Using aggregate data on dispensed drugs to evaluate the quality of prescribing in urban primary health care in Sweden

Abstract

Valuable evaluations of the quality of drug prescribing in routine health care are difficult to perform. It is even more difficult to study prescribing in a non-gatekeeping healthcare system with a variety of caregivers involved in patient care. Consequently, there is a need to develop methods for evaluation using data available in routine health care. The aim of this study was to analyse possibilities and limitations for evaluation of the quality of drug prescribing using routinely collected aggregate data on dispensed drugs and health care provision. A secondary aim was to study the effects of allocating more resources to primary health care (PHC) on the quality of drug prescribing. The study was performed with routinely collected data from 10 PHC centres in Stockholm, Sweden that were participating in an intervention project that aimed to decrease the number of inhabitants per PHC doctor. Time periods for analysis were October-December 1999, 2000 and 2001. Data on dispensed prescriptions were analysed by age using Anatomical Therapeutic Chemical (ATC) classification/defined daily dose (DDD) methodology. The general quality of prescribing was determined using DU90% methodology (identifying the number of drugs constituting 90% of the volume expressed in DDDs and the adherence to evidence-based recommendations) and ratios between different treatment alternatives. The total volume and cost of drugs prescribed to the population was also analysed. In 2001, PHC centres accounted for, on average, 27% (range 14-36%) of all doctor consultations and 32% (range 22-43%) of all prescriptions to populations in the corresponding primary care districts. There was great variation between the different PHC centres with regard to the prescribing doctors' compliance with guidelines from the regional drug and therapeutics committee, and the utilization of health care and drugs among the population in the corresponding primary care districts. No clear improvement was observed over time. Analysis of aggregated prescription and healthcare data at population level was feasible. However, the effects of allocation of increasing resources to PHC on the quality of drug prescribing need to be analysed in a broader context.