Hard Physical Work Intensifies the Occupational Consequence of Physician-Diagnosed Back Disorder: Prospective Cohort Study with Register Follow-Up among 10,000 Workers

Table 3

The prospective associations between physician-diagnosed back disorder, physical activity at work, and risk of LTSA.

	N	%	Model 1	Model 2	Model 3	Model 4
			HR (95% CI)	HR (95% CI)	HR (95% CI)	HR (95% CI)
No back disorder, light work	5609	61.8	1.00	1.00	1.00	1.00
Back disorder, light work	928	10.2	1.57 (1.24–1.97)	1.55 (1.21–1.97)	1.48 (1.16–1.90)	1.40 (1.09–1.80)
No back disorder, hard work	2097	23.1	1.44 (1.20–1.73)	1.42 (1.17–1.73)	1.34 (1.10–1.64)	1.32 (1.08–1.62)
Back disorder, hard work	445	4.9	2.37 (1.81–3.11)	2.48 (1.87–3.29)	2.36 (1.78–3.13)	2.23 (1.68–2.96)

Model 1: adjusted for age and gender.
Model 2: model 1 + psychosocial work environment (influence at work, emotional demands, support from colleagues, and support from leader).
Model 3: model 2 + lifestyle (smoking, leisure physical activity, and BMI).
Model 4: model 3 + depression and mental health.