Managed Care Pharmacy Nexus 2015; October 26-29, 2015; Orlando, Florida. Study concept and design were contributed by Ng, Chan, Suehs, and Abbass, along with Collins. Abbass took the lead in data collection, along with Collins and with assistance from Caplan, Chan, and Suehs. Data interpretation was provided by Kristy and Bradt, along with Abbass, Caplan, Ng, Suehs, Collins, and Chan. The manuscript was written primarily by Caplan, along with Schermer, Suehs, and Abbass, and revised by Caplan, Schermer, and Ng, along with the other authors.