ABSTRACT
OBJECTIVE: We sought to evaluate several statistical modeling approaches in predicting prospective total annual health costs (medical plus pharmacy) of health plan participants using Pharmacy Health Dimensions (PHD), a pharmacy claims-based risk index. METHODS: We undertook a 2-year (baseline year/follow-up year) longitudinal analysis of integrated medical and pharmacy claims. Included were plan participants younger than 65 years of age with continuous medical and pharmacy coverage (n = 344,832). PHD drug categories, age, gender, and pharmacy costs were derived across the baseline year. Annual total health costs were calculated for each plan participant in follow-up year. Models examined included ordinary least squares (OLS) regression, log-transformed OLS regression with smearing estimator, and 3 two-part models using OLS regression, log-OLS regression with smearing estimator, and generalized linear modeling (GLM), respectively. A 10% random sample was withheld for model validation, which was assessed via adjusted r, mean absolute prediction error, specificity, and positive predictive value. RESULTS: Most PHD drug categories were significant independent predictors of total costs. Among models tested, the OLS model had the lowest mean absolute prediction error and highest adjusted r. The log-OLS and 2-part log-OLS models did not predict costs accurately as the result of issues of log-scale heteroscedasticity. The 2-part model using GLM had lower adjusted r but similar performance in other assessment measures compared with the OLS or 2-part OLS models. CONCLUSION: The PHD system derived solely from pharmacy claims data can be used to predict future total health costs. Using PHD with a simple OLS model may provide similar predictive accuracy in comparison to more advanced econometric models.
Subject(s)
Drug Costs , Drug Prescriptions/economics , Health Care Costs , Models, Econometric , Adolescent , Adult , Child , Child, Preschool , Clinical Pharmacy Information Systems , Female , Forecasting , Health Expenditures , Health Maintenance Organizations/economics , Humans , Infant , Infant, Newborn , Insurance Claim Review , Longitudinal Studies , Male , Middle Aged , Preferred Provider Organizations/economics , United StatesABSTRACT
BACKGROUND: Persistency with drug therapy reflects a number of factors, including patient tolerability of adverse events resulting from therapy and clinician satisfaction with the medication's effectiveness in reducing intraocular pressure. OBJECTIVE: This study assesses persistency with topical glaucoma medications administered as initial therapy by evaluating rates of discontinuation and change in therapy. METHODS: A retrospective cohort study was conducted using pharmacy claims data from 3 geographically diverse healthcare plans. Newly treated glaucoma patients younger than 65 years of age were selected based on an initial glaucoma medication fill during a 12-month period. Patients were followed for persistency, defined as discontinuation or change (switch or add-on) of initial glaucoma therapy; discontinuation of therapy was also evaluated as a separate end point. RESULTS: In all, 1330 patients (followed for 1126 person-years) met the eligibility criteria. Compared with latanoprost users, patients initiated on other topical monotherapies were more likely to discontinue or change therapy, and patients initiated on other topical monotherapies were more likely than latanoprost users to discontinue therapy. CONCLUSION: Population-based data indicate that latanoprost offers superior persistency compared to agents from other popular classes of topical ocular hypotensives.
