Prevalence of anal fistula in the United Kingdom

Table 4 Prevalence of comorbidities in anal fistula with and without Crohn’s disease

	2014		2015		2016		2017
	without CD	with CD	without CD	with CD	without CD	with CD	without CD	with CD
Prevalence of AF, n	891	252	726	212	514	172	437	142
Prevalence of AF with any comorbidity	148	39	124	28	96	26	82	18
per 10000 patients	0.30	0.08	0.29	0.07	0.27	0.07	0.26	0.06
per 100 AF patients	16.61	15.48	17.08	13.21	18.68	15.03	18.76	12.68
Prevalence of comorbidities per 100 AF patients1
HIV	0	###	###	###	0	###	###	###
Anal carcinoma	###	0	###	0	###	0	###	0
Radiation in the pelvic area	1.91	###	1.79	###	1.75	###	3.43	###
Diabetes mellitus type 1 or 2	8.98	5.16	8.13	5.19	10.12	5.20	8.92	4.93
Diverticulitis, colon/rectum	4.38	###	4.96	###	5.84	3.47	5.26	###
Hidradenitis suppurativa	0.90	###	1.38	###	1.95	3.47	1.60	4.23
Proctitis	1.46	4.76	2.20	3.77	1.36	4.62	1.83	###
Congenital anal fistula	0	0	###	0	0	0	0	0

AF: Anal fistula; n: Number; HIV: Human immunodeficiency virus;

¹No patients with anal tuberculosis, anal syphilis, anal gonorrhoea, anal chlamydia, lymphogranuloma venereum were detected; ### masking due to small patient numbers (n: 1-5).