Abstract: 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. 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.

Plain-language summary: We identified only two randomised controlled trials that compared oral aspirin (300mg daily) plus compression with compression and placebo, or compression alone. One study conducted in UK included 20 participants (ten in the aspirin group and ten in the control group) and followed people for four months. This trial reported that the ulcer area had reduced (by 6.5 cm², a 39.4% reduction) in the aspirin group compared with no reduction in ulcer area in the control group, and that a higher proportion of the ulcers (38%) in the aspirin group had completely healed compared with none in the control group. Recurrence was not investigated in this study. Another study conducted in Spain included 51 participants (23 in the aspirin group and 28 in the control group) and followed people until their ulcers had healed. The study reported that the average time for healing was 12 weeks in the aspirin group and 22 weeks in the control group, and that there was no real difference between the proportion of people with ulcers healed (17 (74%) out 23 people in the aspirin group and 21 (75%) out 28 people in the control group). The average time for recurrence was longer in the aspirin group (39 days) compared with (16.3 days) in group of compression alone. Adverse events were not reported in either trial. We considered these two studies too small and low quality for us to draw definitive conclusions about the benefits and harms of oral aspirin on the healing and recurrence of venous leg ulcers. The UK study provides only limited data about the potential benefits of daily oral aspirin therapy with compression due to a small sample size of only 20 participants and short follow up. The Spanish study provides limited data on 51 participants comparing aspirin and compression to a control group. The fact that no information was reported regarding placebo in the control group means the estimate of effect is uncertain. Further high quality studies are needed in this area. This plain language summary is up to date as of 27 May 2015.