Association between dysmenorrhea and chronic pain: a systematic review and meta-analysis of population-based studies

OBJECTIVE: The objective of the study was to synthesize the epidemiological findings for the associations between dysmenorrhea, including primary dysmenorrhea and endometriosis-associated dysmenorrhea and any chronic pain conditions, including chronic pelvic pain, and chronic nonpelvic pain. DATA SOURCES: The data sources included PubMed, Embase, and CINAHL from inception to December 2019. STUDY ELIGIBILITY CRITERIA: The study criteria included observational population-based studies in which the relationship between dysmenorrhea and the presence or severity of chronic pain was examined. STUDY APPRAISAL AND SYNTHESIS METHODS: Each study was double coded and evaluated for bias based on the modified Newcastle and Ottawa Scale. Random-effect meta-analyses were conducted to quantify the associations between dysmenorrhea and the presence of chronic pelvic and nonpelvic pain. RESULTS: Out of 9452 records, 32 studies were included, with 14 reporting associations between dysmenorrhea and chronic pelvic pain, and 20 for dysmenorrhea and chronic nonpelvic pain. Primary dysmenorrhea and endometriosis-associated dysmenorrhea were examined in 7 studies, respectively. More than 30% of the studies were categorized as poor quality, 56% as moderate, and 12.5% as high. Dysmenorrhea was positively associated with both the presence and severity of chronic pelvic and nonpelvic pain conditions. Based on 6689 women from 8 studies, those with chronic pelvic pain had 2.43 (95% confidence interval, 1.98-2.99, I2, 42%) times the odds of having dysmenorrhea compared with those without. Based on 3750 women from 11 studies, those with chronic nonpelvic pain had 2.62 (95% confidence interval, 1.84-3.72, I2, 72%) times the odds of having dysmenorrhea compared with those without. Overall, dysmenorrhea was associated with 2.50 (95% confidence interval, 2.02-3.10) times the odds of chronic pain, which did not differ by chronic pelvic vs chronic nonpelvic pain, community vs clinical populations, or different geographical regions. CONCLUSIONS: Dysmenorrhea may be a general risk factor for chronic pain, although whether primary dysmenorrhea increases the risk for chronic pain is unclear. Given that adolescence is a sensitive period for neurodevelopment, elucidating the role of primary dysmenorrhea in pain chronicity in future longitudinal studies is important for preventing both chronic pelvic and nonpelvic pain.