Wound Care Outcomes and Associated Cost Among Patients Treated in US Outpatient Wound Centers

Data From the US Wound Registry

Caroline E. Fife, MD, CWS; Marissa J. Carter, PhD, MA; David Walker, CHT; Brett Thomson, BS

Disclosures

Wounds. 2012;24(1) 

In This Article

Discussion

These data confirm previous studies demonstrating that chronic wound patients have multiple comorbidities that would have excluded them from RCTs. While they are likely to heal with the interventions available, the "cost to heal" a chronic wound increases as the number of comorbid conditions increases. Not all wounds achieve healing and nonhealing wounds are among the most expensive. Among nonhealing patients for whom 3 or more years of data are available, the cost of care continues to increase in a near linear fashion, and the costs associated with nonhealing wounds would seem to be a significant savings opportunity. After some point, additional expenditures in patients with nonhealing wounds do not seem to produce measurable benefit but there may be cost savings, which are not visible (eg, hospitalizations which are prevented). While "palliative care" was an option as a "goal of therapy," fewer than 3% of patients were designated as palliative. Thus, it seems likely that some of the patients followed over long time frames (eg, more than a year) were actually receiving palliative care even though they were not designated as such. Further analysis of these data is warranted to determine how limited resources can be best directed. Diagnosis related groups (DRGs) effectively "capped" the cost of inpatient care by limiting reimbursement based on the number and severity of diagnoses. In contrast, the "fee for service" model of outpatient care has continued to reward both physicians and hospitals for performing high cost, advanced therapeutics without a feedback mechanism for quality or outcomes of care. This appears to be the intent of proposed programs such as "accountable care organizations," but the mechanism by which reimbursement will be linked to quality and outcomes is not clear.

Limitations

This study suffers from the usual limitations of retrospective data analysis, as well as limitations regarding certain cost factors. These data are affected by the quality of clinical documentation. Thus, lack of thorough documentation would affect our estimations of prevalence of comorbid disease as well as certain treatment interventions. The inability of the ICD-9 coding system to identify wounds unusual etiologies, or in some cases correctly assign even common ulcer types to the correct category is a serious limitation. For example, there is no ICD-9 code for a "diabetic foot ulcer," these ulcers are identified by linking "chronic ulcer" to the underlying diagnosis of diabetes. The same is true for arterial ulcers. In addition to the lack of specific ICD-9 codes for most wounds and ulcers, in some cases, even the most experienced clinician may be challenged to correctly classify a wound/ulcer when multiple etiologies may apply (eg, a heel ulcer in a patient with severe arterial disease and diabetes). There is an extreme lack of functionality of the ICD-9 coding system (not improved with the upcoming ICD-10) in classifying wounds and ulcers. These shortcomings may indirectly affect quality of care (making it difficult to standardize treatment protocols if diagnosis coding is confusing) and poses serious impediments to wound healing research. In addition, in our desire to assess longitudinal care, and the exclusion of patients with certain missing data fields may have skewed our dataset towards patients who received advanced therapeutics. Evaluating a multiyear picture of care may account for what appears to be a relatively high percentage of patients who received modalities such as NPWT and HBOT. Furthermore, practice trends may change over a 5-year time frame (clinicians might increase or decrease utilization of advanced therapeutics over several years).

While we had access to actual cost and charge data, our calculations represent underestimations of real costs. The method by which negative pressure wound therapy and home nursing are actually charged to the payer is not on a per diem basis but in 30- or 90-day cycles. We estimated costs based on daily rates over the time of known use based on physician orders, likely underestimating by a significant margin since charges to the payer are usually rounded up to the next 30 days. Our lack of access to the costs associated with diagnostic or laboratory testing is another area of underestimation.

One advantage of using this particular EHR for data collection is that since the EHR automatically abstracts the chart to calculate charges, and charges determine both the clinic and physician revenue, all clinicians are highly incentivized to perform thorough documentation. The use of EHR data has some other advantages in this setting. Because all the medical data are collected for each patient, it is possible to analyze any aspect of care, as opposed to a "metrics of interest" method for most prospective registries. Because the data are derived from the medical chart and all the charts contribute automatically to the registry, 100% of the patients seen at the clinic become part of the registry. Thus, there is no selection bias in patient enrollment. Registries that require separate data entry may discourage the enrollment of patients with large numbers of wounds or complex histories. De-identified EHRs also guarantee clinician participation. Since the clinicians must do their medical charting anyway, the data needed for the registry are collected at the same time the medical record is created. This provides access to a broad cross-section of practice types, without regard to individual physician or facility motivation for research or quality measures.

It is likely that the quality of care varies highly from one facility to another. However, the point of this study was to determine outcome and costs in the "real world" setting, and since variations in quality of care are drivers of cost, it was not necessary to control for this factor. However, quality of care likely does affect outcome. For this reason, outcome measures such as "healing rates" would seem to be poor quality of care indicators. We have demonstrated that many, if not most chronic wound patients have serious comorbid conditions, which might negatively impact healing. One could argue that the most skilled centers would become referral points for the most complex patients, eventually decreasing their healing rates (unless risk adjusted) rather than increasing them. Thus, better measures of "quality" in the wound care industry would seem to be process measures such as diabetic foot off-loading, venous ulcer compression, or vascular screening. Quality measures like these might help standardize practice and facilitate future pooled data analysis.

Despite the limitations of these data, registries created from pooled, de-identified EHRs may represent a way to determine the real world effectiveness of wound care treatments once efficacy has been established in RCTs. However, true "comparative effectiveness" studies of the expensive modalities used among chronic wound patients will require a method to stratify patients by severity of illness.

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