Chronic MSK pain and its association with all-cause mortality: a study of 194,419 participants in UK Biobank.

Problem

Musculoskeletal (MSK) pain is pain affecting the bones, ligaments, tendons or muscles. MSK pain may be localised to one site, multiple sites, or be widespread throughout the body, and may present as acute or chronic symptoms. Despite its prevalence and severity, no study has to date examined mortality outcomes associated with chronic MSK pain, nor factors which may mediate its severity. Further, no study has quantified the differing outcomes in patients with single site, multisite or chronic pain all over the body. This study addresses this gap.

Approach

We used prospective cohort data from the UK Biobank (N=502,543) to examine chronic MSK pain. Participants with chronic MSK pain affirmatively responded to experiencing pain in at least one MSK site (neck/shoulder, back, hip, knee or pain all over the body) lasting for a period of >3 months. We examined demographic factors –age, sex, and socioeconomic status – and lifestyle factors – smoking status, frequency of alcohol intake, body mass index (BMI) and physical activity level – for patients with no, single site, multisite or pain all over the body. Using a list of 43 prevalent long-term conditions (LTCs), we investigated the effect of LTCs on each chronic MSK pain group.Proportion of deaths in each subgroup of chronic MSK pain was examined using Kaplan-Meier graphs. All-cause mortality was measured using a fully adjusted Cox’s proportional hazards model controlling for age, sex, socioeconomic status (by Townsend score), smoking status, frequency of alcohol intake, BMI, physical activity and number of LTCs.

Findings

194,419 (38.6%) participants reported chronic MSK pain in at least 1 site. 1.4% (N=7129) participants reported chronic pain all over the body. During the follow up period (median = 7 years), 6.1% of patients with chronic pain all over the body had died, compared with 2.6% of patients with no chronic MSK pain.When controlling for demographic factors, lifestyle factors and number of LTCs as described above, there was no significantly increased association between single site (hazard ratio (HR) 0.94, 95% confidence interval (CI) 0.90 – 0.98) nor multisite (HR 0.99 95% CI 0.94 – 1.04) chronic MSK pain and all-cause mortality. However, there remained a significant association between chronic pain all over the body and death, with an 18% greater risk of all-cause mortality reported for these participants (HR 1.18 95% CI 1.06 – 1.32).

Consequences

Whilst all-cause mortality is not positively mediated by multisite MSK pain, chronic pain all over the body is shown to be a significant factor in patient’s outcomes. This has strong implications for the urgency of examination and treatment of this subset of chronic pain patients across all levels of the healthcare system.