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Supplements New Perspectives on Overactive Bladder: Quality of Life Impact, Medication Persistency, and Treatmen
New Perspectives on Overactive Bladder: Quality of Life Impact, Medication Persistency, and Treatment Costs
C. Daniel Mullins, PhD; and Leslee L. Subak, MD
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Persistence With Overactive Bladder Pharmacotherapy in a Medicaid Population
Fadia T. Shaya, PhD, MPH; Steven Blume, MS; Anna Gu, MA; Teresa Zyczynski, PharmD, MBA, MPH; and Zhanna Jumadilova, MD, MBA
Safety and Tolerability of Tolterodine for the Treatment of Overactive Bladder in Adults
Richard G. Roberts, MD, JD; Alan D. Garely, MD; and Tamara Bavendam, MD
Medical Costs After Initiation of Drug Treatment for Overactive Bladder: Effects of Selection Bias on Cost Estimates
Nicole M. Nitz, PhD; Zhanna Jumadilova, MD, MBA; Theodore Darkow,   PharmD; Jennifer R. Frytak, PhD; and Tamara Bavendam, MD
Economic Impact of Extended-release Tolterodine versus Immediate-and Extended-release Oxybutynin Among Commercially Insured Persons With Overactive Bladder
Sujata Varadharajan, MS; Zhanna Jumadilova, MD, MBA; Prafulla Girase, MS; and Daniel A. Ollendorf, MPH
Urinary Incontinence in the Nursing Home: Resident Characteristics and Prevalence of Drug Treatment
Zhanna Jumadilova, MD, MBA; Teresa Zyczynski, PharmD, MBA, MPH; Barbara Paul, MD; and Siva Narayanan, MS, MHS
Treatment of Overactive Bladder: A Model Comparing Extended-release Formulations of Tolterodine and Oxybutynin
Eleanor M. Perfetto, PhD; Prasun Subedi, MS; and Zhanna Jumadilova, MD, MBA
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Persistence With Overactive Bladder Pharmacotherapy in a Medicaid Population

Fadia T. Shaya, PhD, MPH; Steven Blume, MS; Anna Gu, MA; Teresa Zyczynski, PharmD, MBA, MPH; and Zhanna Jumadilova, MD, MBA

To determine whether differences in persistence by drug are statistically significant after adjusting for age, sex, and race, a time-dependent Cox model was constructed that allowed different HRs before and after the critical 30-day mark. Using the Cox model without controlling for covariates, and only the time variable, results showed that oxybutynin IR had a significantly higher rate of discontinuation than tolterodine ER within the first 30 days (HR = 1.25; 95% confidence interval [CI], 1.01-1.53). After this initially poorer start, oxybutynin IR users discontinue at statistically the same rate as tolterodine ER users. This corresponds to the unadjusted survival curve.

In a Cox model adjusting for age (<18 years, 18-40 years, >40 years), sex, and race (Caucasian, African American, other), oxybutynin IR is not significantly different from tolterodine ER (HR = 1.09; 95% CI, 0.88-1.35) in the initial 30-day period (Table 2). Table 2 shows the HRs of non-persistence of oxybutynin IR and oxybutynin ER compared with tolterodine ER. Because of the large drop in persistence for any of the 3 drugs in the first 30 days, the analysis is stratified by time period, differentiating between trends in the first 30 days and trends in the period after 30 days. The effects are also shown on nonpersistence of age, sex, and race. In the first 30 days, the oxybutynin ER and tolterodine ER do not differ statistically, in both adjusted (HR = 0.96; 95% CI, 0.60-1.53) and unadjusted models (HR = 1.04; 95% CI, 0.80-1.35). However, of the users who continue past 30 days, oxybutynin ER has a higher risk of discontinuation in both the adjusted (HR = 1.47; 95% CI, 1.01-2.14) and unadjusted models (HR = 1.50; 95% CI, 1.03-2.18).

Figure

Possession Time. The survival curves for patient possession time with an MPR >30% are shown by index drug in Figure 2. About 45% of those starting on oxybutynin IR and 55% of those starting on either tolterodine ER or oxybutynin ER maintain possession after 30 days. At 1 year, 16%, 22%, and 15% are maintaining possession of oxybutynin IR, tolterodine ER, and oxybutynin ER, respectively. The shape of the possessiontime survival curve points to a time-dependent model that can handle different HRs before and after 30 days of possession time.

Figure

No drug shows significantly different hazard risk than another in either time period, in both unadjusted and adjusted Cox models. Detailed HR results are included in Table 2.

In a comparison of the distributions for persistence and possession time, it was found that possession time is just 30 days longer than persistence for 80% of patients. On average, tolterodine ER and oxybutynin ER users possess medication approximately 40 days longer than they persist. The mean difference is greater for oxybutynin IR users, which is approximately 60 days.

Switching. About 6% of the cohort switched drugs before they were determined to be otherwise nonpersistent or reached the end of the enrollment period, with little difference by index drug. Of those who did switch, 44%, 56%, and 20% (tolterodine ER, oxybutynin ER, and oxybutynin IR, respectively) switched in the first 30 days. The corresponding rates by 120 days were 50%, 80%, and 60%.

Demographic and Clinical Predictors. Table 2 includes HRs from the Cox multivariate model, indicating how age, race, and sex affect persistence and possession time. Younger patients are half as likely to discontinue their original therapy compared with young adults aged 18 to 39 years (HR = 1.56; 95% CI, 1.33-1.82). Patients aged 40 to 64 years are significantly less likely to discontinue therapy than the younger adults (HR = 0.85; 95% CI, 0.74-0.97). Age has a similar effect on possession time.

African Americans and other minorities were more likely than Caucasians to discontinue or switch (HR = 1.22; 95% CI, 1.09- 1.36). At 90 days, only 15% of African Americans remain persistent compared with 27% of Caucasians. Similar racial effects held for possession time. Sex did not affect long-term persistence; however, an interesting difference shows up in the first 30 days. If men were going to discontinue, they were more likely than women to stop therapy in the first 30 days (HR = 1.16; 95% CI, 1.01-1.34). Men who continue past 30 days are less likely than women to stop (HR = 0.74; 95% CI, 0.56-0.94).

As might be expected, patients who had a qualified diagnosis for OAB in the 6 months before initiating medication were less likely to discontinue than others (HR = 0.80; 95% CI, 0.72-0.89; n = 715).

Discussion

Because patients eligible for Medicare were excluded and there is a high prevalence of children in most Medicaid plans, the cohort of OAB patients identified here was younger than what might be expected in terms of more typical OAB patients. Among the 3 products of interest, oxybutynin IR use is predominant at 76% of users. This is likely a result of the preferred use of generic drugs as a cost-containment measure in many Medicaid plans.

Rates of persistence with OAB drugs were found to be low among these Medicaid MCO patients, with only 32% of the oxybutynin IR users and 44% of users of either once-daily agent refilling their first prescription at 30 days. The difference is associated with the greater number of young adults in the oxybutynin IR cohort, whose persistence is significantly less than older adults. Of those patients who did fill a second prescription, persistence was significantly better for patients receiving tolterodine ER compared with oxybutynin ER; the significant difference persists after adjusting for demographic variables (HR = 1.47; 95% CI, 1.01-2.14). In 2 clinical trials comparing the 2 longeracting agents over a 12-week period, results on relative efficacy were mixed, whereas fewer tolterodine ER users experienced dry mouth than did oxybutynin ER users.17,18 Thus, this difference may be a result of fewer patients experiencing adverse effects, such as dry mouth; however, a specific study that tests this hypothesis would be needed for confirmation.

After the initially poorer persistence for oxybutynin IR users, those who do continue after 30 days adhere at about the same rate as tolterodine ER users. It is possible that these patients experience more side effects at the initiation of therapy. However, those who do not experience these side effects are able to persist without problems later. There was less difference between index drugs, and possession time lasted 1 to 2 months longer than persistence on a mean basis. Like persistence, possession time was lower among younger or minority individuals. Little data on persistence with OAB medication has been published in peer-reviewed journals, but research abstracts of other claims studies also report low rates of persistence. For immediate-release formulations, Juzba and colleagues19 found that nearly half (48.2%) of the patients in their 1999 claims study failed to refill their first prescription, and that continuation was more likely for patients taking tolterodine ER than oxybutynin IR (n = 436). Boccuzzi et al found 12-month persistence rates of 24% for tolterodine ER patients, and 17% for oxybutynin IR patients (n = 36 142).12 Chui et al9 and Yu et al10 reported similar 12-month results also from studies of claims data. Zhou et al reported an adjusted odds ratio of discontinuation for tolterodine ER versus oxybutynin IR users as 0.66 (P <.001; n = 11 893).8

Poor compliance can be attributed to a variety of factors, including low levels of formal education, cultural factors, side effects, and financial barriers.15,16,20 Clinical studies and patient surveys are necessary to better understand reasons for nonpersistence with OAB medications and to develop interventions to improve persistence. Clinical trials of transdermal patches for administration of oxybutynin ER have indicated reduced incidence of side effects, and studies of these new therapies in routine clinical practice are needed to replicate these findings in the real world.21,22

A good patient education program favorably impacts patient behavior, including compliance with short-term therapies, long-term management of chronic conditions, and preventive lifestyle recommendations.23 It can also build trust between healthcare providers and reduce anxiety, thus favorably impacting health outcome and patient satisfaction.24 Patient education programs have been carried out in various settings and proved to be successful in improving patient compliance.25-27 Because of its chronic nature, unpleasant side effects, and chronic treatment, a behavior-modifying education program would be of essential value to patients with OAB, particularly among those with lower educational status. Further efforts are called for to design an effective educational program specifically targeted to this population.

There are limitations to assessing persistence patterns from claims data, as done in this study. Different methods are used to measure persistency in patient populations. The most commonly used method involves obtaining information on pharmacy refill records, often from third-party institutions. These records are beneficial as an economical method for tracking compliance on large numbers of patients. However, they may overestimate compliance in that they represent prescriptions filled or refilled and not medications actually taken.

Conclusion

It can be concluded that persistence with OAB therapy in a Medicaid MCO population is low. Research is needed to understand the reasons for low persistence, so that interventions can be developed to improve persistence and compliance. Medicaid managed care plans will continue to face demands for reduced budgets and will continue to explore different approaches to optimize care and reduce risk. If low persistence with OAB therapies increases total cost of care for patients with OAB, it is critical that managed Medicaid plans understand and address this problem. Further studies are needed to understand OAB drug treatment compliance patterns in these populations as well as the factors influencing these patterns.

Figure




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