The efficacy and costs of compression therapy to prevent recurrent lower limb cellulitis in adults with chronic oedema

  • Elizabeth Webb

    Student thesis: Doctoral Thesis

    Abstract

    Cellulitis is a common bacterial infection of the skin and subcutaneous tissue, which usually occurs in the legs. It is often recurrent, with up to 47% of patients experiencing one or more repeat episodes within three years. Cellulitis is potentially serious, resulting in morbidity and financial burden for the patient, as well as substantial costs to the healthcare system. It is the third most common reason to present at an emergency department within Australia, with the infection often developing on the background of unmanaged risk factors such as tinea, wounds and oedema. Chronic oedema refers to swelling which has persisted for three or more months. It is a strong risk factor for initial and recurrent cellulitis infections, and the relationship between chronic oedema and cellulitis is cyclical. Expert consensus recommends chronic oedema is managed using compression therapy to prevent recurrent cellulitis infections, however there is little research and no randomised trials to support this theory. Therefore, this project sets out to investigate the efficacy of compression therapy to prevent lower limb recurrent cellulitis in adults with chronic oedema. Additionally, the costs of compression therapy and cellulitis are calculated and compared to assess the cost-effectiveness of the intervention. Studies 1 and 2 comprise the protocol and outcomes of a randomised controlled trial (RCT) which assessed the efficacy of compression therapy to prevent recurrent cellulitis. The single centre, randomised trial with cross-over planned to include 162 adults with lower limb chronic oedema and a history of two or more episodes of cellulitis in the same leg in the two years prior to trial referral. Randomisation was stratified based on prophylactic antibiotic use. Concealed allocation was used to assign participants in a 1:1 ratio to receive lower limb compression therapy and education on cellulitis prevention (experimental group) or the education alone (control group). Follow-up of participants was planned to occur 6-monthly for up to three-years or until 45 episodes of cellulitis occurred across the trial cohort. An interim analysis was planned to occur after the 23rd episode of cellulitis, with prespecified stopping rules agreed on. Following an episode of cellulitis, participants in the control group were crossed over to the experimental group to receive compression therapy. Neither the assessors or patients were blinded for logistical and ethical reasons. Survival analysis was used to assess the primary outcome of time to the first episode of cellulitis. Other secondary outcomes included the impact of compression therapy on cellulitis-related hospital admissions, leg volume and quality of life. During the trial, a total of 183 participants were screened, and 84 were enrolled, with 41 participants being assigned to the experimental group and 43 to the control group. Following the 23rd episode of cellulitis, the interim analysis was conducted by an external statistician. A log-rank test showed a highly significant (pStudy three is a cost-analysis which was conducted during the RCT to measure and compare the cost of compression therapy and cellulitis from both patient and health service perspectives. A clinical audit and patient survey were used to measure patient and health service resource use for (1) compression therapy over 18-months and (2) the most recent episode of cellulitis. Australian reference costs were applied to the measured resources to calculate mean compression therapy and cellulitis costs and, subsequently, the mean total expenditure across both the experimental and control groups during the RCT. Of the 84 RCT participants, the survey and audit were completed for 40 participants on resource use for compression therapy and 43 participants on resource use for cellulitis. The mean cost of compression therapy over 18 months per participant was $421 from a patient perspective and $1905 from a health service perspective. For an episode of cellulitis, the mean cost of a hospitalised and nonhospitalised infection was $4496 and $1320 from a patient perspective and $9071 and $506 from a health service perspective. Across the duration of the RCT, the mean annual cost per participant was $4,972 in the experimental group, compared to $26,382 in the control group. Therefore, the provision of compression therapy produced an annual cost saving of $21,483 (95% confidence interval, $3,136 to 48,176) per participant. This is the first RCT and cost-analysis to demonstrate that for patients with lower limb chronic oedema and recurrent cellulitis, compression therapy is not only efficacious in preventing cellulitis, it is also costsaving. The implications for these patients are clear: oedema management using compression therapy should become standard practice for the prevention of recurrent cellulitis. The health and financial benefits demonstrated by this research provide strong justification for health services and policy makers to advocate for, and invest in, oedema management services for these patients.
    Date of Award2022
    Original languageEnglish
    SupervisorBernie Bissett (Supervisor) & Elisabeth Preston (Supervisor)

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