Table 1. Univariable comparison of potential risk factors and confounders between cases (IBD patients who developed RCC) and controls (randomly selected IBD patients from IBDSL) for the identification of risk factors to develop RCC (case control study A).
| Variable | IBD and RCC cases (n = 180) | IBDSL (n = 1800) | Missing values (cases/IBDSL) | P-value |
|---|---|---|---|---|
| Male gender, n (%) | 114 (63.3) | 837 (46.5) | 0 | <0.001 |
| Ever smokeda, n (%) | 38 (62.3) | 421 (62.5) | 11/122 | 0.979 |
| Age at IBD diagnosis(y), median | 43 | 39 | 3/1 | 0.106 |
|
IBD typeb Ulcerative colitis, n (%) Crohn's disease, n (%) |
93 (56.4) 72 (43.6) |
1004 (55.8) 796 (44.2) |
0 |
0.885 |
|
Ulcerative colitis Extend Proctitis (E1), n (%) Left-sided colitis (E2), n (%) Pancolitis (E3), n (%) |
14 (17.5) 24 (30.0) 42 (52.5) |
243 (24.4) 472 (47.5) 279 (28.1) |
10/13 |
<0.001 |
|
Crohn's disease Extend Ileum (L1), n (%) Colon (L2), n (%) Ileocolonic (L3), n (%) Upper digestive (L4), n (%) Perianal disease activity, n (%) Phenotype Non stricturing/penetrating (B1), n (%) Stricturing (B2), n (%) Penetrating (B3), n (%) Stricturing and penetrating, n (%) |
27 (38.6) 19 (27.1) 24 (34.3) 2 (2.8) 21 (30.0) 19 (27.9) 16 (23.5) 15 (22.1) 18 (26.5) |
223 (28.1) 183 (23.0) 389 (48.9) 65 (8.2) 119 (14.9) 437 (54.9) 171 (21.5) 96 (12.1) 92 (11.6) |
2/1 1/0 2/0 4/0 |
0.054 0.106 0.001 <0.001 |
|
Medical therapy prior to RCC diagnosis 5ASA, n (%) Thiopurines, n (%) Methotrexate, n (%) Cyclosporine, n (%) Anti-TNFα therapy, n (%) |
145 (94.2) 49 (32.0) 3 (2.0) 5 (3.3) 16 (10.5) |
1605 (89.8) 717 (40.2) 95 (5.3) 26 (1.1) 350 (19.7) |
26/13 27/17 29/10 27/10 28/25 |
0.083 0.047 0.074 0.091 0.006 |
| IBD related surgery, n (%) | 86 (48.0) | 508 (28.3) | 1/8 | <0.001 |
| Calendar year of IBD diagnosis, median | 1989 | 2003 | 3/1 | <0.001 |
| Duration of follow up since IBD diagnosis (y), median | 19 | 7 | 3/30 | <0.001 |
IBD, Inflammatory bowel disease; IBDSL, IBD South Limburg cohort; RCC, renal cell carcinoma.
a
Smoking data were only available for patients with Crohn's Disease
b
Indeterminate colitis was not considered in this comparison since these patients were excluded from IBDSL