Table 1.

Paradoxical IBD in rheumatoid arthritis.

Study, Year	Number of Patients, Sex	Age/Mean Age	Treatment	Interval from Anti-TNF Onset to IBD Onset	IBD	RF, CCP Antibodies	Colonoscopy	Biopsy	Outcome
O’Toole et al., 2016 [14]	9 F + M	n/a	9 ETN	n/a	9 CD	n/a	n/a	n/a	n/a
Krishnan et al., 2015 [15]	80 F 19 M 4 n/a	51 ± 15 years	24 ADA 53 ETN 25 IFX 1 GOL	n/a	46 CD 51 UC 6 n/a	n/a	n/a	n/a	50 stopped current anti-TNF-α 33 continued current anti-TNF-α 20 unknown ±5-ASA, CS, antibiotics, ADA/IFX
Prescott et al., 2007 [16]	1 M	55 years	IFX	4 months	UC	RF+ anti CCP+	Moderately congested, erythematosus, friable and granular mucosa in the rectum, sigmoid, splenic flexure, and distal transverse colon	Chronic active colitis with acute cryptitis, crypt abscesses, architectural distortion, dense lymphoplasmacytic lamina propria infiltrate and lymphoid hyperplasia	IFX stopped CS+ Mesalamine
Tursi et al., 2008 [17]	1 F	20 years	ADA 40 mg/2 week + MTX 25 mg/week	4 months	UC	n/a	Diffuse loss of vascular pattern, edema in the mucosa, and diffuse erosions from the rectum to the splenic flexure in a continuous fashion	Cryptic abscesses, a decreased number of goblet cells, and a marked infiltration of neutrophils and lymphocytes	CS Mesalazine Probiotics
Salazar et al., 2013 [18]	1 F	37 years	ADA 40 mg/2 week	2 years	CD	n/a	Disperse and deep ulceration in right colon and lesser ulcers and erythema in rectum and a normal ileum	Compatible with CD	CS Switch to ETN Favorable outcome
Tousirrot et al., 2012 [3]	1 F	83 years	ETN 25 mg/week	33 months	CD	RF− Anti CCP+	Ileum stenosis	Mucosal inflammation with the presence of epithelioid granuloma	ETN discontinued switch to ADA Favorable outcome
Hutchings et al., 2019 [4]	1 F	30 years	ETN	8.5 years	CD	n/a	n/a	Active inflammation, architectural distortion, and pyloric gland metaplasia	Switch to ADA Favorable outcome

F = female, M = male, UC = ulcerative colitis, CD = Crohn’s disease, IFX = Infliximab, ETN = Etanercept, ADA = Adalimumab, GOL = Golimumab, RF = rheumatoid factor, CCP = cyclic citrullinated peptide antibody, CS = corticosteroids, TNF-α = tumor necrosis factor alpha, 5-ASA = 5-aminosalicylates, n/a = not available.