Table 3. Multivariate analysis of risk factors for OS of patients with oral cavity cancer using Cox regression (N = 1,895).

S. no	Variable	Unadjusted (95% CI)	p-value	Adjusted hazard ratio (95% CI)	p-value
1.	Age in category
	<40	1.00
	41–60  >60	1.13 (0.91–1.39)	0.24	1.27 (1.00–1.60)	0.04
		1.20 (0.91–1.57)	0.18	1.37 (1.01–1.85)	0.03
2.	Gender
	Male	1.00
	Female	0.98 (0.78–1.23)	0.89	0.90 (0.70–1.17)	0.47
3.	Education
	Illiterate	1.00
	Literate	0.84 (0.67–1.06)	0.15	0.73 (0.56–0.95)	0.02
4.	Primary site (ICD-10)
	Tongue (C02.9)	1.00
	Mouth (C04.9)	1.10 (0.79–1.52)	0.55	0.83 (0.59–1.18)	0.32
	Gum and alveolus (C03.9)	1.23 (0.94–1.61)	0.12	0.96 (0.71–1.30)	0.82
	Hard palate (C05.0)	1.28 (0.69–2.36)	0.41	0.97 (0.48–1.94)	0.93
	Buccal mucosa (06.0)	1.10 (0.89–1.36)	0.34	0.79 (0.62–1.02)	0.07
	Retromolar (06.2)	1.47 (0.89–2.42)	0.12	1.06 (0.61–1.84)	0.82
5.	Histologic grade
	Well-differentiated	1.00
	Moderately differentiated	1.42 (1.00–2.00)	0.04	1.79 (1.20–2.67)	0.004
	Poorly differentiated	2.11 (1.44–3.11)	<0.001	2.44 (1.56–3.81)	<0.001
	Undifferentiated	2.53 (1.78–3.58)	<0.001	2.01 (1.32–3.04)	0.001
6.	TNM staging
	Stage I	1.00
	Stage II	1.01 (0.64–1.58)	0.95	1.03 (0.65–1.63)	0.89
	Stage III	1.85 (1.22–2.80)	0.03	1.95 (1.27–3.01)	0.002
	Stage IV	3.09 (2.18–4.37)	<0.001	2.44 (1.65–3.61)	<0.001
7.	Intention of treatment
	Palliative	1.00
	Curative	0.17 (0.13–0.23)	<0.001	0.56 (0.37–0.85)	0.008
8.	Type of treatment
	Surgery	1.00
	Radiotherapy	1.91 (1.17–3.10)	0.009	1.63 (0.87–3.06)	0.12
	Chemotherapy	7.72 (5.87–10.1)	<0.001	3.56 (2.43–5.23)	<0.001
	Surgery + radiotherapy	0.73 (0.55–0.97)	0.033	0.63 (0.46–0.87)	0.005
	Chemo + radiotherapy	2.96 (2.01–4.36)	<0.001	2.03 (1.27–3.26)	0.003
	Surgery + chemotherapy	3.23 (1.41–7.36)	0.005	2.22 (0.88–5.57)	0.08
	Surgery + chemo + radiotherapy	1.40 (1.08–1.80)	0.009	1.03 (0.76–1.40)	0.80