The Personalised Antibiotic Duration for Cellulitis (PAD-C) Study

Study Overview
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Brief Summary
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Cellulitis is an increasingly common and unpleasant bacterial infection of the skin, usually affecting the legs. Patients experience pain and swelling, loss of mobility, fever, and chills. Patients may be left with chronic skin damage and 1 in 5 experience recurrences. Cellulitis is treated with antibiotics, but it is unclear as to how long treatment should be for. As a result, many patients get much longer antibiotic treatment than needed. This exposes patients to the risks of taking unnecessary antibiotics. This study aims to find out what features of individual patients predict a good, sustained recovery from cellulitis. These may include medical conditions and clinical response to the first few days of antibiotic treatment, such as changes in skin temperature. Patients who are being treated in hospital for cellulitis will be invited to take part. Information will be collected about patients who will be followed up for 3-6 months. Devices for measuring skin temperature will also be compared to see which one works best. This information will be used to help develop a set of rules that doctors can use to guide the length of antibiotic treatment. This should ensure that future patients receive the amount of antibiotics needed and no more.

Detailed Description
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This study is a single centre prospective cohort study of patients with cellulitis of the lower limb. The primary objective of this study is to understand what features of individual patients predict a sustained recovery from cellulitis. This information will be used to test and refine a previously developed risk score that predicts clinical outcomes of patients with cellulitis. Secondary objectives include investigating whether early response to antibiotic treatment (e.g. reduction in skin temperature and patient-reported symptoms) improves the predictive ability of the risk score. The study design also includes a nested technology comparison of temperature measurement devices to identify the best device for measuring affected skin temperature change in patients with cellulitis. Clinical response will be measured for up to four days from starting antibiotic treatment. This includes the change in temperature and area of affected skin, physiological observations, blood test results (e.g. C-reactive protein) and patient-reported pain and swelling scores. Patients will be followed up at 28 and 90 days (+/- 180 days for those recruited in the first year) to assess recovery, recurrence, cellulitis-related mortality, quality of life, and return to normal activities.

Official Title
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The Personalised Antibiotic Duration for Cellulitis (PAD-C) Cohort Study

Conditions
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Cellulitis, Cellulitis of Leg, Antibiotic Duration

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults (age ≥18 years) identified by their treating clinician as having lower limb cellulitis that requires IV or oral antibiotic treatment either from the hospital or another service based outside of the hospital, which will conduct ongoing follow-up regardless of location. Exclusion Criteria: Patients: who have already received 3 or more calendar days of antibiotics from the hospital for cellulitis. receiving antibiotic therapy for another indication that is anticipated to continue for longer than the antibiotic treatment for cellulitis and that, in the judgement of the investigator, would impact the study assessments. for whom a surgical procedure to treat their cellulitis is planned (i.e. debridement of suspected necrotising skin / soft tissue infection). who, in the judgement of the investigator, do not have a clear diagnosis of cellulitis (to enable the exclusion of infections, such as severe/deep diabetic foot infection, which may be loosely labelled as cellulitis, but treated with different guideline antibiotic agents and durations). lack capacity to give informed consent to participate. are receiving end-of-life care. are already involved in a CTIMP of relevance to the treatment of their cellulitis. are unlikely, in the opinion of the investigator, to comply with study procedures.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Population<br>Adults (age ≥18 years) identified by their treating clinician as having lower limb cellulitis that requires intravenous or oral antibiotic treatment either from the hospital or another service based outside of the hospital, which will conduct ongoing follow-up regardless of location. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sustained recovery | No initiation of new antibiotic treatment for cellulitis at the same site through to 90 days | 90 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Recovery at 28 days | The absence of warmth and tenderness at the site, with improvement in swelling and acute colour change, that did not require new antibiotic treatment | 28 +/- 3 days | 
| Patient-reported time to resolution of cellulitis symptoms | Patient-reported time to resolution of cellulitis and symptoms of pain and swelling, using a numeric and verbal marked scale (1 to 10, higher score indicates higher severity of symptom) | 28 +/- 3 days | 
| Change in quality of life | Change in quality of life assessed using the Medical Outcomes Study Short Form 12-Item Health Survey (SF-12) compared to baseline | Baseline, 90 days (+/- 180 days for a subset recruited within the first year) | 
| Time to return to work / normal activities | Patient-reported date at which they returned to work / normal activities | Baseline, 28 days, 90 days (+/- 180 days for a subset recruited within the first year) | 
| Cellulitis-related readmission | New hospital admissions/reattendance containing a cellulitis diagnostic code | 90 days (+/- 180 days for a subset recruited within the first year) | 
| Cellulitis-related mortality | Death within 90 (+/- 180) days of initial admission/attendance | 90 days (+/- 180 days for a subset recruited within the first year) | 
| Antibiotic usage and antibiotic-related adverse events | Route and duration of antibiotic therapy, adverse events from patient-report, medical and laboratory records | Through study completion, an average of 180 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cellulitis, Antibiotics, Treatment duration, Treatment length