The 5-year outcomes and predictors of healing in chronic anal fissure treated with botulinum toxin: a retrospective analysis of 199 cases.

Background: Botulinum toxin (BT) is a nonsurgical alternative to lateral internal sphincterotomy (LIS). While there are promising results, there is still a gap in knowledge regarding long-term outcomes and the predictors for healing after BT.

Methods: Chronic anal fissure (CAF) patients treated with 100 IU BT with a minimum 5-year follow-up were analyzed retrospectively. Patients with persistent or recurrent fissures after their first BT injection were offered either a second BT injection or LIS. Healing was defined as complete symptom resolution with fissure epithelization. The primary outcome measure was recurrence-free healing rate with BT at 5 years. Predictors of healing were assessed by logistic regression analysis.

Results: The mean age was 33.8 ± 10 years, and 139 (69.5%) patients were female. The complete healing rate at 5 years was 73.8% and 26.2% for the patients that underwent LIS. Multivariate analysis for LIS likelihood revealed that female gender (odds ratio, OR: 0.48, 95% confidence intervals, CI 0.25-0.92, p = 0.028), absence of chronic constipation (OR: 0.09, 95% CI 0.03-0.25, p = < 0.0001), and shorter constipation duration (OR: 1.10, 95% CI 1.06-1.13, p = < 0.0001) were predictors for recurrent-free healing after BT at 5-years. A cutoff value of 10 months of constipation yielded an accuracy of 88% for predicting nonhealing with BT (AUC: 0.881). BT-related incontinence was mild and resolved within 2 months, while LIS resulted in 19.2% permanent incontinence at 5 years.

Conclusions: BT is an effective and safe treatment for CAF, with acceptable long-term outcomes and minimal incontinence risk. Constipation duration and gender are key predictors of healing, aiding patient selection. Male patients with prolonged constipation may benefit from earlier consideration of LIS.