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Early Versus Late Initiation of Negative Pressure Wound Therapy: Examining the Impact on Home Care Length of Stay
Because of the high cost of some wound management regimens, payors may require that moist wound therapies be used before other treatment approaches, such as negative pressure wound therapy (NPWT), are implemented but few studies have investigated the effect of delayed initiation of NPWT on patient outcomes.
To examine the impact of early versus late initiation of NPWT on patient length of stay in home health care, a nonrandomized, retrospective analysis was performed on the Outcome and Assessment Information Set (OASIS) information for home care patients with NPWT-treated Stage III or Stage IV pressure ulcers (N = 98) or surgical wounds (N = 464) gathered between July 2002 and September 2004. Early initiation of NPWT following the start of home care was defined as <30 days for pressure ulcers and <7 days for surgical wound patients. Median duration of NPWT was 31 days (range 3 to 169) for pressure ulcers and 27 days (range 5 to 119) for the surgical wound group. Median lengths of stay in the early treatment groups were 85 days (range 11 to 239) for pressure ulcers and 57 days (range 7 to 119) for the surgical group versus 166 days (range 60 to 657) and 87 days (range 31 to 328), respectively, for the late treatment pressure ulcer and surgical groups (P <0.0001). After controlling demographic patient variables, regression analysis indicated that for each day NPWT initiation was delayed, almost 1 day was added to the total length of stay (β = 0.96, P <0.0001 [pressure ulcers]; β = 0.97, P <0.0001 [surgical wounds]). Early initiation of NPWT may be associated with shorter length of stay for patients receiving home care for Stage III or Stage IV pressure ulcers or surgical wounds. Additional studies to ascertain the cost-effectiveness of treatments and treatment approaches in home care patients are needed.
In 2005, the US Centers for Medicare and Medicaid Services (CMS) identified chronic wounds as an important issue for long-term examination.1 Chronic wounds such as pressure ulcers (PUs)2 typically are difficult to heal and often result in longer lengths of stay (LOS) than acute wounds, requiring more skilled nursing visits and more wound care supplies, each of which drives costs for treatment higher.3
In 1988, $8.4 billion was spent on home care services in the US.4,5 By the end of 2008, the CMS estimates that the cost of home care services will exceed $62.6 billion.4,5 This seven-fold increase in expenditures over the past two decades has prompted the CMS to 
make fundamental changes in how home health agencies (HHAs) are reimbursed and to institute broad quality improvement initiatives.6
In 2004, 60.5% of patients served by HHAs in the US presented with wounds or lesions at the start of care.7 Inconsistent wound assessment and documentation of advanced wound therapy utilization have been cited as protracting healing and necessitating more frequent nursing visits, resulting in additional costs.8
The cost of negative pressure wound therapy (NPWT) as well as other advanced wound therapies can be high; therefore, many private payors have adopted Medicare’s NPWT coverage policy requiring moist wound therapies be used, considered, or ruled out before reimbursing for NPWT.9 Yet, few studies have investigated whether the initiation of NPWT early in a patient’s LOS is associated with a decrease in the overall LOS.10 As a result, a nonrandomized, retrospective analysis of an Outcome and Information Set (OASIS) database was conducted to examine whether early initiation of NPWT could influence overall LOS in home care patients with a Stage III or Stage IV PU or a surgical wound.
Methods
Database and therapy. A nonrandomized, retrospective analysis of the Outcome Assessment and Information Set (OASIS) database from patient data gathered between July 2002 and September 2004 was performed to identify patients with a prior Stage III or Stage IV PU or a surgical wound treated with NPWT. The OASIS database is a standard national assessment tool designed to enable a rigorous and systematic measurement of patient home health care outcomes between two or more points in time. The OASIS data items address socio-demographic, environmental, support system, health status, functional status, and health service utilization characteristics of the patient. Data are collected at start of care, at recertification of care (every 60 days), at resumption of care if the patient required hospitalization, and at discharge.
OCS, Incorporated (Seattle, Wash) is a benchmarking company that maintains the largest OASIS database outside of the CMS. This proprietary database contains data from approximately 13 million individual records, representing five million complete cases of home care. Negative pressure wound therapy was defined as the use of vacuum-assisted closure (V.A.C.® Therapy, Kinetic Concepts, Inc, San Antonio, Tex).
OCS matched the company providing the NPWT devices to HHA customers with their client agencies to identify agencies who had utilized NPWT. Using a unique set of identifiers, NPWT patients with a Stage III or Stage IV PU or a surgical wound were identified with NPWT start and stop dates. Patients treated with NPWT early in their LOS were compared to patients treated with NPWT late in their LOS. All patient data were de-identified as required by HIPAA.
Inclusion/exclusion criteria. All OASIS patient records were examined to determine whether they met the inclusion and exclusion criteria (see Table 1). Inclusion criteria were selected to enhance the homogeneity of the study population; exclusion criteria 
were selected to reduce potential confounding by compromised nutritional status, risk factors, or other comorbidities that could seriously compromise the patient’s prognosis. Demographic information, comorbidity, length of NPWT, and length of home care services data were recorded for each patient.
Establishing subgroups. Pressure ulcer patients were subdivided based on early versus late initiation of NPWT. Early initiation was defined as NPWT initiation within the first 30 days of HHA start of care. Late initiation was defined as NPWT initiation after the first 30 days of HHA start of care. In the PU group, 30 days was chosen as the point of division based on the Medicare NPWT policy that provides that other dressings providing a moist wound environment be tried, considered, and/or ruled out before ordering NPWT.
Patients with a surgical wound also were subdivided based on early versus late initiation of NPWT. Early initiation for the surgical group was defined as NPWT initiation within the first 7 days of HHA start of care; late initiation was defined as NPWT initiation after the first 7 days of HHA start of care. The rationale was based on the growing practice of utilizing NPWT as a first line therapy while the patient is still in the hospital or within the first few days of HHA start of care. Moreover, the data demonstrated a natural division between patients who had NPWT initiated within the first 7 days of HHA start of care verses those who had NPWT started after the first 7 days of HHA start of care.
Data analysis. Overall LOS was compared between the early and late subgroups for each wound type. Results were expressed as percentages for categorical variables and median and range for continuous variables. In both the PU and surgical groups, a multiple linear regression model was constructed to estimate the relationship of time to initiate NPWT and home care LOS after controlling for age, obesity, gender, PU stage, coronary artery disease, hypertension, impaired mobility, peripheral vascular disease, diabetes, and connective tissue disease.
Microsoft Excel, SQL, Access, and SPSS (SPSS Inc., Chicago, Ill) software packages were utilized throughout the study to facilitate data imports, merges, and calculations. T-tests were used to determine statistical significance of between-group comparisons. Significance was determined at P <0.05 for all tests.
Results
Ninety-eight Stage III or Stage IV PUs and 464 surgical wound patients met the inclusion criteria for the study. Mean patient ages were 61.8 years (SD 21.6) for PU and 63.8 years (SD 16.0) for surgical wounds. Demographic and comorbidity comparisons of the groups are listed in Table 2 and Table 3.
Pressure ulcer patients. Ninety-eight pressure ulcer patients were evaluated (n = 65 early initiation, n = 33 late initiation). The mean age (SD) of PU patients was 64.47 years <
(±21.41) for early initiation of NPWT and 56.45 years (±21.3) for late initiation. The median age of PU patients was 68 years for early and 52.42 years for late initiation. The mean (SD number of days between home care admission and start of NPWT was 5.49 days (±8.14) in the early and 129.42 days (±125.27) days in the late initiation group. Median length of stay for the early group was 85 days (range 11 to 239) versus 166 days (range 60 to 657) for the late group (P <0.0001). With respect to LOS in terms of episodes of care (1 to 60 days = one episode of care; 61 to 120 days = two episodes, and so on), the median number of treatment episodes required was two (range one to four) in the early group versus three (range one to 11) in the late group (P <0.0001). Forty-two percent of patients in the early group were discharged from home care during their first episode versus 3% in the late group (P <0.0001). Interestingly, the median duration of NPWT while in home care was 31 days for both the early and late PU groups. Regression analysis indicated a parameter estimate of 0.96. In other words, for each day NPWT use was delayed, 1 day was added to the total LOS (β = 0.96, P <0.0001). This estimate was controlled for all variables considered.
Surgical wounds. Of the 464 patients with a surgical wound, 352 received early and 112 had late initiation of NPWT. The mean age for surgical patients was 63.24 years (±16.16) for early initiation of NPWT and 65.70 years (±15.47) for late initiation; median ages for early and late NPWT initiation in these groups were 67 and 69.7, respectively. The p-values below are from a two-sample t-test comparing the averages ages of the two groups. The mean number of days before NPWT was initiated (from home care admission) in the early versus late surgical wound group was 0.13 (±2.12) and 38.96 (±43.44) days, respectively (in some cases, therapy was initiated in acute care before patients were admitted to home care). Of the 464 patients, the 341 (73.5%) who were discharged from the hospital were more likely to begin NPWT within 7 days of the start of their home care than patients who had not been admitted to the hospital before starting home care (75.9% versus 66.1%, P = 0.0491).
Median LOS for the early surgical wound group was 57 days (range 7 to 119) versus 87 days (range 5 to 328) for the late surgical wound group (P <0.0001). With respect to LOS in terms of episodes, the median number of treatment episodes required was one (range one to five) in the early group versus two (range one to six) in the late group (P <0.0001). Patients were almost twice as likely to be discharged during the first 60-day episode of 
care (62.8% versus 34.8%, P <0.0001). The median duration of NPWT was 27 days.
The regression analysis found a parameter estimate of 0.97; for each day NPWT use was delayed, 0.97 days was added to the total LOS (β = 0.97, P <0.0001). This estimate was controlled for all variables considered.
Discussion
The results of this study demonstrate a parallel scenario related to both PU and surgical wounds, suggesting that a relationship exists between earlier use of NPWT and reduced overall LOS. The regression analysis shows that for each day the initiation of NPWT was delayed, almost one day was added to the home care LOS. For a PU patient, an average of 10 days would be added to the overall LOS. This would require the HHA to clinically and financially support the care of that patient for an additional 9 or 10 days, respectively. For a surgical wound, if a patient receives NPWT on day 11 of HHA service instead of day 1, an average of 9 days can expected to be added to the overall LOS.
A limitation of this study is that the OASIS extracted data did not detail other wound care modalities used before, after, or in tandem with NPWT. In addition, the etiology of surgical wounds is not available within the OASIS database and other factors that may have contributed to healing, such as nutritional maximization and pressure redistribution in the case of pressure ulcers, also were not noted in the data. These factors, coupled with the noncontrolled, nonpowered retrospective study design, may result in bias of the study results.
The CMS has been focused on developing outcome measures in home care since OASIS inception. In 2000, the Medicare Prospective Payment System (PPS) was established, paying HHAs a predetermined base payment rate per patient, per 60-day episode of care. In fact, under the new 2008 PPS rule, two new mandatory wound-related performance measures gleaned from OASIS must be publicly reported on Home Health Compare (part of the PPS rule): 1) emergent care for wound infections or deteriorating wound status; and 2) improvement in status of surgical wound. In the future, it is reasonable to assume more performance measures will be developed along with mandatory reporting requirements.
Continued financial pressures under the new PPS changes coupled with additional reporting mandates will force agencies to better understand the relationship between the delivery of high quality care and cost. Home health agencies will need to gain even greater efficiencies in the way they manage wound care, as well as in their understanding and quantification of what wound care therapies are most cost-effective. Agencies that understand the relationship between cost and outcomes will be better prepared to succeed under the imminent pay-for-performance structure.
It has been previously reported that the utilization of NPWT compared to other wound therapies on patients with a Stage III or Stage IV PU and surgical wounds may reduce the incidence of emergent care and hospitalization. In 2005, Schwien et al10 reported in a retrospective study of OASIS start-of-care assessments in 2003 and 2004, that the utilization of NPWT compared to other wound therapies on patients with a Stage III or Stage IV PU reduced emergent care instances and hospitalization due to wound infection or wound deterioration. Joseph et al11 conducted a prospective, randomized controlled trial of 24 enrolled patients with 36 nonhealing wounds and concluded that NPWT should be used to obtain wound closure, especially for chronic nonhealing wounds with great depth, instead of traditional saline wet-to-moist dressings. Kaplan et al12 retrospectively analyzed 1,518 patient records of complex traumatic wounds and reported that early use of NPWT (within 2 days of admission) significantly reduced LOS (P <0.0001), treatment days (P = 0.0498), and ICU stay (P <0.0001), which resulted in significantly reduced patient treatment costs (P <0.0001). This evidence, along with the present study, suggests that the relationship between NPWT and overall LOS may be particularly attractive to the home health industry under the cost/quality-based PPS system.13
Conclusion
A retrospective study of the OASIS database with regard to time of implementation of NPWT has shown that earlier initiation of therapy (within 7 days of home health care admission) may reduce LOS in certain HHA patients. In addition to improving healthcare outcomes (ie, time to healing), earlier rather than later implementation of NPWT may reduce unnecessary utilization of services and home care LOS. An economic evaluation from a prospective clinical study may be needed to confirm the cost effectiveness of NPWT in the home care setting.
Dr. Baharestani is Associate Professor, East Tennessee State University, Center for Nursing Research; and Wound Specialist/Education and Research, James H. Quillen Veterans Affairs Medical Center, Johnson City, Tenn. Ms. Houliston-Otto and Dr. Barnes are Manager and Senior Biostatistician, respectively, Health Economics. Please address correspondence to: Mona M. Baharestani, PhD, ANP, CWON, CWS, East Tennessee State University, Center for Nursing Research, Roy Nicks Hall, Office 1-112, Johnson City, TN 37614; email: baharest@etsu.edu.
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