Published online Jul 26, 2019. doi: 10.12998/wjcc.v7.i14.1795
Peer-review started: February 26, 2019
First decision: March 28, 2019
Revised: May 8, 2019
Accepted: May 23, 2019
Article in press: May 23, 2019
Published online: July 26, 2019
Processing time: 153 Days and 20.5 Hours
An anal (or perianal) fistula is defined as an external abnormal pathological connection between the anal canal and perianal skin. The majority of anal (or perianal) fistulas are idiopathic, associated with Crohn’s disease (CD) and, to a lesser extent, other inflammatory conditions.
There is no recent data on the prevalence of anal fistula in the United Kingdom or the Europe. The frequency of underlying risk conditions in anal fistula is also poorly understood.
This real-world evidence study aimed to estimate United Kingdom- and Europe-standardized prevalence of anal fistula, with and without CD. Additionally, the study aimed to describe the prevalence of relevant comorbidities among patients with anal fistula.
A retrospective population-observational cohort study was performed using a United Kingdom primary care database. The prevalence of anal fistula by overall and CD status was calculated between 2014 and 2017. These estimates were standardized to the United Kingdom and Europe populations. Prevalence of relevant comorbidities was also reported.
Analysis estimated the United Kingdom- and Europe-standardized prevalence of anal fistula as 1.80 (95%CI: 1.65-1.94) and 1.83 (95%CI: 1.68-1.98) per 10000 patients, respectively in 2017. Between 2014-2016 the standardized point prevalence estimates ranged from 1.89 to 2.36. Analysis estimated the United Kingdom- and Europe-standardized prevalence of anal fistula without CD as 1.35 (95%CI: 1.23-1.48) and 1.39 (95%CI: 1.26-1.52) per 10000 patients. In contrast, the standardized point prevalence estimate of anal fistula with CD was lower for both United Kingdom and Europe (0.44; 95%CI United Kingdom: 0.37-0.52, 95%CI Europe: 0.37-0.51) per 10000 patients in 2017. Examining data from 2017 showed that 19% of anal fistula patients without CD and 13% of anal fistula patients with CD were associated with at least one relevant comorbidity. Data indicated that 24.5% of prevalent anal fistulas were associated with CD, whereas association with other potential comorbidities was uncommon.
This real-world evidence study estimated the United Kingdom- and Europe-standardized prevalence of anal fistula were 1.80 and 1.83 per 10000 patients, respectively in 2017. Furthermore, almost 25% of cases appeared to be associated with CD but associations with other comorbidities seemed rare.
This study presents new recent population-based data on the prevalence of anal fistula in the United Kingdom and Europe. As such, it highlights the significance of this devastating complication associated with CD and other relevant comorbidities. These prevalence estimates for anal fistula indicate a major need for novel therapeutic options for this population of patients.