Design: Systematic review and meta-analysis of 85 randomised trials
Population: 16,980 adults with primarily closed surgical incisions
Primary outcome: Overall surgical site infection
Effect: RR 0.64 (95% CI 0.57–0.72), NNT 21; blistering RR 4.51 (2.37–8.58), NNH 18

This meta-analysis of 85 randomised trials (16,980 adults) compared incisional negative pressure wound therapy on closed incisions with standard dressings across surgical specialties.

Negative pressure was associated with fewer surgical site infections overall (RR 0.64, 95% CI 0.57 to 0.72), including both superficial and deep, and with less dehiscence, seroma, reoperation and skin necrosis. Organ-space infection, readmission and mortality did not differ. The trade-off was more skin blistering (RR 4.51) and device-related adverse events (RR 11.87). One infection was prevented for every 21 patients treated, while one blister occurred for every 18 and one device problem for every 11. Certainty was moderate.

The balance favours targeting rather than blanket use: high-risk incisions such as those in obesity, diabetes, emergency laparotomy or re-operation, where the infection benefit is likely to be largest. Cost matters too, and in many Indian units the device price will decide.

Consider incisional negative pressure for incisions at high risk of infection, such as obesity, diabetes or emergency laparotomy.
Avoid routine use on low-risk clean incisions; harms were about as frequent as benefits.
Warn patients about skin blistering and check the skin at each dressing review.
Do not expect it to prevent organ-space infection or reduce readmission.
Factor in device cost when setting local criteria.

Why it matters

The benefit is real but so is the harm, which makes patient selection the actual decision.

The statistics, in plain English

A risk ratio of 0.64 means about a third fewer wound infections. A number needed to treat of 21 means 21 patients get the dressing for one infection prevented; a number needed to harm of 18 means one in 18 gets a blister. Benefit and harm are of similar frequency, which is why who you use it on matters.