Co-occurrence of mental distress and insomnia associates with more severe musculoskeletal pain - Northern Finland Birth Cohort 1966 study.

Objective: This cross-sectional study demonstrates the differences in the dimensions of musculoskeletal (MSK) pain between participants with mental distress and/or insomnia among general population with MSK pain within the past 12 months.

Methods: Participants of Northern Finland Birth Cohort 1966 (NFBC1966) were studied (n = 4316). They were divided into groups based on their mental distress and insomnia status (co-occurring mental distress and insomnia [CMI], isolated mental distress [M] and insomnia [I], and absence of both [AMI]). The AMI group was used as a reference for the main analyses. The dimensions of MSK pain included frequency, bothersomeness (Numerical Rating Scale [NRS] 0-10), intensity of pain (NRS), and number of pain sites (1-8). Multinomial and general linear regression analyses were used to study the associations, and adjustments were made for sex, education, number of somatic diseases, and physical activity.

Results: The CMI group was associated with more severe pain in every dimension when contrasted to all other groups (daily pain adjusted OR 5.08, 95 % CI 3.43-7.51; bothersomeness adjusted β 1.7, 95 % CI 1.5-2.0; intensity adjusted β 1.4, 95 % CI 1.2-1.7; number of pain sites adjusted β 1.2, 95 % CI 1.0-1.4). Compared to AMI, I and M groups also had relationships with all pain dimensions, but with lower magnitude compared to the CMI group.

Conclusions: The results suggest that insomnia and mental distress co-exist with more severe MSK pain, and when co-occurring, MSK pain severity tends to increase. Therefore, contemplating insomnia and mental distress are important to consider when comprehensively evaluating MSK pain symptoms.