Design: Systematic review and meta-analysis of randomised trials
Population: 85 trials, 16,980 adults with closed surgical incisions
Primary outcome: Overall surgical site infection
Effect: RR 0.64 (95% CI 0.57 to 0.72); NNT 21; blistering RR 4.51 (95% CI 2.37 to 8.58)

A systematic review and meta-analysis pooled 85 randomised trials in 16,980 adults comparing incisional negative pressure wound therapy on closed incisions with standard dressings, searching to March 2026.

Negative pressure dressings were associated with fewer surgical site infections overall (RR 0.64, 95% CI 0.57 to 0.72), with similar reductions in superficial and deep infection, dehiscence, seroma and skin necrosis, and slightly fewer reoperations. Organ-space infection, readmission and mortality did not differ. Skin blistering was about four and a half times more common and device-related adverse events about twelve times more common. The number needed to treat to prevent one infection was 21, while the number needed to harm was 18 for blistering and 11 for device problems. Certainty was graded moderate.

The authors argue for selective rather than routine use. Cost matters in Indian practice, where these devices are expensive, so targeting them at high-risk wounds is the realistic approach.

Consider incisional negative pressure dressings for closed wounds at high risk: obesity, diabetes, contaminated cases, long laparotomies or previous wound breakdown.
Do not expect it to prevent deep organ-space infection.
Check the skin under the device for blistering and tell patients what to report.
Keep the basics in place: timely antibiotic prophylaxis, glucose control and normothermia.

Why it matters

Each prevented infection costs about 21 devices and comes with extra blisters, which makes targeting the right patients the real decision.

The statistics, in plain English

A risk ratio of 0.64 means about a third fewer infections, and the interval is narrow and well below 1. Number needed to treat 21 means 21 patients get the dressing to spare one infection; number needed to harm 18 means one extra patient blisters for every 18 treated. Benefit and harm are of similar frequency but very different seriousness.