Table 7. Multivariate Cox Proportional Hazard Analysis of the Survival Factors for Cause-Specific and Overall Survival for PI-DLBCL Patients.

Variable	Number of patients	Cause-specific survival (95% CI)	P value	Overall survival (95% CI)	P value
Year of diagnosis
2000 - 2005	1,387 (36.17)	Reference		Reference
2006 - 2010	1,243 (32.41)	0.96 (0.85 - 1.08)	0.505	0.95 (0.86 - 1.05)	0.318
2011 - 2015	1,205 (31.42)	0.72(0.63 - 0.82)	< 0.001	0.79 (0.71 - 0.88)	< 0.001
Age
< 60 years	1,232 (32.13)	Reference		Reference
≥ 60 years	2,603 (67.87)	1.92 (1.69 - 2.18)	< 0.001	2.51 (2.26 - 2.78)	< 0.001
Stage
Stage 1	1,519 (39.61)	Reference		Reference
Stage 2	1,245 (32.46)	1.48 (1.30 - 1.69)	< 0.001	1.20 (1.08 - 1.32)	< 0.001
Stage 3	248 (6.47)	1.66 (1.33 - 2.07)	< 0.001	1.27 (1.06 - 1.52)	< 0.001
Stage 4	823 (21.46)	2.69 (2.35 - 3.08)	< 0.001	2.01 (1.81 - 2.24)	< 0.001
Treatment
None	355 (9.26)	Reference		Reference
Surgery	970 (25.29)	0.52 (0.44 - 0.62)	< 0.001	0.60 (0.53 - 0.69)	< 0.001
Chemotherapy	1,008 (26.28)	0.33 (0.28 - 0.39)	< 0.001	0.36 (0.31 - 0.42)	< 0.001
Chemotherapy and surgery	1,502 (39.17)	0.22 (0.19 - 0.26)	< 0.001	0.26 (0.23 - 0.30)	< 0.001

PI-DLBCL: primary intestinal diffuse large B-cell lymphoma; CI: confidence interval.