The validity of Medicaid pharmacy claims for estimating drug use among elderly nursing home residents: The Oregon experience

This study compared computerized Medicaid pharmacy claims data for nursing home residents with chart data to establish how well the claims data identified those receiving drugs within three different psychoactive drug classes (yes/no for each class) and how well the claims estimated total within-class average daily dose. Percent agreement, positive predictive value (PPV), and negative predictive value (NPV) for drug exposure were over 85% for each class. Kappas were excellent for antipsychotics and antidepressants, and good for anxiolytics. Correspondence was lower for average daily dose. Using an algorithm that credits some but not all doses associated with overlapping claims, correlations ranged from 0.97 to 0.66. Agreement on therapeutic dose was excellent for antipsychotics (κ = 0.81) and fair to good for antidepressants and anxiolytics (κ = 0.63, and κ = 0.52, respectively). The findings suggest that Medicaid pharmacy claims data are reasonably accurate for quality assurance and accreditation purposes.