Epidemiology, treatment patterns, and associated risk factors in perianal fistulizing Crohn’s disease: A systematic literature review

Table 1 Definitions of complex Crohn’s perianal fistulas from included studies

Included in definitions for complex CPF	Number of studies
Multiple fistula tracts/external openings1	18
Presence of rectovaginal fistula1	17
High position1	16
High transsphincteric1	16
Signs of perianal abscess (including pain or fluctuation)1	16
High intersphincteric1	15
Anorectal stricture1	14
Suprasphincteric1	13
Extrasphincteric1	12
Endoscopic activity1	6
Supralevator extension	3
Proctitis	2
Horseshoe fistula	2
Procedure as surrogate for complex CPF (ostomies, seton drainage)	2
Perianal disease activity index (not further defined)	1
Translevator extension	1

¹Included in the definition of complex Crohn’s perianal fistulas by the American Gastroenterological Association.

CPF: Crohn’s perianal fistulas.

Table 2 Summary of healing and failure rates for the top five most frequently reported intervention categories

Frequency of healing or failure category, range (number of articles)
	‘Healing’		‘Failure’
Category	Fistula healing/closure	Partial response	Active disease after treatment	Recurrence
Biologics	8.8%-78.4% (n = 17)	11.9%-68.3% (n = 7)	10.7%-55.6% (n = 10)	7.9%-45.0% (n = 5)
Loose seton	17.7%-60.5% (n = 5)	25.0% (n = 1)	41.7%-51.0% (n = 2)	4.0%-68.0% (n = 5)
Surgery (other than seton)	40.7%-75.0% (n = 6)	15.5%-41.6% (n = 3)	22.5%-42.0% (n = 3)	39.5%-64.0% (n = 3)
Immunosuppressants	25.0%-54.8% (n = 3)	19.1% (n = 1)	9.5% (n = 1)	28.6%-46.9% (n = 3)
Fistulectomy/-otomy	47.9%-90.3% (n = 4)	Not reported	3.4% (n = 1)	17.9% (n = 1)

Data presented are for the two most frequently identified healing and failure categories. Details of all the interventions for which healing and failure were assessed can be found in Supplementary Table 4.

Table 3 Summary of overall healing and failure rates per category

	Articles, n	Sample size	Healing/failure1	Follow-up time/time to failure (months)
Healing category
Fistula healing/closure	14	50-253	25.0%-63.2%	12.0-85.2
Partial healing/improvement	3	58-65	10.5%-17.0%	12-45
Radiological healing	3	60-253	18.0%-57.0%	12-48
Failure-free	4	51-157	48.7%-80.2%	12-60
Failure category
Active disease after treatment	4	61-91	15.4%-47.7%	12-31
Additional surgery	4	51-365	13.8%-45.6%	6.8-90.0
Deterioration	1	22	22.0%	45.6
Discontinuation	1	12	12.0%	6
Loss of response	1	236	73.0%	48.0
Recurrence of CPF	15	50-161	3.6%-83.0%	5.5-120.0
Treatment change/escalation	1	51	43.1%	7

¹If cumulative probability of healing at several time points was provided, only the first time point was considered in the range of percent healing.

CPF: Crohn’s perianal fistulas.