Background: Population-based studies usually described a mild course of elderly-onset (>60 years) Crohn's disease (CD). However the natural history of perianal CD in this population is unknown. We aimed to describe the prevalence and the natural history of perianal CD in patients diagnosed with CD after 60 years.
Methods: All patients diagnosed with CD after the age of 60 years between 1988 and 2006 were included (n=372). Perianal CD was defined by a perianal abscess or fistula and was classified according to Cardiff classification. Logistic regression and Cox model were used to identify factors associated with perianal CD.
Results: Thirty-four patients (34/372, 9%) were diagnosed with perianal CD at diagnosis. After a median follow-up of 5.4 years [Interquartile range, 2.0–10.1], a total of 59 patients (59/372, 16%) were diagnosed with perianal CD. The 5-year cumulative probability of perianal CD was 17% [CI 95%, 13–21]. Thirty-nine percent of patients (23/59) had complex fistula. At the end of follow-up, incontinence was observed in 22% of patients with perianal CD as compared to 4% of patients without perianal CD (p=10–4). Perianal CD at diagnosis was significantly associated with 5-years immunosuppressants exposition (29.6% [9.8–45.1] vs 16.6% [12.0–21.0]; p=0.02) and with intestinal resection (54.2% vs 29.4%; p<10–3). Twenty-four percent of patients with perianal CD had definitive stoma as compared to 4.5% of patients without perianal CD (p<10–2). At diagnosis, rectal disease was significantly associated with perianal CD occurrence (Odds Ratio, 2.3 [95% CI, 1.1–4.8]). During follow-up, both isolated rectal disease (OR, 2.9 [95% CI, 1.6–5.0] and pure colonic location (L2) (OR, 8.7 [95% CI, 1.2–63,4] were significantly associated with perianal CD occurrence.
Conclusions: In a large elderly-onset population-based cohort, about 20% of patient had perianal CD. The occurrence of perianal CD was associated with pure colonic location and rectal involvement. Although these patients have received more frequently immunosuppressants, one-quarter had definitive stoma, emphasizing the value of early biologic therapy in these patients.