Table 2.

Multiple Cox proportional hazard regression for estimation of adjusted hazard ratios on head and neck cancer.

Variable	Model for peptic ulcer		Model for eradication
	Overall period	≥ 6 years	Overall period	≥ 6 years
Study group (ref: control)
Peptic ulcer	1.09(0.96–1.22)	1.24(1.01–1.51)
Peptic ulcer without eradication			1.23(1.08–1.40)	1.44(1.16–1.80)
Peptic ulcer with eradication			0.90(0.76–1.05)	1.01(0.78–1.31)
Sex (ref: female)
Male	4.85(4.14–5.68)	5.08(3.9–6.61)	4.89(4.17–5.73)	5.06(3.90–6.57)
Age (ref: 30–45)
< 30	0.22(0.15–0.33)	0.21(0.12–0.38)	0.22(0.14–0.32)	0.20(0.11–0.37)
45–65	1.58(1.35–1.84)	1.12(0.89–1.42)	1.58(1.36–1.84)	1.15(0.91–1.45)
≥ 65	1.30(1.07–1.58)	1.11(0.81–1.52)	1.28(1.06–1.56)	1.06(0.78–1.46)
Urbanization (ref: Urban)
Sub-urban	1.17(1.02–1.33)	1.19(0.95–1.48)	1.16(1.02–1.33)	1.17(0.94–1.46)
Rural	1.39(1.17–1.66)	1.39(1.03–1.87)	1.38(1.15–1.65)	1.36(1.01–1.83)
Length of hospital staysa (ref: 0 day)
1–6 days	1.24(1.05–1.47)	1.10(0.82–1.48)	1.24(1.04–1.46)	1.08(0.81–1.45)
≥ 7 days	1.57(1.32–1.86)	1.50(1.11–2.03)	1.53(1.29–1.81)	1.52(1.13–2.04)
Baseline co-morbidity
Hypertension	1.06(0.92–1.22)	1.06(0.83–1.36)	1.05(0.91–1.21)	1.09(0.86–1.40)
Diabetes mellitus	1.08(0.91–1.28)	1.04(0.76–1.41)	1.08(0.91–1.27)	0.99(0.73–1.34)
Asthma	0.94(0.73–1.20)	1.00(0.65–1.52)	0.93(0.73–1.20)	1.04(0.69–1.56)
COPD	1.01(0.85–1.20)	0.90(0.67–1.21)	1.01(0.85–1.19)	0.92(0.69–1.23)
Chronic kidney disease	1.06(0.69–1.62)	0.38(0.09–1.52)	1.04(0.68–1.60)	0.36(0.09–1.44)
Chronic liver diseases	1.39(1.22–1.58)	1.27(1.01–1.59)	1.38(1.21–1.58)	1.29(1.04–1.62)

COPD, chronic obstructive pulmonary disease.

^aLength of hospital stays, was the sum of the days in the hospitalization within 2 years before index date.