Risk factors for neck pain among forklift truck operators: a retrospective cohort study

Table 3 Incidence rate ratios for neck pain by years of exposure adjusted for age and gender, psychosocial aspects and hand/shoulder work

	A = age and gendSer		B = A+ Psychosocial aspects		C = A+ Hand/shoulder work
Neck postures and exposure time	IRR^a	95% CI^b	IRR	95% CI	IRR	95% CI
Extension
Non exposed	Reference level		Reference level		Reference level
1–2 years	3.09	1.08–8.86	1.23	0.97–8.85	2.09	0.70–6.28
3–4 years	5.34	2.42–11.78	4.63	2.00–10.72	3.56	1.52–8.36
5–9 years	2.01	1.00–4.03	1.89	0.91–3.92	1.38	0.63–2.99
10- years	1.04	0.48–2.20	1.05	0.48–2.31	0.71	0.32–1.60
Rotation
Non exposed	Reference level		Reference level		Reference level
1–2 years	7.10	2.63–19.14	5.86	2.08–16.50	6.24	1.97–19.79
3–4 years	5.70	2.47–13.27	5.00	2.09–11.99	4.76	1.67–13.65
5–9 years	1.70	0.78–3.74	1.49	0.67–3.31	1.58	0.62–4.04
10- years	1.24	0.53–2.91	1.13	0.47–2.71	1.11	0.39–3.14
Lateral flexion
Non exposed	Reference level		Reference level		Reference level
1–2 years	5.60	2.23–14.09	4.51	1.67–12.13	4.35	1.68–11.29
3–4 years	3.76	1.80–7.80	3.54	1.67–7.49	3.06	1.40–6.69
5–9 years	1.55	0.79–3.05	1.37	0.68–2.77	1.30	0.64–2.66
10- years	0.90	0.41–1.94	0.84	0.37–1.89	0.72	0.31–1.64

Bold numbers are those statistically significant at 95% confidence level
Poisson multivariate regression model. Person years were calculated from years of employment and years of exposure up to the debut of perceived neck pain
^aIncidence rate ratio
^b95% Confidence interval. Column B; Psychosocial factors included: mental stress, lack of co-worker support and freedom to perform your work. Column C; Hand/shoulder work includes monotonous work with arms/hands, heavy lifting and work involving hands above shoulder level

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