The impact of childhood emotional abuse on pain interference among people with chronic pain who inject drugs in Vancouver, Canada

Objective. High levels of chronic pain interference with daily activities are known to negatively impact quality of life. Although mental health conditions have been associated with pain interference and child abuse, research has been mixed regarding it acting as a mediator, with even less known among people who inject drugs. Therefore, we sought to explore childhood emotional abuse and pain interference among this population. Methods. Data were derived from two prospective cohort studies of community-recruited people who inject drugs in Vancouver, Canada, between June 2014 and November 2016. We employed multivariable generalized estimating equations to examine the relationship between childhood emotional abuse and pain interference in the past six months. We also conducted a mediation analysis to examine whether mental health disorder diagnoses mediated this association. Results. Among 822 eligible participants, 341 (41.5%) reported childhood emotional abuse. In a multivariable analysis, experiencing childhood emotional abuse remained independently associated with pain interference (adjusted odds ratio = 1.33, 95% confidence interval [CI] = 1.05-1.70) after adjusting for a range of confounders. Results from the mediation analysis yielded a statistically significant positive average causal mediation effect (b=0.01, 95% CI = 0.001-0.02). Approximately 12% of the effect was due to mediation. Conclusions. Our results demonstrate among people who inject drugs with chronic pain, those who experienced childhood emotional abuse were more likely to report pain interference, which was partially mediated by mental health disorder diagnosis history. These findings highlight the importance of incorporating screening and appropriate treatment for mental illness into chronic pain treatment.