Risk factors associated with the development of chronic pouchitis following ileal-pouch anal anastomosis surgery for ulcerative colitis

Table 1 Studies which were included in meta-analysis, n (%)

Ref.	Population	Number of IPAA	Normal pouch1	Chronic pouchitis	Follow up period after IPAA	Definition of chronic pouchitis
Abdelrazeq et al[3], 2008	York Hospital, Huddersfield Royal Infirmary, Derby Hospitals–prospective	198	134 (68)	29 (15)	Mean 64 months (range: 12-180 months)	Presence of active symptoms continuously for more than 4 weeks despite full dose of standard therapy or required more than 2 weeks of therapy every month for three consecutive months to achieve symptomatic control
Achkar et al[15], 2005	Cleveland Clinic Foundation–prospective case control study	120	40 (33)	40 (33)	Mean 5.2 years	Presence of 4 or more episodes of pouchitis per year, or active symptoms lasting continuously for more than 4 weeks despite antibiotic therapy, or chronic antibiotic or anti-inflammatory therapy to control symptoms of pouchitis
Ferrante et al[16], 2008	University Hospital Gasthuisberg–retrospective	173	92 (53)	33 (19)	Median 6.5 years (range: 34-9.9 years)	Presence of active symptoms lasted for more than 4 weeks, despite standard therapy
Fleshner et al[17], 2007	Cedars-Sinar Medical Centre–prospective	186	127 (68)	23 (12)	Median 24 months (range: 3-117 months)	Required continuous antibiotic treatment for symptom relief or did not respond to antibiotic treatment
Hashavia et al[18], 2012	Tel-Aviv Sourasky Medical Centre– prospective	201	-	63 (31)	Mean 107 months	Presence of at least 4 weeks of persistent symptoms and dependent on prolonged therapy of more than two different antibiotics, or those who did not respond to antibiotics
Lian et al[19], 2009	Cleveland Clinic Foundation–retrospective	251	35 (14)	29 (12)	-	Failed to respond to a 2-4 weeks course of a single antibiotic, or required therapy over 4 weeks with 2 antibiotics
Okita et al[20], 2013	Mie University–retrospective	231	165 (71)	31 (13)	Median 1882.5 days (range: 31-4465 days)	Required long-term, continuous antibiotic therapy to maintain remission, or relapsing episodes (> 3 per year), or failed to respond to antibiotics
Scarpa et al[21], 2011	University of Padova–prospective	32	-	6 (19)	Median 23 months	No response to first line antibiotic therapy and required continuous antibiotic treatment for symptom relief or had a treatment resistant form
Uchino et al[22], 2013	Hyogo College of Medicine–retrospective	772	695 (90)	29 (4)	Median 5.67 years (range: 152-10.81 years)	Failed to respond to a 4-week course of a single antibiotic, requiring prolonged therapy for ≥ 4 weeks with ≥ 2 antibiotics or topical corticosteroid therapy
Werner et al[23], 2013	Tel Aviv Medical Centre–prospective	36	10 (28)	13 (36)	Follow up period was not mentioned	Required antibiotic or anti-inflammatory therapy for at least 4 weeks, or patients having more than 5 flares of pouchitis per year
Wu et al[24], 2016	Cleveland Clinic Pouch Centre–prospective	1564	181 (12)	217 (14)	Median 9 years (range: 4-14 years)	Symptoms lasted for 4 weeks or more and failed to respond to a 4-week course of single antibiotic therapy

¹Normal pouch: Normal pouch cases do not include acute pouchitis.

IPAA: Ileal pouch anal anastomosis.