The Effect of Timing of Instillation Therapy on Outcomes and Costs for Patients Receiving Negative Pressure Wound Therapy

Ashley W. Collinsworth, ScD, MPH; Leah P. Griffin, MS


Wounds. 2022;34(11):269-275. 

In This Article

Abstract and Introduction


Introduction: Although NPWTi-d has been associated with improved patient outcomes compared with NPWT alone, questions remain regarding the timing of NPWTi-d initiation.

Objective: This study examined the effect of the timing of NPWTi-d initiation on patient outcomes and costs.

Methods: A retrospective analysis was conducted utilizing a national, all-payer hospital database and included patients who received NPWTi-d in 2019. A matched cohort of 514 patients who received either early (within 1 day of NPWT application) or late (within 2–7 days of NPWT application) NPWTi-d initiation was created using propensity scoring. Differences in clinical outcomes and costs were compared using Wilcoxon rank sum, chi-square, and t tests.

Results: Early NPWTi-d initiation was associated with significantly shorter NPWT duration (7.0 vs. 11.4 days; P <.0001) and inpatient stay (13.4 vs. 16.3 days; P <.0001) compared with late NPWTi-d initiation. Early NPWTi-d initiation was also associated with fewer debridements, OR visits during hospitalization, days until final OR procedure, and wound-related readmissions. Patients with early NPWTi-d initiation had a $10 877 lower mean cost of index admission (P <.0001), which included lower NPWT costs.

Conclusion: Study data suggest that in these patients with wounds, early NPWTi-d initiation helped improve patient outcomes and reduced care costs.


Wounds are a major source of patient morbidity, health care utilization, and costs in the United States.[1] NPWT was introduced over 20 years ago as a way to help improve wound management of both chronic and acute wounds.[1] NPWT is used to remove infectious materials and exudate from wounds and has demonstrated effectiveness in promoting wound healing by stabilizing the wound bed, promoting continuous wound drainage, drawing the wound edges together, and stimulating granulation tissue growth.[2–4] Use of NPWT has been associated with improved patient outcomes including earlier wound closure, reduced OR visits, reduced hospital LOS, fewer dressing changes, and reduced risk of amputation.[5–9]

The introduction of topical wound solution delivery (instillation therapy) in combination with NPWT (ie, NPWTi-d) has provided further benefits to promote wound healing.[1] NPWTi-d provides wound cleansing through the periodic instillation of topical wound solutions directly over the wound bed with a set interval of dwell time followed by removal using negative pressure while the dressing remains in place. NPWTi-d has the added benefit of helping disrupt the bioburden cycle of complex wounds through the repeated cycles of wound cleansing with instillation and removal via negative pressure. Use of NPWTi-d has been associated with statistically significant reductions in wound size and bacterial bioburden[10–13] as well as significant improvement in granulation tissue compared with NPWT.[10,14] NPWTi-d use has been cited as a contributor to a reduction in the number of surgeries needed for debridement.[1,3,9,15,16] Several studies have found NPWTi-d to be associated with fewer OR visits, reduced time to final surgical procedure, shorter hospital LOS, and a higher percentage of closed wounds before discharge compared with NPWT alone.[9,15,17]

Initially used in wounds that did not respond to traditional NPWT or as a last-resort therapy, NPWTi-d has gained traction as an integral part of wound management.[18] Consensus guidelines published in 2020 recommend the use of NPWTi-d as an adjunct therapy along with debridement and systemic antibiotics for a wide variety of acute, chronic, and/or infected wounds, including traumatic, surgical, dehisced, and diabetic wounds as well as venous leg ulcers, pressure ulcers, and full-thickness burns, among other wound types.[18] Although the guidelines state that NPWTi-d should be used within the framework of a clearly defined treatment plan and timetable,[18] there are no specific guidelines concerning when NPWTi-d should be initiated, and questions remain regarding the timing of this therapy.[1]

Kaplan et al[5] found that early initiation of NPWT (on day 1 or day 2 of treatment) resulted in a significant reduction in LOS, treatment days, intensive care unit days, and treatment costs compared with late initiation. Given that NPWTi-d can assist with early removal of exudate and provide wound cleansing that may help reduce bioburden,[18] initiating instillation therapy in a timely fashion should help promote wound healing.[1] It is important that the right therapy be administered at the right time, because complications that necessitate additional treatment (eg, infections) may occur in stalled wounds, resulting in increased LOS and spiraling costs of care.[19] While the timing of NPWTi-d may affect patient outcomes, there is a gap in the literature concerning when to initiate NPWTi-d. The objective of this study was to examine the effect of timing of NPWTi-d initiation on patient outcomes and costs.