Correlation between symptoms and functioning in psychiatric patients and temporal patterns of medication refills derived from pharmacy prescription claims

Objectives: Pharmacy dispensing claims data provide longitudinal records of prescriptions and refill events. Previous studies in psychiatric patients have utilised these data to derive indicators of medication adherence based on information regarding the amount of medication supplied and its dosage. An alternative approach was developed in which the regularity of medication refill events was analysed as a potential indicator of psychiatric patient symptoms and functioning. Methods: A method to quantify the regularity of medication refills was developed and subsequently used to investigate how the resulting regularity index (RI), derived from retrospective prescription refill records, correlated with symptomatic and functional assessments of 89 psychiatric patients after adjusting for covariates. Results: A two-step hierarchical regression model indicated that variances explained by prior hospitalisation and the RI were significant for patient scores on the Kessler 10 Psychological Distress Scale (K10), standard beta value 0.22, p < 0.05, for the SF-12 MC, standard beta value −0.31, p < 0.01, and the Work and Social Adjustment Scale (WSAS), standard beta value 0.31, p < 0.01. Conclusions: This method to quantify the regularity of medication refills using prescription supply date alone may provide valuable information about patients’ symptoms and functioning.