Purpose: Over 25 million Americans reported having daily pain and between 5 and 8 million Americans used opioids to treat chronic pain in 2012. This is the first systematic review with meta-analysis to determine the effects of long-term opioid use on the Physical Component Summary (PCS) score and Mental Component Summary (MCS) scores of a Health-Related Quality of Life instrument in adults without opioid use disorder.
Methods: The a priori eligibility criteria for the PubMed (MEDLINE), Scopus, and PsyINFO searches were (1) randomized controlled trial, (2) at least one opioid intervention group, (3) minimum of 4-week duration of opioid use, (4) comparative control group, and (5) adults ≥18 years that do not have dominant disease. The unit of analysis was the standardized mean difference effect size (Hedges's g). All results were pooled using random-effects models.
Results: Of the 340 non-duplicate citations screened, 19 articles comprising 26 treatment comparisons and 6168 individuals (treatment n = 3160; comparators n = 3008 with duplicates removed) met the inclusion criteria for the systematic review. Thirteen treatment comparisons were available for the meta-analysis. Across all PCS analyses, small, statistically significant improvements were observed (opioid versus opioid only: g = 0.27, 95% CI 0.05-0.50, opioid versus placebo only: g = 0.18, 95% CI 0.08-0.28, and all studies combined: g = 0.22, 95% CI 0.11-0.32). There were small but not statistically significant changes on the MCS scores. Overall, high heterogeneity was present.
Conclusions: PCS scores improve with no change in MCS scores. However, long-term opioid trials are rare and only two trials included lasted longer than 1 year.
Keywords: Health-related quality of life; Meta-analysis; Opioid; Randomized controlled trials; Systematic review.