Assessing adherence-based quality measures in epilepsy.

OBJECTIVE To examine the relationship of three alternative measures of adherence with seven negative outcomes associated with epilepsy for development of a quality measure in epilepsy. DESIGN Retrospective cohort analysis. SETTING PharMetrics national claims database. PARTICIPANTS Patients in the PharMetrics database for the years 2004-08 taking antiepileptic drugs. INTERVENTION None. MAIN OUTCOME MEASURES For each definition of adherence, the odds ratios (ORs) comparing non-adherent with adherent groups were assessed for consistency and direction for the number of hospital admissions, emergency room (ER) visits, head injuries including traumatic brain injuries, falls, motor vehicle accidents (MVAs), fractures and a 'seizure' outcome defined as hospital admissions or ER visits with a primary diagnosis of epilepsy or convulsions. RESULTS The inclusion criteria were met by 31 635 individuals. In the multivariate analysis, the adherent group had lower odds of hospital admissions with ORs for the eight specifications ranging from 0.729 to 0.872 and ER visits where ORs for the eight specifications ranged from 0.750 to 0.893. The eight ORs for head injuries ranged from 0.647 to 0.888. For fractures, the ORs ranged from 0.407 to 0.841. Our proxy for seizure was inconsistently associated with adherence status. CONCLUSIONS All the adherence measures defined non-adherent groups that were associated with negative outcomes in epilepsy.