Sex Differences in the Prevalence of Chronic Pain in Mid-Life: A Systematic Review and Meta-Analysis.

Background/Objectives: Chronic pain (CP) affects more females than males, but it is unclear how differences present at mid-life, a period characterized by distinct changes which may exacerbate inequality. Methods: Using a search strategy combining MeSH terms and Boolean operators, we searched MEDLINE, EMBASE, AMED, and PSYCHinfo for population-representative cohort or cross-sectional studies of CP prevalence. We conducted a systematic review of CP prevalence by sex and the difference in prevalence of CP between sexes at mid-life through narrative synthesis and random-effects meta-analysis. A sensitivity analysis assessed how sex differences varied by pain type, pain definition, and geographic region. Results: Eighteen eligible articles provided information on CP prevalence by sex and demonstrated variation according to pain type. All but three studies found a higher prevalence of CP in females than males. Based on a random-effects meta-analysis of eight studies, the overall relative risk (RR) was 1.16 (95% CI: 1.11-1.21) for females compared with males, with no evidence of heterogeneity. However, in subgroup analyses, the RR was lower for generic CP (RR = 1.16, 95% CI: 1.11-1.21) than for fibromyalgia (RR = 3.13, 95% CI: 1.22-8.04). Conclusions: Our review found that females are more likely to experience CP at mid-life, although the RR was small. Larger sex differences may be observed for fibromyalgia, but the small sample sizes highlight the need for larger studies to provide more precise estimates of different types of pain.