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Objectives: This study identifies latent classes defined by varying degrees of adherence to antipsychotic drug therapy and examines the sociodemographic, clinical, and resource utilization correlates associated with membership in each adherence class. Data and methods: Patient-level data were drawn from the 1994 to 2003, 100%-sample California Medicaid fee-for-service paid claims data for patients with schizophrenia (N = 36,195). The date of the first antipsychotic medication filled after January 1, 1999 was then used to divide each patient's data into a 6-month preindex (baseline) and a 12-month postindex (follow-up) period. Three categorical adherence indicators—a dichotomous variable of medication possession ratio greater than 0.80, the number of antipsychotic treatment attempts, and time to a change in antipsychotic medications—and two covariates—a categorical variable of duration of therapy and a dichotomous variable of polypharmacy—were used in the latent class model. Results: A three-class model returned the lowest values for all the information criteria and was therefore interpreted as follows: The prevalence rates of the latent classes were 1) 14.8% for the adherent; 2) 20.7% for the partially adherent; and 3) 64.5% for the nonadherent. Membership in the nonadherent class was associated with minority ethnicity, being female, eligibility due to welfare status, prior hospitalizations, and a higher number of prior treatment episodes. Membership in the partially adherent class was associated with higher use of outpatient care, higher rates of depot antipsychotic drug use, and polypharmacy. Conclusion: Multiple indicators of adherence to antipsychotic medication can be used to define classes of adherence that are associated with patient characteristics and distinct patterns of prior health-care use. [ABSTRACT FROM AUTHOR]

Objective: The pharmacoeconomic guidelines available in the literature or promulgated in many countries are either vague or silent about how drug costs should be established or measured so an international comparison of cost-effectiveness analysis (CEA) results can be made. The objective of this report is to provide guidance and recommendations on how drug costs should be measured for CEAs done from an internationally comparative perspective. Methods: Members of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Task Force on Good Research Practices—Use of Drug Costs for Cost Effectiveness Analysis (Drug Cost Task Force [DCTF]) subgroup from several countries were experienced developers or users of CEA models, and worked in academia, industry, and as advisors to governments. They solicited comments on drafts from a core group of 174 external reviewers and more broadly, from the members of the ISPOR at the ISPOR 12th Annual International meeting and via the ISPOR Web site. Results: Drug units should be standardized in terms of volume of active ingredient, regardless of packaging and dosing strength variations across countries. Drug costs should be measured in local currency per unit of active ingredient and should be converted to other currencies using sensitivity analyses of purchasing power parities (PPP) and exchange rates, whichever is more appropriate. When using drug prices from different years, the consumer price index for the local currency should be applied before the PPP and/or exchange rate conversion. Conclusion: CEA researchers conducting international pharmacoeconomic analysis should tailor the appropriate measure of drug costs to the international perspective, to maintain clarity and transparency on drug cost measurement in the context of international drug comparison and report the sensitivity of CEA results to reasonable cost conversions. [ABSTRACT FROM AUTHOR]

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. 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. 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 ( P = 0.03; OR 1.37; 95% CI 1.03–1.84), but had no significant effect on other OAB/UI-related comorbidities. 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. [ABSTRACT FROM AUTHOR]