Table 2.

Odds ratios for consecutive shifts (number of shifts worked in a row) prior to the injury.

Exposure-Consecutive shifts worked in a row	Number of shifts	Cases N=502	Controls N=502	OR (95% CI)	p-value
Any shifts ≥ 4 hours (days, evenings, nights or rotating)	0	299 (59.6%)	306 (61.0%)	1*
	1–2	190 (37.8%)	190 (37.8%)	0.81 (0.60–1.08)	0.16
	3–11	13 (2.6%)	6 (1.2%)	1.19 (0.39–3.65)	0.75
12-hr(or longer) shifts (days, evenings, nights or rotating)	0	297 (59.2%)	373 (74.3%)	1*
	1–2	189 (37.6%)	124 (24.7%)	1.77 (1.30–2.44)	0.000
	3–6	16 (3.2%)	5 (1.0%)	1.30 (0.70–2.43)	0.402
12-hr (or longer) night shifts	0	336 (72.1%)	362 (77.7%)	1*
	1–2	115 (24.7%)	91 (19.5%)	1.09 (0.76–1.57)	0.64
	3–6	15 (3.2%)	13 (2.8%)	1.19 (0.71–2.01)	0.50

Note. OR = Odds Ratio; CI = confidence interval

^*Referent category