Title: The impact of postoperative Packing of Perianal Abscess Cavities: a multicentre randomised controlled trial (PPAC2)
Funder: Department of Health and Social Care

Abstract: Background: Perianal abscess is common, affecting 18000 people annually in England. Current management is surgical incision and drainage of the abscess followed by wound packing until the cavity has healed. Packing is thought to reduce the rate of recurrent abscess and perianal fistula; a known complication of perianal abscess. Perianal fistula frequently requires multiple operations to resolve. Management has remained largely unchanged for over 50-years. The evidence for postoperative packing is limited and may expose patients to painful procedures with no clinical benefit and at considerable increased cost. Previous small studies suggest that there may be no benefit to packing in terms of wound healing and fistula rates2,3. Our multicentre observational study (Muliticentre observational study of outcomes after acute perianal abscess [Packing of Perianal Abscess Cavities [PPAC]) found that packing is painful, costly, and patients reported a need an alternative treatment1. There is a clear need for a definitive RCT comparing packing and non-packing of the perianal abscess cavity. Aims: We propose an RCT to assess whether there are differences between non-packing and packing of the perianal abscess cavity in terms of the short term negative effects of packing (pain which was flagged by the PPAC patient focus group as a key outcome, quality of life, return to work) whilst assessing the impact on other key outcomes raised by patients and health professionals: wound healing, fistulae formation (a recognised complication of perianal abscess), resource use/costs and health-related quality of life. Plan of investigation: Adult patients with acute primary perianal abscess will be recruited and randomised 1:1, following incision and drainage operation, to either current standard treatment of continued wound packing until the cavity has healed, or to self-administered non-adherent wound dressings. Patients with perianal abscess associated with Crohns disease, trauma, fourniers gangrene or a horseshoe (bilateral) abscess will be excluded. Operative findings and demographic data will be gathered. Patients will complete a daily diary up to day 5, then on day 7, 14 and 21. The diary contains a 100m Visual Analogue Score (VAS) of pain: worst pain, pain before, during and after dressing change; an EQol5D score; return to work or normal activity; and open-ended questions about the experience of treatment. Patients will be reviewed in the clinic at 4 weeks and 8 weeks to assess would healing, fistula formation or abscess recurrence. If the wound has healed at 4 weeks, the 8-week appointment will be a telephone consultation. Patients will be reviewed at 6 months to assess for fistula formation or abscess recurrence. Hospital Episode Statistic (HES) data and a review of hospital records at 12 months will investigate again for fistula formation and abscess recurrence. The primary end point is pain intensity measured as mean of worst daily pain (wound related) over the first 5 days. Secondary endpoints include abscess and fistula rates, quality of life, cost and return to normal activity. Sample size is 526 based on detecting a clinically relevant 20% reduction in pain intensity between the 2 study arms with 90% statistical power and a two-sided alpha level of 0.05. The study will run for 36 months. Feasibility (site set-up, patient recruitment and retention, data collection tools) has been be demonstrated by our PPAC study1. Potential benefits to patients and the NHS: We hypothesise that non-packing will be significantly less painful than packing, and will not be associated with increased complications. Patients will have better, simpler aftercare with fewer nurse contacts. This proposed research will provide robust evidence, and may change practice for 18000 patients in England each year. This could result in a saving of approximately &pound;5 million for the NHS each year.

Lay abstract: A perianal abscess is an infection close to the back passage (anus). It occurs in more than 18,000 UK patients every year. Standard treatment is a small operation under general anaesthetic when an opening is made in the abscess to let out (drain) the infection. The usual treatment is then to place a dressing into the wound (called packing). The wound pack is changed every one to two days. Packing has traditionally been used as it is thought to aid healing. We know packing wounds is painful and a small study has suggested that packing may not help wound healing. We are conducting a study (Packing of Perianal Abscess Cavities, PPAC2) on patients after drainage of a perianal abscess. This will answer the question whether simple dressings on the wound surface are better than traditional packing into the wound. We will assess patients' discomfort after surgery, time taken to return to normal activities and how patients quality of life is affected. We will also check that the new treatment (simple dressings rather than packing) does not increase the risk of complications from the abscess. We will check healing rates and recurrent infections in each patient. Patients will be invited to participate in PPAC2 after abscess drainage. A computer will randomly assign patients (like tossing a coin) to the new treatment of simple wound dressings or the traditional treatment (wound packing). Patients will keep a diary of dressing or packing changes, discomfort they feel after leaving hospital and return to normal activities. Patients will be seen in clinic to check healing. Results will be shared by publication in medical journals, feedback to doctors, community nurses and organisations such as National Institute Clinical Evidence. The team undertaking the study is composed of experts with a track record of research in this field.

Research activity codes: 6.4 SURGERY
Health categories: ORAL AND GASTROINTESTINAL