Title:
The sex-specific interrelationship between spinal pain and psychological distress across time in the general population. Results from the Stockholm Public Health Study.

Abstract:
Detailed knowledge about the interrelationship between neck pain, back pain, and psychological distress is important from a public health prospective, but missing because of lack of large population-based cohort studies.
To assess and compare the sex-specific recovery rate of spinal pain and psychological distress as single and comorbid conditions, to describe the interrelationship between these conditions at the baseline (2002) and follow-up 5 years later, and to explore the questions of spinal pain as a risk factor for the onset of psychological distress and vice versa.
A prospective cohort study.
General population in Stockholm county aged 18 to 84 years, n=19,774.
Spinal pain (modified Nordic Pain Questionnaire) and psychological distress (General Health Questionnaire-12).
A random sample of the population in Stockholm was approached with postal questionnaires at the baseline and at follow-up.
Comorbidity of spinal pain and distress was twice as common among women (11%) than among men (4%) (relative risk=2.4, 95% confidence interval [CI]: 2.1-2.7). Women also more commonly had spinal pain without psychological distress (women, 20%; men, 14%) and vice versa (women, 15%; men, 12%). Comorbidity makes recovery less probable (women, 26%; men, 27%) than having single conditions of spinal pain (women, 41%; men, 44%) or psychological distress (women, 49%; men, 52%). No statistical significant sex differences were seen. Twenty-four percent of the women and 17% of the men with spinal pain without psychological distress at the baseline had psychological distress at follow-up. Corresponding figures for spinal pain among participants with psychological distress without spinal pain at the baseline were 24% and 20%. Spinal pain was a determinant of psychological distress (odds ratio [OR]=2.6, 95% CI: 2.3-2.9) and vice versa (OR=2.0, 95% CI: 1.8-2.2).
Spinal pain and psychological distress as comorbid and single conditions are common in the general population, especially among women. Comorbidity affects recovery negatively both in men and women. This study confirms the bidirectional association between spinal pain and psychological distress in the general population.