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Keywords:

  • adherence;
  • compliance;
  • Cox proportional hazard model;
  • logistic regression model;
  • overactive bladder

ABSTRACT

Objectives:  To investigate persistence and adherence of medication treatment in chronic overactive bladder/urinary incontinence (OAB/UI) patients, and to evaluate OAB/UI-related comorbidity events associated with persistence.

Methods:  Pharmaceutical outcomes research with a health-care provider perspective was conducted on a California Medicaid (Medi-Cal) chronic OAB/UI population. The primary end point was medication possession ratio (MPR), which was used to measure refill adherence. Secondary end points measuring persistence patterns included discontinuation of OAB drug therapy (medication-uncovered interval > 30 days) and time to discontinuation  (period  from  the  index  date  until  the first discontinuation date). Significant factors on nonpersistence were found by using a Cox Proportional Hazards model. Factors contributing to nonadherence (MPR < 0.8) and the relationship between OAB/UI comorbidity events and persistence were examined by logistic regressions.

Results:  Of 2496 eligible patients, 36.9% had only one OAB/UI prescription. The mean MPR was 0.34 (SD 0.21) and the median was 0.3, indicating that on average only about one-third of period of time since medication initiation was covered by the therapy. Only 122 patients exhibited > 80% adherence during the 6-month follow-up-period. Significant predictors of higher persistence included: white ethnicity, previous hospitalization length, starting with tolterodine or oxybutynin extended-release, and previous use of topical drugs or antipsychotics. Nevertheless, previous depression or urinary tract infection (UTI) diagnosis, polypharmacy, significantly increased the odds of early discontinuation. Treatment discontinuation increased the risk of UTI diagnosis by 37% in the post-treatment period (= 0.03; OR 1.37; 95% CI 1.03–1.84), but had no significant effect on other OAB/UI-related comorbidities.

Conclusions:  For chronic OAB/UI patients identified in this study, both persistence and adherence with medication treatment were suboptimal. These results suggest that persistence and treatment discontinuation remains problematic for the OAB/UI population.