Is Noncontact Normothermic Wound Therapy Cost Effective for the Treatment of Stages 3 and 4 Pressure Ulcers?

Author(s): 
Alex Macario, MD, MBA;1 Franklin Dexter, MD, PhD2

This is greater than the 45-percent healing rate at six months measured among patients with pressure ulcers at VA long-term care facilities.57 Rates of healing reported in that study are derived from administrative data and, as such, are likely to be underestimates of the true healing rate, which may explain why our model had a greater six-month healing rate. The underestimation may arise as patients whose ulcers healed and who then developed new pressure ulcers were considered not healed. Also, many patients had more than one ulcer and were not counted as healed unless all of their pressure ulcers had healed. Third, healing of pressure ulcers in patients that were discharged was not included. That study also found that 31 percent of patients with stage 4 ulcers would be healed at six months. In another study, a national nursing home chain similarly reported a 40-percent healing rate for stage 3 pressure ulcers and a 34-percent healing rate for stage 4.58 Both of these rates are within a few percentage points of what our model predicts.

     3. Our model predicts that the mean length of treatment for a stage 3 ulcer receiving standard care, from initial occurrence to complete healing, will equal 153 days. This is consistent with a wound closure rate of 0.1cm2/day as documented by Ferrell59 for a 16cm2 wound (as per our base case). Also, a study of long-term care patients with pressure ulcers found mean treatment length to equal 116 days.60

     Advanced wound care products compete with one another and with other medical treatments for reimbursement from federal and commercial payers. Thus, we also completed a second literature search to compare the efficacy of NNWT to topical negative pressure, another advanced wound care product.61 We found one prospective trial with a total of 24 participants that evaluated the effectiveness of topical negative pressure on 36 chronic wounds.62 However, this study did not report statistical analyses, and healing data for the subset of patients who had pressure ulcers was not reported. Additional well-controlled, blinded, “head-to-head” clinical trials, as well as studies of the use of NNWT in nonresearch protocol settings, are necessary.

     In our modeling, we assumed that transition probabilities from one health state to another remained constant as time went on (e.g., probability of healing after the first eight-week time period was equal to the probability of healing in the fourth eight-week time period). However, it may be that the efficacy of both standard and NNWT treatments decreases as a pressure ulcer ages. We simulated decreasing efficacy of both treatments as the pressure ulcer aged and found no significant impact on overall results.

     Costs, outcomes, and benefits can be analyzed from different points of view—the patient, the provider, the payer, or society as a whole.63 For example, the cost of a medical service to the payer (insurance company) equals the percentage of charges actually paid by the payer. However, the relevant cost to the patient is the out-of-pocket expense (not covered by insurance) plus other costs (e.g., inability to work) incurred due to illness. A different way to assign a cost for nursing services may have impacted the cost model. For example, from the facility’s perspective, nursing care time may be considered a fixed cost, as staff are paid regardless of whether there is one more or one less pressure ulcer to treat. However, we assumed that having a provider take care of a pressure ulcer is an incremental cost to society, as is commonly done in cost-effectiveness studies, to reflect that from society’s point of view, there is a cost for the provider’s time and expertise.

     Our computer simulation study has several limitations.

References: 

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