To Örebro University

Increases in opioid overdoses and related public health harms, particularly in North America, have led to great concerns about opioid pharmacotherapies for pain. However, the extent of the contribution of prescribed opioid analgesic use, as opposed to illicit opioid use or medication diversion, to the etiology of substance abuse among young people remains uncertain. This study used a co-twin-control design in data from a linkage of nationwide Swedish registers to examine risk of substance abuse. We identified a birth cohort of Swedish adolescents and young adults who were naïve to prescription opioid analgesics (aged 13–29 years; N = 1,541,862). Between 2007 and 2013, approximately 13% of these individuals initiated prescription opioid analgesic receipt (n = 193,922). Relative to non-recipients matched 1:1 on demographics, prescription opioid analgesic recipients had greater rates of subsequent substance abuse, as indexed by registered diagnoses, medication treatments, causes of death, and convictions for drug-or-alcohol-related crimes (HR, 2.29; 95% CI 2.21–2.36). This association was somewhat attenuated but persisted in comparisons of co-twins and other multiple births (HR, 1.47, 95% CI 1.15–1.87). That is, a family-based comparison could not rule out at least some causal role for prescription opioid analgesic receipt in risk of substance abuse among young people. Further research is needed to determine the extent to which within-family confounding explains the remaining association.