Outpatient Botulinum Toxin Injection for Chronic Anal Fissure: A Single-Centre Retrospective AuditAbstract
Objective Chronic anal fissure (CAF) causes significant quality of life impairment. Botulinum A toxin (Botox; brand name Dysport, Ipsen Biopharmaceuticals Inc.) injection into the anal sphincter is an established treatment. In New Zealand and Australia, anal Botox injection is often performed under general anesthesia (GA). The primary aim of the current study was to investigate the efficacy of treating CAF with outpatient anal Botox injection without sedation. The secondary aims were to assess its safety and cost-saving potential.
Materials and Methods A retrospective audit was conducted at a tertiary public hospital between 2011 and 2013. Patients diagnosed with CAF underwent an anorectal examination and received Botox injection in the outpatient clinic. Demographic and comorbidity data were recorded. Patients were followed by telephone or clinic visit after 2 weeks, and then, as required. Success was defined as symptom resolution or patient-reported improvement such that no further treatment was required.
Results A total of 163 patients were treated (median age: 40.5 years; range: 15–88 years). After 1 Botox injection, 106 patients (65.0%) reported satisfactory symptom resolution at follow-up. After 1 to 2 injections, 134 patients (82.2%) achieved symptom resolution. A total of 29 patients (17.8%) reported refractory symptoms despite 2 injections, and they were offered a third injection in the outpatient clinic or an examination under GA. No major complications were reported.
Conclusion Botox injections can effectively treat CAF in an outpatient setting, with similar success rates to injection under GA. Widespread adoption of this technique could lead to significant cost savings in healthcare resources.
Keywords
anal fissure; botulinum toxins; outpatient care; ambulatory procedures; treatment outcome
Introduction
Anal fissure is a common anorectal condition caused by trauma to the anoderm, typically from the passage of hard stool. This trauma results in a tear in the anoderm of the distal anal canal; if acute healing does not occur, a chronic anal fissure (CAF) may be established. Chronicity is defined as symptoms lasting more than 4 weeks.1 Chronic anal fissure can develop in up to 40% of patients with an acute fissure, leading to severe defecatory pain, anal bleeding, and reduced quality of life.2 Healing of CAF is thought to be prevented in most instances by a hypertonic internal anal sphincter, which can lead to local ischemia and prevent resolution.
The treatments for CAF include conservative measures such as optimization of stool consistency and topical or oral medication for symptomatic relief. The medical treatment includes topical glyceryl trinitrate (GTN) or calcium channel blockers such as diltiazem or nifedipine ointments. Cases refractory to medical therapy require more invasive intervention, including botulinum A toxin (Botox; brand name Dysport, Ipsen Biopharmaceuticals Inc.) injection to the anal sphincter or lateral sphincterotomy, with the former often favored in the modern practice due to the transient effect on internal anal sphincter function and lower chance of permanent impairment of anal continence.3,4 Anal Botox injection can provide early symptomatic relief as well as allowing the fissure to heal, resulting in long-term resolution of symptoms for approximately 65 to 75% of patients who suffer from CAF.5 Botox has been shown to have a similar efficacy to topical GTN, but without the common and significant side effect of headache, or issues with patient adherence more commonly associated with topical treatments.5,6
In most centers in New Zealand and Australia, anal Botox injections are performed under general anesthesia (GA), with obvious implications for resource consumption in resource-constrained healthcare environments. As patients wait for theatre availability, their anal fissure symptoms continue to cause quality of life impairment and may require further medical attention while waiting. To address this, anal Botox injection has been performed in the outpatient setting without sedation or GA at our tertiary public hospital, but the efficacy of this treatment in the Australia and New Zealand setting has not been demonstrated. A retrospective audit was performed, with the primary outcome being the clinical success rate, as defined by symptom resolution, of using anal Botox injection in the outpatient setting to treat CAF.
Materials and Methods
A retrospective audit was conducted of all consecutive patients seen in the tertiary public hospital Botox outpatient clinic between September 2011 and September 2013. Patients were referred from primary care or the general surgery clinic. This timeframe reflects the introduction of outpatient anal Botox injection at our tertiary public hospital, enabling assessment of the service from inception. There have been no material changes in the Botox injection technique, dosing strategy, or surgeon expertise at our institution since 2011; therefore, the outcomes from this early cohort remain directly applicable to the contemporary practice. Notably, including patients treated during the establishment of this service provides meaningful insight into the learning-curve period, which may support implementation in centers developing similar outpatient programs.
Following an anorectal examination confirming an anal fissure, Botox injection was performed by an experienced consultant colorectal surgeon at the same appointment, without sedation. The procedure routinely involved diluting a 500-unit vial of botulinum toxin type A in 5 mL of 0.9% sodium chloride. Using 0.4-mL syringes with a 26-G needle, 0.2 mL (20 units) is injected at the 3 o'clock and 9 o'clock positions, 2 to 3 mm from the anal verge, giving a total dose of 40 units per patient. The patient is placed in the left lateral position, and the anus is cleaned with chlorhexidine prior to injection. Patients are also routinely advised to maintain regular bowel habits and encouraged to take supplemental fiber such as psyllium husk each morning.
Routine follow-up was scheduled at 2 weeks, either in person or via a nurse-led phone call, to assess symptom resolution. If the symptoms persisted, a repeat clinic appointment was arranged. Longer-term outcomes were obtained from clinical records, with follow-up extending to a minimum of 12 months and up to 36 months. Data collected included age, sex, ethnicity, smoking status, diabetes, presenting symptoms, and history of anorectal disorders. Patients with known inflammatory bowel disease were excluded.
Ethical Approval
The present study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki. Formal exemption from ethical approval was obtained from the New Zealand Health and Disability Ethics Committee as the study was deemed audit-related activity. Institutional approval was obtained from the local hospital research office prior to data collection. Individual patient consent was waived due to the retrospective audit design.
Results
During the study period, 210 patients were assessed in the Botox clinic at the tertiary public hospital. Two patients were excluded due to known Crohn's disease, and 45 were excluded after no anal fissure was identified on examination. The remaining 163 patients formed the study cohort. Of these, 54 (33.5%) were male, with a median age of 40.5 (range 15–88) years. A total of 109 patients (66.9%) identified as New Zealand European, and 16 (9.8%), as New Zealand Māori. Patient demographics are summarized in Table 1. In total, 111 (68.1%) patients presented with anorectal pain alone. At the time of their Botox injection, 20 (12.3%) patients were smokers, and 20 (12.3%) patients had diabetes. The presenting complaint and selected medical/surgical history is shown in Table 1.
All patients were retrospectively followed for at least 12 months, with some followed for up to 3 years. Of the 163 patients treated, 106 (65.0%) reported complete resolution of symptoms after a single Botox injection, and they were discharged from the clinic (Figure 1). Among these, 26 did not respond to follow-up phone calls but, given there was no evidence of representation, they were deemed to have achieved clinical resolution. The remaining 57 34.9% patients reported persistent symptoms and were offered a second Botox injection. In total, 134 patients (82.2%) experienced complete symptom resolution after receiving 1 or 2 Botox injections, while 29 patients (17.8%) reported refractory symptoms and were offered either a third Botox injection or an examination under anesthesia (Figure 1).
Discussion
In the current single-institution series, 163 (65.0%) patients reported clinical resolution of symptoms of CAF after a single anal Botox injection and 134 (82.2%) experienced resolution after up to 2 injections, which were performed without sedation in an outpatient clinic in a New Zealand public hospital. These findings suggest outpatient anal Botox injection is feasible and can achieve success rates comparable to those of injection under GA.7 Patients who attend a ‘see-and-treat' outpatient clinic benefit from significantly-reduced waiting times for treatment, enabling prompt improvement in quality of life and avoiding the risks of GA or sedation. The potential healthcare resource savings from the widespread adoption of this technique is significant.
While outpatient anal Botox injection is not widely practiced in Australia and New Zealand, a recent European audit of 1,003 patients by Brisinda et al.7 found 77% experienced complete fissure healing 2 months after receiving Botox injections in an outpatient clinic, an excellent outcome when compared to success rates after injection under GA, which are reported to be of approximately 65 to 70%.8 The current study demonstrates lower healing rates compared to the European population, particularly considering the outcome was clinical resolution of symptoms rather than clinically-confirmed fissure healing. Brisinda et al.7 used higher doses of Botox for many patients and described a positive relationship between increasing dose and healing rates, although lower sphincter pressures were also associated with higher dosing, suggesting a potential trade-off in efficacy and complications. Patient acceptability is likely to vary among different populations due to societal factors such as patient expectation and acceptability of an uncomfortable, invasive procedure; therefore, examining data from the New Zealand context is important. The fact that the clinical success rate in the current study was comparable to the reported success rates of anal Botox injection under GA supports the practice of outpatient anal Botox injection.
Increasing adoption of outpatient anal Botox injection to treat a condition traditionally managed in the operating theatre promises substantial cost savings for healthcare systems. When performed under GA, the combined cost of a day-case procedure is estimated to be oif $5,602 NZD in our tertiary public hospital. In contrast, outpatient anal Botox injection reduces the cost to approximately $381 NZD (1 vial of Dysport is routinely used to treat two patients). These costs will vary between institutions. However, a formal cost–benefit analysis was not performed, as the substantial difference in estimated procedural costs suggests that outpatient anal Botox injection may offer considerable economic advantages compared with treatment under GA. This represents a potential 90 to 95% reduction in cost, by avoiding the high costs associated with operating theatre use, GA, and postanesthetic recovery time. These savings can be reallocated to other areas within the healthcare system, enhancing overall resource efficiency and enabling more patients to receive timely effective treatment. Outpatient anal Botox injection may also reduce loss of productive days (in paid employment or unpaid and domestic labor) by avoiding GA and enabling patients to carry out other activities of daily living such as work or childcare before and/or after the outpatient appointment. Broader implementation of outpatient anal Botox injection represents a promising opportunity for the delivery of cost-effective, patient-centered care in advanced healthcare systems. There is also opportunity in severely resource-constrained health systems in the developing world, where lateral sphincterotomy may still be used as the first-line treatment due to the material cost of Botox, and based on the assumption that both techniques would be performed under GA.
Patient-reported outcome measures (PROMs) are increasingly recognized as a key component of quality of life studies in surgery,8,9 and they should be applied to the investigation of anal fissure, which in essence is problematic only because of its significant quality of life impairment. Although the present study relied on patient-reported symptom resolution as a marker of clinical success, it was a very rudimentary assessment from a time before robust PROMs methodology was widely used. The current study's design prevented robust PROM assessment, and because conservative management of anal fissure has been associated with improved PROMs, future prospective studies examining PROMs in this context should consider a comparative group of conservative management.10
Botox injection for anal fissure is generally considered safe and well-tolerated, with a known lethal dose of 3,000 units in a 70-kg male.11 A dose of 40 units of Botox is commonly used for the treatment of CAF in Australia and New Zealand, but this is likely to vary significantly, and there are no consensus guidelines on optimal dosing. However, 2 systematic reviews12,13 have suggested that a lower dose (≤ 20 units) is preferable due to increased risk of anal incontinence with higher dosing (> 20 units); the dose used in the current study would be considered a lower dose by these criteria. The current study's design is likely to underestimate the incidence of fecal incontinence due to follow-up procedures which relied on self-reporting of symptoms; future studies should allow structured prospective assessment of fecal incontinence using validated measures for patients receiving anal Botox injection. No adverse effects were documented in the clinical notes of patients in the present study, including no perianal abscesses, and while complications may have been missed due to loss to follow-up, there were no serious complications, including perianal abscess drainage, identified from the medical records in a catchment area with no other acute general surgical services, suggesting any complications were likely to be minor or infrequent.
The major strength of the present study is its real-world applicability, as this was an audit of public surgical practice in New Zealand; however, there are several limitations. It is a retrospective observational study without a comparison group; long-standing institutional practice prevented a comparison group, and to compare among different institutions introduces potential bias. Patient-reported outcome measures were not collected, and clinical success was defined by patient-reported symptom resolution rather than confirmed fissure healing on examination. A further limitation is the assumption of clinical resolution for the 23 patients lost to follow-up after 1 Botox injection. It is possible some did not re-engage with the service due to poor tolerance of the procedure, leading to overestimation of the success rate. Prospective studies incorporating validated PROMs are warranted to provide a more comprehensive evaluation of this technique, including formal assessment of patient acceptability. Although the study period reflects the first years of our outpatient Botox service (2011–2013), technique, dosing, and operator consistency over the subsequent decade supports the relevance of these findings to the ongoing practice. Earlier experience also reflects the real-world learning curve, which is beneficial for institutions seeking to newly adopt outpatient Botox pathways. The incidence of New Zealand Māori in the former Waikato District Health Board catchment is of 23%;14 the comparatively low incidence of New Zealand Māori in the current study warrants further investigation, as it may reflect a lower incidence of CAF in New Zealand Māori, but it perhaps more likely reflects poorer access to healthcare.15,16
Conclusion
Outpatient anal Botox injection without sedation offers an effective and safe treatment for chronic anal fissure, with clinical success rates comparable to the published rates for resolution after Botox injection under GA. This treatment is feasible in a New Zealand public hospital setting, although further work is required to assess PROMs. Widespread adoption of outpatient anal Botox injection has the potential to deliver significant cost savings, reduce surgical waiting times, and improve patient access to timely care, while maintaining acceptable clinical outcomes.
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**
The present work was delivered as an oral presentation at the Royal Australasian College of Surgeons 92nd Annual Scientific Congress, Ōtautahi Christchurch, 6–10 May 2024.
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Funding
The authors declare that they did not receive funding from agencies in the public, private, or non-profit sectors to conduct the present study.
Data Availability
Data will be available upon request to the corresponding author.
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