Loss of production and animal health costs in assessing economic burden of animal disease.

This article focuses on identifying the loss of production and costs (or lack thereof) associated with livestock health as well as animal disease externalities, with the intent to estimate economy-wide burden. It limits its scope to terrestrial livestock and aquaculture, wherein economic burden is predominately determined by market forces. Losses and costs are delineated into both direct losses and costs and indirect losses and costs, as well as ex post costs and ex ante costs. These costs include not only private expenditures but also public expenditures related to the prevention of, treatment of, and response to livestock disease. This distinction is important because a primary role of government is to mitigate externalities. The article then discusses market impacts and investments. Finally, it provides selected examples and illustrative observations and discusses future directions for research and application.

Cet article examine les pertes de production et les coûts associés (ou non) à la santé animale ainsi que les externalités liées aux maladies animales, dans le but d'estimer le fardeau pour l'ensemble de l'économie. L'examen se limite à la production d'animaux terrestres et aquatiques, secteurs où le fardeau économique est principalement déterminé par les forces du marché. Les pertes et les coûts sont répartis en pertes et coûts directs et indirects, ainsi qu'en coûts ex post et ex ante. Ces coûts comprennent non seulement les dépenses privées, mais aussi les dépenses publiques liées à la prévention, au traitement et aux réponses aux maladies des animaux d'élevage. Il s'agit d'une distinction importante car l'une des fonctions premières d'un gouvernement est d'atténuer les externalités. Les auteurs examinent ensuite les impacts sur les marchés et les investissements. Pour conclure, à partir d'exemples choisis et d'observations illustrant leur propos, les auteurs proposent des voies d'exploration pour la recherche et ses applications.

Este artículo se centra en determinar las pérdidas de producción y los costos (o la ausencia de ellos) asociados con las externalidades de la sanidad del ganado y las enfermedades animales, con el objetivo de estimar su impacto en toda la economía. El ámbito del artículo se limita a la ganadería terrestre y la acuicultura, donde el impacto económico está principalmente determinado por las fuerzas del mercado. Las pérdidas y los costos se clasifican en pérdidas y costos directos e indirectos, así como en costos ex post y ex ante. Dichos costos incluyen no solo los gastos privados, sino también los gastos públicos relacionados con la prevención y el tratamiento de las enfermedades del ganado y la respuesta ante estas, una distinción que es importante habida cuenta de que una de las principales funciones del gobierno es mitigar las externalidades. En el artículo se analizan a continuación las repercusiones en el mercado y las inversiones y, por último, se presentan algunos ejemplos y observaciones ilustrativas y se examinan las orientaciones futuras de la investigación y sus aplicaciones.

Getting the most out of MRI in perianal fistula: update on surgical techniques and radiological features that define surgical options.

Perianal fistulas affect approximately 2 in 10,000 people, causing symptoms such as pain and discharge, which can have a debilitating effect on a patient's quality of life. Surgical treatment, which can offer a potential cure or palliation of symptoms, must be considered carefully in cases with extensive sphincter involvement. In complex cases, the use of preoperative magnetic resonance imaging (MRI) can help to determine the best course of operative action. This review describes common and contemporary surgical procedures for perianal fistula, highlighting technical features, as well as important surgical considerations associated with each method and how these can be assessed radiologically. We focus on the anatomical features and MRI findings that take procedural elements into account and help determine the most appropriate method of treatment. The aim of this article is to provide a basis for informed and focused discussion between surgeons and radiologists to ensure the most appropriate procedure is selected for each case, with the ultimate aim of obtaining the most favourable outcomes for patients.

Heterogeneity in outcome selection, definition and measurement in studies assessing the treatment of cryptoglandular anal fistula: findings from a systematic review.

BACKGROUND: Treatment for cryptoglandular anal fistula (AF) is challenging and a lack of uniform outcomes in the literature prevents direct comparison of treatments. This can be addressed by developing a core outcome set, a standardised set of outcomes reported in all interventional studies for a specific condition. The aim of this systematic review is to assess the range of outcomes, their definitions, and the measurement instruments currently utilised in interventional studies for adult patients with AF. This will inform the development of an AF core outcome set. METHODS: Medline, Embase and The Cochrane Library were searched to identify all patient- and clinician-reported outcomes in studies assessing medical, surgical or combination treatment of adult patients with AF published from January 2008 to May 2020. The resulting outcomes were categorized according to the Core Outcome Measurement in Effectiveness Trials (COMET) taxonomy to better understand their distribution. RESULTS: In total, 155 studies were included, 552 outcomes were extracted, with a median of three outcomes (interquartile range 2-5) per study. Only 25% of studies demonstrated high-quality outcome reporting. The outcomes were merged into 52 unique outcomes and structured into four core areas and 14 domains, with the majority in the domain of physiological or clinical (gastrointestinal) outcomes. The most commonly reported outcomes were healing (77%), incontinence (63%), and recurrence (40%), with no single outcome assessed across all studies. There was a wide variation in outcome definitions and measurement instruments used. CONCLUSIONS: There is substantial heterogeneity in outcomes, definitions, and measurement instruments reported in interventional studies for cryptoglandular anal fistula. This emphasises the need for standardised outcome reporting and measurement.

Perianal fistula and the ileoanal pouch - different aetiologies require distinct evaluation.

AIM: Restorative proctocolectomy has been widely adopted as the procedure of choice for restoring gastrointestinal continuity following proctocolectomy. It is often associated with improved quality of life and high patient satisfaction; however, the development of a pouch anal fistula can cause significant morbidity. Pouch fistulas are notoriously difficult to treat and there is great heterogeneity in the management reported of these fistulas. A lack of classification, and the assumption that fistulas originating from completely different aetiologies will behave and respond similarly to a particular treatment strategy, precludes meaningful comparison of management outcomes. We aim to introduce consistency in the reporting of pouch fistulas using a novel classification system. METHODS: A consensus process involving clinicians experienced in the management of pouch fistulas from two high volume tertiary centres was performed. RESULTS: We propose that pouch anal fistulas should be classified into four distinct groups according to their aetiology: group 1, anastomotic related; group 2, inflammatory bowel disease related, with sub-classifications Crohn's (type A) and non-Crohn's (type B) in origin; group 3, cryptoglandular related; and group 4, malignancy related. CONCLUSION: Classification of pouch fistulas according to their aetiology will provide consistency in the literature and improve the quality of prospective evidence for the management of pouch fistulas.

The development of a cryptoglandular Anal Fistula Core Outcome Set (AFCOS): an international Delphi study protocol.

PURPOSE: Cryptoglandular anal fistula is a disorder with an incidence of around 1 per 5,000 people per year in European countries. Many studies have been conducted to evaluate the effectiveness of interventions for anal fistula. However, there is considerable heterogeneity in the outcomes assessed and reported in these studies. This limits research quality and complicates evidence synthesis. A solution for heterogeneity in outcome reporting is the development of a Core Outcome Set (COS). This paper describes the protocol for the development of a European COS for Anal Fistula (AFCOS). METHODS: The first step will be a systematic review of the literature to identify potential outcomes that may be included in the COS. Patient interviews will be conducted in The United Kingdom and The Netherlands to ensure that both clinician-important and patient-important outcomes are captured. The outcomes will be categorized using the COMET taxonomy and taken forward to a Delphi consensus exercise. In up to three web-based Delphi surveys the outcomes will be prioritized by patients, clinicians (surgeons, gastroenterologists, and radiologists), and (clinical) researchers. The responses will be summarized and reported anonymously in subsequent round(s) facilitating convergence to a consensus opinion. The final COS will be decided during a face-to-face consensus meeting with patients, clinicians, and (clinical) researchers. DISCUSSION: This study protocol describes the development of a European COS for anal fistula to improve research quality, evidence synthesis, and patient care.

Contemporary surgical practice in the management of anal fistula: results from an international survey.

BACKGROUND: Management of anal fistula (AF) remains challenging with many controversies. The purpose of this study was to explore current surgical practice in the management of AF with a focus on technical variations among surgeons. METHODS: An online survey was conducted by inviting all surgeons and physicians on the membership directory of European Society of Coloproctology and American Society of Colon and Rectal Surgeons. An invitation was extended to others via social media. The survey had 74 questions exploring diagnostic and surgical techniques. RESULTS: In March 2018, 3572 physicians on membership directory were invited to take part in the study 510 of whom (14%) responded to the survey. Of these respondents, 492 (96%) were surgeons. Respondents were mostly colorectal surgeons (84%) at consultant level (84%), age ≥ 40 years (64%), practicing in academic (53%) or teaching (30%) hospitals, from the USA (36%) and Europe (34%). About 80% considered fistulotomy as the gold standard treatment for simple fistulas. Endorectal advancement flap was performed using partial- (42%) or full-thickness (44%) flaps. Up to 38% of surgeons performed ligation of the intersphincteric fistula tract (LIFT) sometimes with technical variations. Geographic and demographic differences were found in both the diagnostic and therapeutic approaches to AF. Declared rates of recurrence and fecal incontinence with these techniques were variable and did not correlate with surgeons' experience. Only 1-4% of surgeons were confident in performing the most novel sphincter-preserving techniques in patients with Crohn's disease. CONCLUSIONS: Profound technical variations exist in surgical management of AF, making it difficult to reproduce and compare treatment outcomes among different centers.

Systematic review and meta-analysis of endorectal advancement flap and ligation of the intersphincteric fistula tract for cryptoglandular and Crohn's high perianal fistulas.

Background: High perianal fistulas require sphincter-preserving surgery because of the risk of faecal incontinence. The ligation of the intersphincteric fistula tract (LIFT) procedure preserves anal sphincter function and is an alternative to the endorectal advancement flap (AF). The aim of this study was to evaluate outcomes of these procedures in patients with cryptoglandular and Crohn's perianal fistulas. Methods: A systematic literature search was performed using MEDLINE, Embase and the Cochrane Library. All RCTs, cohort studies and case series (more than 5 patients) describing one or both techniques were included. Main outcomes were overall success rate, recurrence and incontinence following either technique. A proportional meta-analysis was performed using a random-effects model. Results: Some 30 studies comprising 1295 patients were included (AF, 797; LIFT, 498). For cryptoglandular fistula (1098 patients), there was no significant difference between AF and LIFT for weighted overall success (74·6 (95 per cent c.i. 65·6 to 83·7) versus 69·1 (53·9 to 84·3) per cent respectively) and recurrence (25·6 (4·7 to 46·4) versus 21·9 (14·8 to 29·0) per cent) rates. For Crohn's perianal fistula (64 patients), no significant differences were observed between AF and LIFT for overall success rate (61 (45 to 76) versus 53 per cent respectively), but data on recurrence were limited. Incontinence rates were significantly higher after AF compared with LIFT (7·8 (3·3 to 12·4) versus 1·6 (0·4 to 2·8) per cent). Conclusion: Overall success and recurrence rates were not significantly different between the AF and LIFT procedure, but continence was better preserved after LIFT.

The treatment of anal fistula: second ACPGBI Position Statement - 2018.

It is over 10 years since the first ACPGBI Position Statement on the management of anal fistula was published in 2007. This second edition is the result of scrutiny of the literature published during this time; it updates the original Position Statement and reviews the published evidence surrounding treatments for anal fistula that have been developed since the original publication.

Review article: pathogenesis of Crohn's perianal fistula-understanding factors impacting on success and failure of treatment strategies.

BACKGROUND: Evidence from groups who have studied fistula aetiology and extrapolation from interventional studies supports a multifactorial hypothesis of Crohn's perianal fistula, with several pathophysiological elements that may contribute to fistula formation, persistence and resistance to treatment. AIM: An evidence synthesis of current understanding of pathophysiological factors underlying Crohn's perianal fistula is presented, exploring the fundamental reasons why some treatments succeed and others fail, as a means of focussing clinical knowledge on improving treatment of Crohn's perianal fistula. METHODS: Evidence to support this review was gathered via the Pubmed database. Studies discussing pathophysiological factors underpinning perianal fistula, particularly in Crohn's disease, were reviewed and cross-referenced for additional reports. RESULTS: Pathophysiological factors that impact on success or failure of interventions for Crohn's perianal fistulae include the high-pressure zone, obliterating the dead space, disconnecting the track from the anus, removing epithelialisation, eradicating sepsis and by-products of bacterial colonisation, correcting abnormalities in wound repair and removing the pro-inflammatory environment which allows fistula persistence. Most current interventions for Crohn's perianal fistulae tend to focus on a single, or at best two, aspects of the pathophysiology of Crohn's anal fistulae; as a result, failure to heal fully is common. CONCLUSIONS: For an intervention or combination of interventions to succeed, multiple factors must be addressed. We hypothesise that correct, timely and complete attention to all of these factors in a multimodal approach represents a new direction that may enable the creation of an effective treatment algorithm for Crohn's anal fistula.

Short-term efficacy and safety of three novel sphincter-sparing techniques for anal fistulae: a systematic review.

BACKGROUND: The surgical treatment of complex anal fistulae, particularly those involving a significant portion of the anal sphincter in which fistulotomy would compromise continence, is challenging. Video-assisted anal fistula treatment (VAAFT), fistula tract laser closure (FiLaC™) and over-the-scope clip (OTSC®) proctology system are all novel sphincter-sparing techniques targeted at healing anal fistulae. In this study, all published articles on these techniques were reviewed to determine efficacy, feasibility and safety. METHODS: A systematic search of major databases was performed using defined terms. All studies reporting on experience of these techniques were included and outcomes (fistula healing and safety) evaluated. RESULTS: Eighteen studies (VAAFT-12, FiLaC™-3, OTSC®-3) including 1245 patients were analysed. All were case series, and outcomes were heterogeneous with follow-up ranging from 6 to 69 months and short-term (< 1 year) healing rates of 64-100%. Morbidity was low with only minor complications reported. There was one report of minor incontinence following the first reported study of FiLaC™, and this was treated successfully at 6 months with rubber band ligation of hypertrophied prolapsed mucosa. There are inconsistencies in the technique in studies of VAAFT and FiLaC™. CONCLUSIONS: All three techniques appear to be safe and feasible options in the management of anal fistulae, and short-term healing rates are acceptable with no sustained effect on continence. There is, however, a paucity of robust data with long-term outcomes. These techniques are thus welcome additions; however, their long-term place in the colorectal surgeon's armamentarium, whether diagnostic or therapeutic, remains uncertain.

Natural history of anorectal sepsis.

BACKGROUND: Progression from anorectal abscess to fistula is poorly described and it remains unclear which patients develop a fistula following an abscess. The aim was to assess the burden of anorectal abscess and to identify risk factors for subsequent fistula formation. METHODS: The Hospital Episode Statistics database was used to identify all patients presenting with new anorectal abscesses. Cox regression analysis was undertaken to identify factors predictive of fistula formation. RESULTS: A total of 165 536 patients were identified in the database as having attended a hospital in England with an abscess for the first time between 1997 and 2012. Of these, 158 713 (95·9 per cent) had complete data for all variables and were included in this study, the remaining 6823 (4·1 per cent) with incomplete data were excluded from the study. The overall incidence rate of abscess was 20·2 per 100 000. The rate of subsequent fistula formation following an abscess was 15·5 per cent (23 012 of 148 286) in idiopathic cases and 41·6 per cent (4337 of 10 427 in patients with inflammatory bowel disease (IBD) (26·7 per cent coded concurrently as ulcerative colitis; 47·2 per cent coded as Crohn's disease). Of all patients who developed a fistula, 67·5 per cent did so within the first year. Independent predictors of fistula formation were: IBD, in particular Crohn's disease (hazard ratio (HR) 3·51; P < 0·001), ulcerative colitis (HR 1·82; P < 0·001), female sex (HR 1·18; P < 0·001), age at time of first abscess 41-60 years (HR 1·85 versus less than 20 years; P < 0·001), and intersphincteric (HR 1·53; P < 0·001) or ischiorectal (HR 1·48; P < 0·001) abscess location compared with perianal. Some 2·9 per cent of all patients presenting with a new abscess were subsequently diagnosed with Crohn's disease; the median time to diagnosis was 14 months. CONCLUSION: The burden of anorectal sepsis is high, with subsequent fistula formation nearly three times more common in Crohn's disease than idiopathic disease, and female sex is an independent predictor of fistula formation following abscess drainage. Most fistulas form within the first year of presentation with an abscess.

Systematic review of surgical interventions for Crohn's anal fistula.

BACKGROUND: Anal fistula occurs in approximately one in three patients with Crohn's disease and is typically managed through a multimodal approach. The optimal surgical therapy is not yet clear. The aim of this systematic review was to identify and assess the literature on surgical treatments of Crohn's anal fistula. METHODS: A systematic review was conducted that analysed studies relating to surgical treatment of Crohn's anal fistula published on MEDLINE, Embase and Cochrane databases between January 1995 and March 2016. Studies reporting specific outcomes of patients treated for Crohn's anal fistula were included. The primary outcome was fistula healing rate. Bias was assessed using the Cochrane ROBINS-I and ROB tool as appropriate. RESULTS: A total of 1628 citations were reviewed. Sixty-three studies comprising 1584 patients were ultimately selected in the analyses. There was extensive reporting on the use of setons, advancement flaps and fistula plugs. Randomized trials were available only for stem cells and fistula plugs. There was inconsistency in outcome measures across studies, and a high degree of bias was noted. CONCLUSION: Data describing surgical intervention for Crohn's anal fistula are heterogeneous with a high degree of bias. There is a clear need for standardization of outcomes and description of study cohorts for better understanding of treatment options.

Managing perianal Crohn's fistula in the anti-TNFα era.

Perianal fistulas in Crohn's disease are common and difficult to treat. Their aetiology is poorly understood. Assessment is clinical, endoscopic and radiological, and management is undertaken by a multidisciplinary team of gastroenterologists, surgeons and radiologists. Surgical drainage of the fistula tract system with the placement of loose setons precedes combined therapy with immunosuppressant and anti-TNFα agents in most patients. Proctitis should be rigorously eliminated where possible. Definitive surgical repair is sometimes possible and diversion or proctectomy are occasionally required. Combined medical and surgical management represents a promising avenue for the future.

What role do bacteria play in persisting fistula formation in idiopathic and Crohn's anal fistula?

AIM: The aetiology of Crohn's disease-related anal fistula remains obscure. Microbiological, genetic and immunological factors are thought to play a role but are not well understood. The microbiota within anal fistula tracts has never been examined using molecular techniques. The present study aimed to characterize the microbiota in the tracts of patients with Crohn's and idiopathic anal fistula. METHOD: Samples from the fistula tract and rectum of patients with Crohn's and idiopathic anal fistula were analysed using fluorescent in situ hybridization, Gram staining and scanning electron microscopy were performed to identify and quantify the bacteria present. RESULTS: Fifty-one patients, including 20 with Crohn's anal fistula, 18 with idiopathic anal fistula and 13 with luminal Crohn's disease and no anal fistula, were recruited. Bacteria were not found in close association with the luminal surface of any of the anal fistula tracts. CONCLUSION: Anal fistula tracts generally do not harbour high levels of mucosa-associated microbiota. Crohn's anal fistulas do not seem to harbour specific bacteria. Alternative explanations for the persistence of anal fistula are needed.

Fistulotomy in the tertiary setting can achieve high rates of fistula cure with an acceptable risk of deterioration in continence.

INTRODUCTION: Surgery is the mainstay of treatment of anal fistulas. Low fistulas are often laid open, but higher fistulas present a more difficult problem. Patient choice centres on a compromise between risk of recurrence and risk of impairment of continence. We aimed to determine the efficacy and safety of fistulotomy at a tertiary referral centre, in particular the additional risk of impairment of continence following fistulotomy of the often recurrent, multiply-operated patients seen. METHODS: Patients undergoing surgery under the senior author (RKSP) for an anal fistula during the study period (2005-2006) were identified, and a thorough review of the patients' clinical records was undertaken. Demographic, fistula anatomy, treatment and follow-up data were obtained. RESULTS: Eighty-four patients underwent either fistulotomy (50), insertion of permanent loose (drainage) seton (28) or EUA with or without drainage of abscess. Mean length of follow up was 11 months (SD 14.22). In the fistulotomy group, we found an overall success rate of 93 %. Secondary extensions were associated with failure to achieve cure (P = 0.008). Nine patients (20 %) suffered deterioration in continence after surgery. A longer time to referral was associated with impaired final continence. In the group referred from a surgeon in secondary care, 91 % of patients were cured, and continence impairment (mostly minor) rose from 32 % at referral to 40 % after surgery. CONCLUSIONS: We have shown that it is safe and reasonable to offer fistulotomy to appropriate patients despite previous surgery and within the tertiary setting. By so doing, a very high rate of healing can be achieved in patients who have previously failed. The additional risk of impairment of continence is around one in five, and in the majority will represent only minor incontinence.