Prevalence of opioid misuse in patients with cancer: a systematic review and meta-analysis

Long-term consequences of opioid consumption, such as misuse, have been a major concern in patients with chronic non-cancer pain. Potentially opioid misuse may also be a consequence in patients with cancer in opioid treatment which encouraged us to undertake this systematic review assessing the frequency of opioid misuse in this population. The search strategy comprised words related to cancer, opioid misuse, and frequency. PubMed, Embase, PsycInfo, and Cinahl were searched from inception to July 2023. Prospective studies were selected and analysed regarding frequency, study characteristics, and quality. A meta-analysis was possible to carry out for a sub-group (opioid misuse risk). From 585 abstracts screened, six articles were included. Only prevalence data were found. The prevalence of opioid misuse ranged from 5.7% to 84%, while the prevalence of opioid misuse risk varied from 2.4% to 35.4%. The pooled prevalence of opioid misuse risk was 12.3% (95% CI: 0.8–36.3; I2 = 98.4%, 95% CI: 97.2–99.1). The studies differed regarding, e.g., methods, misuse definitions, and assessment instruments. Few studies were identified and large differences in prevalence for opioid misuse and opioid misuse risk were observed. Methodological disparities and the studies quality underscore the importance of improved studies in the future.