Lower copay and oral administration: predictors of first-fill adherence to new asthma prescriptions.

BACKGROUND: Nonadherence to asthma medications is associated with increased emergency department visits and hospitalizations. If adherence is to be improved, first-fill adherence is the first goal to meet after the physician and patient have decided to begin treatment. Little is known about first-fill adherence with asthma medications and the factors for no-fill.

OBJECTIVE: The goal of the study was to examine the proportion of patients who fill a new prescription for an asthma medication and analyze characteristics associated with this first-fill.

METHODS: This retrospective cohort study linked electronic health records with pharmacy claims. The cohort was comprised of 2023 patients aged 18 years or older who sought care from the Geisinger Clinic, had Geisinger Health Plan pharmacy benefits, and were prescribed an asthma medication for the first time between 2002 and 2006. The primary outcome of interest was first-time prescription filled by the patient within 30 days of the prescription order date. Covariates examined included factors related to the patient (ie, age, sex, and ethnicity), comorbidities and utilization (ie, Charlson comorbidity index, number of office visits, number of additional medications), asthma treatment (ie, delivery route, pharmacologic class), and pharmacy copay amount. A logistic-regression model was used to determine covariates associated with first-fill.

RESULTS: The overall first-fill rate for new asthma medications was 78%. First-fill rate was lower for patients with a copay above the mean of $12 (odds ratio = 0.76; 95% confidence interval, 0.58-0.99) and higher for patients prescribed oral plus inhaled medications (versus inhaled only, odds ratio = 3.91; 95% confidence interval, 2.15-7.11).

CONCLUSIONS: SEVERAL FACTORS ASSOCIATED WITH FAILING TO FILL AN INITIAL PRESCRIPTION FOR ASTHMA CAN BE ADDRESSED THROUGH SIMPLE INTERVENTIONS: screening for difficulties a patient may have in filling prescriptions, avoiding nonformulary medications, and recognizing the barrier that high copays present. In addition, for employers and policymakers, decreasing copay may improve adherence and, therefore, asthma control.