Table 2. Associations between daily lifting load and low-back pain intensity after the workday and in the following morning. [LSM=least squares means; CI=confidence intervals].

Lifting load (kg)		N	Minimally adjusted a			P-value	Fully adjusted b			P-value
			LSM		LSM differences		LSM		LSM differences
			Estimates		Difference (95% CI)		Estimates		Difference (95% CI)
After work
	0–499	439	2.03		Reference		2.52		Reference
	500–1999	143	2.55		0.52 (0.04–1.00) c	0.034	3.10		0.59 (0.10–1.08) c	0.019
	2000–3499	118	2.95		0.92 (0.34–1.49) c, e	0.002	3.50		0.98 (0.40–1.57) c, e	0.001
	3500–4999	191	2.91		0.88 (0.24–1.51) c	0.007	3.45		0.93 (0.28–1.58) c	0.005
	≥5000	50	3.22		1.19 (0.43–1.96) c, d	0.002	3.77		1.26 (0.48–2.03) c, d	0.002
The following morning
	0–499	439	1.20		Reference		1.59		Reference
	500–1999	143	1.64		0.43 (0.02–0.84) c	0.038	2.04		0.46 (0.04–0.87) c	0.031
	2000–3499	118	1.93		0.73 (0.23–1.22) c	0.005	2.34		0.75 (0.24–1.25) c	0.004
	3500–4999	191	1.92		0.72 (0.17–1.27) c	0.010	2.32		0.73 (0.18–1.29) c	0.010
	≥5000	50	2.11		0.91 (0.21–1.60) c	0.011	2.56		0.97 (0.27–1.67) c	0.007

^a Minimally adjusted model: Adjusted for age, sex, job title, years of employment, daily working hours, low-back pain intensity the preceding 4 weeks prior to baseline, chronic low-back pain, and perceived stress during the two weeks prior to baseline. ^b Fully adjusted model: Minimally adjusted model + BMI, leisure-time physical activity, smoking status, influence at work, access to work tools, role clarity, guidance, community and cohesion between colleagues, recognition, respectful relationship between leader and employees, and fairness. ^c Statistically significant different from 0–499 kg (reference). ^d Statistically significant different from 500–1999 kg. ^e Tendency towards a statistically significant difference from 500–1999 kg (P=0.06).