Oral aspirin for treating venous leg ulcers.

BACKGROUND: Venous leg ulcers (VLUs) or varicose ulcers are the final stage of chronic venous insufficiency (CVI), and are the most common type of leg ulcer. The development of VLUs on ankles and lower legs can occur spontaneously or after minor trauma. The ulcers are often painful and exudative, healing is often protracted and recurrence is common. This cycle of healing and recurrence has a considerable impact on the health and quality of life of individuals, and healthcare and socioeconomic costs. VLUs are a common and costly problem worldwide; prevalence is estimated to be between 1.65% to 1.74% in the western world and is more common in adults aged 65 years and older. The main treatment for a VLU is a firm compression bandage. Compression assists by reducing venous hypertension, enhancing venous return and reducing peripheral oedema. However, studies show that it only has moderate effects on healing, with up to 50% of VLUs unhealed after two years of compression. Non-adherence may be the principal cause of these poor results, but presence of inflammation in people with CVI may be another factor, so a treatment that suppresses inflammation (healing ulcers more quickly) and reduces the frequency of ulcer recurrence (thereby prolonging time between recurrent episodes) would be an invaluable intervention to complement compression treatments. Oral aspirin may have a significant impact on VLU clinical practice worldwide. Evidence for the effectiveness of aspirin on ulcer healing and recurrence in high quality RCTs is currently lacking.

OBJECTIVES: To assess the benefits and harms of oral aspirin on the healing and recurrence of venous leg ulcers.

SEARCH METHODS: In May 2015 we searched: The Cochrane Wounds Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE and EBSCO CINAHL. Additional searches were made in trial registers and reference lists of relevant publications for published or ongoing trials. There were no language or publication date restrictions.

SELECTION CRITERIA: We included randomised controlled trials (RCTs) that compared oral aspirin with placebo or no drug intervention (in the presence or absence of compression therapy) for treating people with venous leg ulcers. Our main outcomes were time to complete ulcer healing, rate of change in the area of the ulcer, proportion of ulcers healed in the trial period, major bleeding, pain, mortality, adverse events and ulcer recurrence (time for recurrence and proportion of recurrence).

DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies for inclusion, extracted data, assessed the risk of bias of each included trial and assessed overall quality of evidence for the main outcomes in the 'Summary of findings' table.

MAIN RESULTS: The electronic search located 62 studies. We included two RCTs of oral aspirin (300 mg/daily) given in addition to compression compared with compression and placebo, or compression alone. To date, the impact of aspirin on VLUs has been examined by only two randomised clinical trials, both with a small number of participants. The first RCT was conducted in the United Kingdom (n=20) and reported that daily administration of aspirin (300mg) in addition to compression bandages increased both the rate of healing, and the number of participants healed when compared to placebo in addition to compression bandaging over a four month period. Thirty-eight per cent of the participants given aspirin reported complete healing compared with 0% in the placebo group . Improvement (assessed by reduction in wound size) occurred in 52% of the participants taking aspirin compared with 26% in those taking placebo). The study identified potential benefits of taking aspirin as an adjunct to compression but the sample size was small, and neither the mechanism by which aspirin improved healing nor its effects on recurrence were investigated.In 2012 an RCT in Spain (n=51) compared daily administration of aspirin (300mg) in addition to compression bandages with compression alone over a five month period. There was little difference in complete healing rates between groups (21/28 aspirin and 17/23 compression bandages alone) but the average time to healing was shorter (12 weeks in the treated group vs 22 weeks in the compression only group) and the average time for recurrence was longer in the aspirin group (39 days: [SD 6.0] compared with 16.3 days [SD 7.5] in the compression only group). Although this trial provides some limited data about the potential use of aspirin therapy, the sample size (only 20 patients) was too small for us to draw meaningful conclusions. In addition, patients were only followed up for 4 months and no information on placebo was reported.

AUTHORS' CONCLUSIONS: Low quality evidence from two trials indicate that there is currently insufficient evidence for us to draw definitive conclusions about the benefits and harms of oral aspirin on the healing and recurrence of venous leg ulcers. We downgraded the evidence to low quality due to potential selection bias and imprecision due to the small sample size. The small number of participants may have a hidden real benefit, or an increase in harm. Due to the lack of reliable evidence, we are unable to draw conclusions about the benefits and harms of oral daily aspirin as an adjunct to compression in VLU healing or recurrence. Further high quality studies are needed in this area.