Negative pressure wound therapy for treating foot wounds in people with diabetes mellitus.

Background: Foot wounds in people with diabetes mellitus (DM) are a common and serious global health issue. People with DM are prone to developing foot ulcers and, if these do not heal, they may also undergo foot amputation surgery resulting in postoperative wounds. Negative pressure wound therapy (NPWT) is a technology that is currently used widely in wound care. NPWT involves the application of a wound dressing attached to a vacuum suction machine. A carefully controlled negative pressure (or vacuum) sucks wound and tissue fluid away from the treated area into a canister. A clear and current overview of current evidence is required to facilitate decision-making regarding its use.

Objectives: To assess the effects of negative pressure wound therapy compared with standard care or other therapies in the treatment of foot wounds in people with DM in any care setting.

Search Methods: In January 2018, for this first update of this review, we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies, reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting. We identified six additional studies for inclusion in the review.

Selection Criteria: Published or unpublished randomised controlled trials (RCTs) that evaluated the effects of any brand of NPWT in the treatment of foot wounds in people with DM, irrespective of date or language of publication. Particular effort was made to identify unpublished studies.

Data Collection And Analysis: Two review authors independently performed study selection, risk of bias assessment and data extraction. Initial disagreements were resolved by discussion, or by including a third review author when necessary. We presented and analysed data separately for foot ulcers and postoperative wounds.

Main Results: Eleven RCTs (972 participants) met the inclusion criteria. Study sample sizes ranged from 15 to 341 participants. One study had three arms, which were all included in the review. The remaining 10 studies had two arms. Two studies focused on postamputation wounds and all other studies included foot ulcers in people with DM. Ten studies compared NPWT with dressings; and one study compared NPWT delivered at 75 mmHg with NPWT delivered at 125 mmHg. Our primary outcome measures were the number of wounds healed and time to wound healing.NPWT compared with dressings for postoperative woundsTwo studies (292 participants) compared NPWT with moist wound dressings in postoperative wounds (postamputation wounds). Only one study specified a follow-up time, which was 16 weeks. This study (162 participants) reported an increased number of healed wounds in the NPWT group compared with the dressings group (risk ratio (RR) 1.44, 95% confidence interval (CI) 1.03 to 2.01; low-certainty evidence, downgraded for risk of bias and imprecision). This study also reported that median time to healing was 21 days shorter with NPWT compared with moist dressings (hazard ratio (HR) calculated by review authors 1.91, 95% CI 1.21 to 2.99; low-certainty evidence, downgraded for risk of bias and imprecision). Data from the two studies suggest that it is uncertain whether there is a difference between groups in amputation risk (RR 0.38, 95% CI 0.14 to 1.02; 292 participants; very low-certainty evidence, downgraded once for risk of bias and twice for imprecision).NPWT compared with dressings for foot ulcersThere were eight studies (640 participants) in this analysis and follow-up times varied between studies. Six studies (513 participants) reported the proportion of wounds healed and data could be pooled for five studies. Pooled data (486 participants) suggest that NPWT may increase the number of healed wounds compared with dressings (RR 1.40, 95% CI 1.14 to 1.72; I² = 0%; low-certainty evidence, downgraded once for risk of bias and once for imprecision). Three studies assessed time to healing, but only one study reported usable data. This study reported that NPWT reduced the time to healing compared with dressings (hazard ratio (HR) calculated by review authors 1.82, 95% CI 1.27 to 2.60; 341 participants; low-certainty evidence, downgraded once for risk of bias and once for imprecision).Data from three studies (441 participants) suggest that people allocated to NPWT may be at reduced risk of amputation compared with people allocated to dressings (RR 0.33, 95% CI 0.15 to 0.70; I² = 0%; low-certainty evidence; downgraded once for risk of bias and once for imprecision).Low-pressure compared with high-pressure NPWT for foot ulcersOne study (40 participants) compared NPWT 75 mmHg and NPWT 125 mmHg. Follow-up time was four weeks. There were no data on primary outcomes. There was no clear difference in the number of wounds closed or covered with surgery between groups (RR 0.83, 95% CI 0.47 to 1.47; very low-certainty evidence, downgraded once for risk of bias and twice for serious imprecision) and adverse events (RR 1.50, 95% CI 0.28 to 8.04; very low-certainty evidence, downgraded once for risk of bias and twice for serious imprecision).

Authors' Conclusions: There is low-certainty evidence to suggest that NPWT, when compared with wound dressings, may increase the proportion of wounds healed and reduce the time to healing for postoperative foot wounds and ulcers of the foot in people with DM. For the comparisons of different pressures of NPWT for treating foot ulcers in people with DM, it is uncertain whether there is a difference in the number of wounds closed or covered with surgery, and adverse events. None of the included studies provided evidence on time to closure or coverage surgery, health-related quality of life or cost-effectiveness. The limitations in current RCT evidence suggest that further trials are required to reduce uncertainty around decision-making regarding the use of NPWT to treat foot wounds in people with DM.