Effects of 'doctor shopping' behaviour on prescription of addictive drugs in Sweden

Free choice of health care providers is aimed to improve the quality of health care by increasing both access to it and the competition between providers. However, it may also give patients possibilities for doctor shopping (DS) behaviour, i.e., visiting different providers to receive illicit drug prescriptions. Abuse of prescribed addictive drugs is a growing problem worldwide and is associated with increased mortality, lower quality of life and other problems on both the individual and societal level. We study DS behaviour for three categories of addictive drugs - opioid painkillers, benzodiazepine anxiolytics, and z-hypnotic sleeping drugs, in the outpatient care sector in Vadsterbotten County, Sweden. Our dataset contains all drug prescriptions purchased by the residents of Vadsterbotten in the period from January 2014 to April 2016 (approximately 160,000 observations). To identify signs of addictive prescription drugs abuse by DS, we analyse overlapping prescriptions. We use 'Defined Daily Doses' (DDDs), which is the average treatment dose of a specific drug per day for adults, as a proxy for the treatment duration. To control for medically legitimate overlaps, we compare overlapping prescriptions within a clinic with overlapping prescriptions between different clinics. Our empirical results suggest that there is a significant and positive relationship between the number of overlapping doses and the number of unique providers in the overlap. More specifically, we find that visiting different providers on average gives patients up to three additional DDDs per day. This is three times higher than the standard treatment dose. We discuss policy implications in the concluding discussion.