Mortality rate and causes of death in women with self-reported musculoskeletal pain: Results from a 17-year follow-up study
Authors: Nitter Anne K. , Forseth Karin Ø. 
Published: April 2013

Aabstract

Introduction
Chronic musculoskeletal pain represents a significant health problem among adults in Norway. The prevalence of chronic pain is reported to be 35-53% in cross sectional studies of both genders. For many years, it has been a common opinion among medical doctors that chronic pain may indeed reduce a person’s quality of life, but not affect life expectancy. However, over the previous two decades, reports about mortality and cause of death in individuals with chronic pain have been published. So far, several studies conclude that there is an increased mortality in patients with chronic pain, but it is not clear what causes this. Increased occurrences of cardio-vascular death or cancer death have been reported in some studies, but not verified in other studies.

Aims of the study
The aims of this study were to estimate the mortality rate in females with different extent of pain, to identify potential risk factors for death and to investigate if the causes of death differ according to prior reported pain.

Methods
This is a prospective population-based study of all women between 20 and 50 years registered in Arendal, Norway, in 1989 (N = 2498 individuals). At follow-up in 2007, 2261 living females were retraced, 89 had died.
All subjects received a questionnaire containing questions about chronic pain (pain ≥ 3 months duration in muscles, joints, back or the whole body) as well as 13 sub-questions about pain-modulating factors, non-specific health complaints and sleep problems, by mail in 1990, 1995 and 2007. Only subjects who answered the questionnaire in 1990 were included in the analyses. Of the deceased, 71 had answered the questionnaire in 1990.
A multivariate model for cox regression analysis was used in order to clarify if chronic pain, sleep problems, feeling anxious, frightened or nervous and number of unspecific health were risk factors for death.
The causes of death of 87 of the deceased individuals were obtained by linking the ID-number with the Norwegian Cause of Death Registry.

Results
The ratio of deceased responders was 2% (14/870) among those with no pain versus 5% (57/1168) among those with chronic pain at baseline. When separating into chronic regional pain and chronic widespread pain, the mortality rate was respectively 4% and 8% in the different groups. Age adjusted hazard ratio for mortality rate in individuals with initially chronic pain was [HR 2.5 (CI 1.4–4.5)] compared to pain free individuals. In the multivariate analysis, having chronic pain [HR 2.1 (1.1–4.2)] and feeling anxious, frightened or nervous [HR 3.2 (1.8–5.6)] were associated with increased risk of death. There was no difference in death from cardiovascular disease or malignancies between the groups of pain free individuals vs. the group of individuals with chronic pain.

Conclusion
The mortality rate was significantly higher for individuals with chronic pain compared to pain free individuals, adjusted for age. In addition, feeling anxious, frightened or nervous were risk factors for death. There was an increase in all-cause mortality.