Table 4.

Cox regression of the association between work status (i.e., the prevalence of working at least 25 hours a week) and number of anatomical regions with pain ≥ 3, WSP4limbs, age, annual income, and citizenship in the group below the age of 65 (n = 5780).^a,b.

Explanatory variable	Prevalence ratio (PR)	95% confidence interval
Reference categoryc	1.0	-
Number of anatomical regions with pain ≥ 3	0.88	0.81 – 0.94
WSP4limbs	0.75	0.62 – 0.92
Age
30–49	0.99	0.90 – 1.09
50–64	0.77	0.70 – 0.86
Income below median	0.62	0.57 – 0.66
Non-Nordic citizen	0.74	0.57 – 0.95

^a Acute or chronic (but not necessarily widespread, defined as number of anatomical regions with pain ≥ 3 or WSP4limbs) pain, gender, civil status, and rural residence had no significant impact on the prevalence of working at least 25 hours a week and did not act as confounders and were thus omitted from the regression model.

^b Full-time students and persons on full-time parental leave were excluded (n = 803).

^c The model-based estimate of the prevalence for the reference category, i.e., for Nordic citizens without widespread pain, defined as number of anatomical regions with pain ≥ 3 or WSP4limbs, below the age of 30, and an income above median was 96.9% (95% confidence interval 88.3% – 100%).