Impact of New Medications and $4 Generic Programs on Overactive Bladder Treatment Among Older Adults in the United States, 2000-2015

Abstract

Background: Despite several new medications being Food and Drug Administration-approved for overactive bladder (OAB) and new prescription drug payment programs, there are limited population-based data regarding OAB medication use among older adults.

Objectives: To examine: (1) impacts of new medications and $4 generic programs on time trends for OAB-related medication dispensing for older adults in the United States; (2) differences by age and sex; and (3) temporal changes in OAB-related medication payments.

Methods: Using Truven Health Analytics' Medicare Supplemental Database (2000-2015), we analyzed OAB-related medication claims for 9,477,061 Medigap beneficiaries age 65-104. We estimated dispensing rates (per 1000 person-months), assessed dispensing trends using interrupted time-series methods, compared dispensing rates by age and sex, and summarized payment trends.

Results: From 2000 to 2015, 771,609 individuals filled 13,863,998 OAB-related prescriptions. During 2000-2007, 3 new extended-release medications became available (tolterodine, darifenacin, solifenacin), leading to increases in overall OAB-related dispensing rates by 19.1 (99% confidence interval, 17.0-21.2), a 92% increase since 2000; overall rates remained stable during 2008-2015. By 2015, the most common medications were oxybutynin (38%), solifenacin (20%), tolterodine (19%), and mirabegron (12%). Dispensing rates peaked at age 90 (rate, 53.4; 99% confidence interval, 53.1-53.7). Women had higher rates than men at all ages (average ratewomen-ratemen, 22.0). The gap between upper and lower percentiles of medication payments widened between 2008-2015; by 2015, 25% of reimbursed dispensed prescriptions had total payments exceeding $250.

Conclusions: Medication-specific dispensing rates for OAB changed when new alternatives became available. Recent changes in utilization and cost of OAB medications have implications for clinical guidelines, pharmacoepidemiologic studies, and payment policies.

FIGURE 1

Segmented trends over calendar time for dispensing rates (per 1000 person-months) of prescription medications for overactive bladder (OAB), among adults age 65–104 in the United States, 2000–2015. Trend segments (bold lines) and pointwise rates (faded jagged lines) are shown for all OAB medications combined (black) and each medication separately (colors). Pointwise rates were standardized to control for annual variation in geography and insurance plans included in the database. Trend estimates are listed for each segment below the plot for the change in rate (per 1000 person-months) per year of calendar time; trends are adjusted for seasonality using a transformed cosine periodic function and account for serial error autocorrelation using autoregressive model parameters. Interruptions are indicated by downward arrows and solid vertical lines. To relax linearity assumptions for trends during 2001–2003, a post hoc hinge point was added at week 114, halfway between interruptions 1 and 2 (dotted vertical lines). Rates for extended-release trospium and fesoterodine never exceeded 2.5 per 1000 person-months; therefore, they are not shown separately in the figure but are included in rates for all OAB medications combined. IR, immediate-release; ER, extended-release.

FIGURE 2

Dispensing rates (per 1000 person-months) with 99% confidence intervals, by gender and age, for all combined prescription medications for overactive bladder, among adults age 65–104 in the United States, 2000–2015. Rate differences are reported beneath the plot for age-group-specific comparisons between women versus men, with 99% bootstrap confidence intervals.

FIGURE 3

Payments per prescription over calendar time for prescription medications for overactive bladder, among adults age 65–104 in the United States, 2000–2015, adjusted for inflation to United States dollars ($) in 2015. (A) Beneficiary payments include deductible, coinsurance, copayment, and coordination of benefits. (B) Total payments include beneficiary payments and all post-discount payments by the insurer. Payment percentiles were calculated for each week of the study period, standardized by geography, and plotted using loess smoothers.