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Table 3 Imbalances of baseline characteristics between right- and left-sided colon cancer patients

From: Better survival in right-sided versus left-sided stage I - III colon cancer patients

  

Logistic regression in raw data (N = 91,4166)a

Patient characteristics after stratified bipartite propensity score matching (N = 90,067)c

  

OR (95 % CI)

Pb

Total

Right-sided carcinoma

Left-sided carcinoma

Pb

N = 90,067

N = 51,331

N = 38,736

Tumor stage

Stage I

D)

 

24,924 (27.7 %)

13,622 (26.5 %)

11,302 (29.2 %)

E)

(AJCC 6th ed.)

Stage II

  

33,002 (36.6 %)

19,790 (38.6 %)

13,212 (34.1 %)

 
 

Stage III

  

32,141 (35.7 %)

17,919 (34.9 %)

14,222 (36.7 %)

 

T-stage

T1

Reference

<0.001

11387.4 (12.6 %)

6378 (12.4 %)

5009.4 (12.9 %)

0.908

 

T2

1.45 (1.36–1.55)

 

17213.6 (19.1 %)

9360 (18.2 %)

7853.6 (20.3 %)

 
 

T3

1.15 (1.08–1.22)

 

50984.6 (56.6 %)

29,704 (57.9 %)

21280.6 (54.9 %)

 
 

T4

1.08 (1.00–1.17)

 

10481.4 (11.6 %)

5889 (11.5 %)

4592.4 (11.9 %)

 

Number of positive

0

Reference

<0.001

57,926 (64.3 %)

33,412 (65.1 %)

24,514 (63.3 %)

0.733

Regional lymph

1

0.82 (0.78–0.87)

 

10303.2 (11.4 %)

5579 (10.9 %)

4724.2 (12.2 %)

 

Nodes

2–3

0.82 (0.77–0.86)

 

9909.2 (11.0 %)

5631 (11.0 %)

4278.2 (11.0 %)

 
 

4–6

0.87 (0.81–0.93)

 

6433.9 (7.1 %)

3650 (7.1 %)

2783.9 (7.2 %)

 
 

7+

0.94 (0.86–1.01)

 

5494.7 (6.1 %)

3059 (6.0 %)

2435.7 (6.3 %)

 

Number of retrieved

<12

Reference

<0.001

18327.7 (20.3 %)

10,240 (19.9 %)

8087.7 (20.9 %)

0.931

Regional lymph

12–16

1.72 (1.64–1.80)

 

25,713 (28.5 %)

14,813 (28.9 %)

10,900 (28.1 %)

 

Nodes

17+

2.44 (2.33–2.55)

 

46026.3 (51.1 %)

26,278 (51.2 %)

19748.3 (51.0 %)

 

Grading

G1

Reference

<0.001

8274.1 (9.2 %)

4667 (9.1 %)

3607.1 (9.3 %)

0.954

 

G2

0.97 (0.91–1.02)

 

60851.4 (67.6 %)

34,630 (67.5 %)

26221.4 (67.7 %)

 
 

G3

1.74 (1.62–1.87)

 

16543.4 (18.4 %)

9599 (18.7 %)

6944.4 (17.9 %)

 
 

G4

1.92 (1.64–2.24)

 

1738.2 (1.9 %)

1035 (2.0 %)

703.2 (1.8 %)

 
 

Unknown

0.92 (0.82–1.03)

 

2659.8 (3.0 %)

1400 (2.7 %)

1259.8 (3.3 %)

 

Histology

Adenocarcinoma

Reference

<0.001

62172.7 (69.0 %)

35,607 (69.4 %)

26565.7 (68.6 %)

0.978

 

Adeno-Ca in adenomatous polyp

0.95 (0.89–1.02)

 

5139.1 (5.7 %)

2883 (5.6 %)

2256.1 (5.8 %)

 
 

Adeno-Ca in villous adenoma

2.02 (1.82–2.25)

 

2901.7 (3.2 %)

1664 (3.2 %)

1237.7 (3.2 %)

 
 

Adeno-Ca in tubulovillous adenoma

1.73 (1.62–1.85)

 

8333.5 (9.3 %)

4806 (9.4 %)

3527.5 (9.1 %)

 
 

Mucinous carcinoma

2.23 (2.10–2.37)

 

11,520 (12.8 %)

6371 (12.4 %)

5149 (13.3 %)

 

CEA

C0-stage

Reference

<0.001

31640.5 (35.1 %)

18,476 (36.0 %)

13164.5 (34.0 %)

0.763

 

C1-stage

0.88 (0.83–0.92)

 

17236.6 (19.1 %)

9804 (19.1 %)

7432.6 (19.2 %)

 
 

Unknown/Borderline

1.00 (0.96–1.04)

 

41189.8 (45.7 %)

23,051 (44.9 %)

18138.8 (46.8 %)

 

Operation

Segmental resection

Reference

<0.001

13557.3 (15.1 %)

7750 (15.1 %)

5807.3 (15.0 %)

0.447

 

Hemi/subtotal colectomy

14.3 (13.8–14.8)

 

75781.8 (84.1 %)

43,171 (84.1 %)

32610.8 (84.2 %)

 
 

Other

2.66 (2.32–3.05)

 

727.9 (0.8 %)

410 (0.8 %)

317.9 (0.8 %)

 

Year

2004 to 2006

Reference

0.285

31,052 (34.5 %)

17,527 (34.1 %)

13,525 (34.9 %)

E)

 

2007 to 2009

0.97 (0.93–1.01)

 

30,869 (34.3 %)

17,585 (34.3 %)

13,284 (34.3 %)

 
 

2010 to 2012

0.97 (0.93–1.01)

 

28,146 (31.3 %)

16,219 (31.6 %)

11,927 (30.8 %)

 

Age

Up to 49 years

Reference

<0.001

5545.6 (6.2 %)

3174 (6.2 %)

2371.6 (6.1 %)

0.995

 

50 to 64 years

1.56 (1.46–1.66)

 

21581.8 (24.0 %)

12,332 (24.0 %)

9249.8 (23.9 %)

 
 

65 to 79 years

2.65 (2.49–2.83)

 

37577.3 (41.7 %)

21,253 (41.4 %)

16324.3 (42.1 %)

 
 

80+ years

4.08 (3.80–4.39)

 

25362.3 (28.2 %)

14,572 (28.4 %)

10790.3 (27.9 %)

 

Gender

male

Reference

<0.001

40730.6 (45.2 %)

22,954 (44.7 %)

17776.6 (45.9 %)

0.570

 

female

1.30 (1.26–1.35)

 

49336.4 (54.8 %)

28,377 (55.3 %)

20959.4 (54.1 %)

 

Ethnicity

Caucasian

Reference

<0.001

72714.5 (80.7 %)

41,771 (81.4 %)

30943.5 (79.9 %)

0.050

 

African-American

1.09 (1.04–1.15)

 

11763.1 (13.1 %)

6213 (12.1 %)

5550.1 (14.3 %)

 
 

Other/Unknown

0.66 (0.62–0.70)

 

5589.4 (6.2 %)

3347 (6.5 %)

2242.4 (5.8 %)

 

Marital status

Married

Reference

0.877

47284.7 (52.5 %)

27,005 (52.6 %)

20279.7 (52.4 %)

0.930

 

Single

0.98 (0.93–1.03)

 

10609.8 (11.8 %)

6044 (11.8 %)

4565.8 (11.8 %)

 
 

Widowed

1.00 (0.95–1.05)

 

20331.9 (22.6 %)

11,580 (22.6 %)

8751.9 (22.6 %)

 
 

Other/Unknown

0.99 (0.94–1.05)

 

11840.6 (13.1 %)

6702 (13.1 %)

5138.6 (13.3 %)

 
  1. aMultivariable logistic regression with the odds ratio (OR) for right-sided carcinomas in the original raw data set (N = 91,416)
  2. AJCC American Joint Committee on Cancer, T-stage tumor stage, CEA Carcinoembryonic antigen
  3. bLikelihood ratio tests
  4. cAfter full bipartite propensity score matching with stratification for year of diagnosis and tumor stage, a multivariable conditional logistic regression based on the subgroups obtained by the matching procedure was performed. No significant bias was observed for cancer side
  5. 1349 patients were excluded because of lacking counterpart in the other group
  6. Weighted matching causes decimals for the number of patients in the group with left-sided cancer
  7. D)Excluded to avoid collinearity with the number of positive regional lymph nodes
  8. E)No statistical test because propensity score matching was stratified for year of diagnosis and tumor stage
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