Persons with chronic widespread pain experience excess mortality: longitudinal results from UK Biobank and meta-analysis

Cause-specific mortality of patients with severe chronic pain referred to a multidisciplinary pain clinic: a cohort register-linkage study

Background and aims

Almost 20% of the adult population suffers from chronic pain. Chronic pain may be linked to an elevated mortality; however, results from previous studies are inconsistent. Some studies find similar mortality levels in chronic pain patients and pain-free controls while other studies show elevated mortality levels among chronic pain patients, primarily with respect to cancer, diseases of the circulatory and respiratory systems, and suicide. These conflicting results are potentially due to different population samples and different operational definitions of chronic pain. Further research on overall and cause-specific mortality in patients with severe chronic pain is needed to inform clinical practice. The objective of this register-linkage study was to investigate whether patients with severe chronic pain referred to multidisciplinary pain treatment have higher cause-specific mortality rates than the general population.

Methods

In this register-linkage cohort study, data from 6,142 chronic pain patients (female: n=3,941, male: n=2,201, mean age: 48.2±14.2; range: 16–97 years) attending an interdisciplinary Pain Center in Odense, Denmark from 2005 to 2014 were linked to the Danish Register of Causes of Death. Age and gender standardized mortality ratios (SMRs) with their 95% confidence intervals (CI) were calculated and compared with those of the general population. Data from the general population was extracted from the Danish Register of Causes of Death, and Causes of death were classified according to national Classification of Disease (ICD-10).

Results

In all, 276 deaths (women: n=152, men: n=124) were observed among the chronic pain patients, and a six-fold higher overall mortality rate was found [SMR: 6.2 (95% CI: 5.5–7.0)] compared with the general population. Elevated cause-specific mortality rates were noted for chronic patients with respect to cancer and neoplasms [4.7 (95% CI: 3.7–5.9)], diseases of the circulatory system [5.7 (95% CI: 4.3–7.3)], diseases of the respiratory system [8.7 (95% CI: 6.2–11.9)], and suicide [7.3 (95% CI: 2.7–15.9)].

Conclusions

The overall mortality rate of patients with severe chronic pain in this study was six-fold higher than the rate of the general population in this region. This was reflected in select specific causes of death (cancer and neoplasms, diseases of the circulatory system, diseases of the respiratory system, and suicide). The results are in agreement with previous studies and emphasize the need to understand which factors causally affect this increased mortality allowing for targeted interventions in similar chronic pain populations.

Implications

Potential reasons for the excess mortality should be adequately addressed by future studies in order to better target this in the management of these patients. The chronic pain population included in this study may have several comorbidities contributing to the increased mortality. To better address these aspects, complete medical profiles are needed in future studies. In addition, implementation of management strategies towards potential risk factors such as poor diet, low levels of physical activity, smoking, and high BMI as well as sleep deprivation and morphine use previously shown associated with having pain may reduce the excess mortality ratio.

Parental chronic widespread pain and the association with chronic widespread pain in adult offspring: Family-linkage data from the Norwegian HUNT Study

BACKGROUND

Individuals experiencing chronic widespread pain (CWP) have greater disability and poorer quality of life compared to those with other chronic painful conditions; although research identifying risk factors for CWP is lacking. We aimed to investigate whether parental CWP increases the risk of offspring CWP, and if offspring body mass index (BMI) and leisure time physical activity modify this association.

METHODS

We included 6589 parent-offspring trios participating in the Norwegian HUNT Study in 1995-1997 and 2006-2008. Logistic regression was used to calculate adjusted odd ratios (ORs) (95% confidence intervals, CIs) as estimates of relative risk for offspring CWP. We analysed the joint effect of parental CWP and offspring BMI or leisure time physical activity on offspring risk of CWP and calculated the relative excess risk due to interaction (RERI).

RESULTS

In total, 886 (13.5%) offspring developed CWP during follow-up. Having one (OR = 1.23, 95% CI, 1.05-1.44) or both parents with CWP (OR = 1.89, 95% CI, 1.50-2.38) increased the risk of offspring CWP. In analyses of joint effects, ORs were 1.84 (95% CI, 1.31-2.56) and 3.35 (95% CI, 1.94-5.77) in normal weight and obese offspring, respectively, when both parents had CWP. The estimate of RERI suggested some synergistic effect (RERI = 1.19, 95% CI, -0.68 to 3.05), although precision was low. Risk of CWP was similar in active (OR = 2.05, 95% CI, 1.56-2.70) and inactive (OR = 1.96, 95% CI, 1.31-2.91) offspring when both parents had CWP.

CONCLUSION

Parental CWP increases the risk of CWP in adult offspring, particularly if both parents have CWP and offspring are obese. This highlights a familial predisposition for CWP and an important target group for preventive measures.

SIGNIFICANCE

The parent-offspring transmission of CWP is stronger in obese offspring (particularly when both parents have CWP). This study is the first to investigate the interaction between modifiable lifestyle factors, familial factors and CWP.