The Wound Trend Scale: A Retrospective Review of Utility and Predictive Value in the Assessment and Documentation of Lower Leg Ulcers
Wound assessment is essential to manage wound care. The Wound Trend Scale (WTS) is a paper-and-pen instrument comprised of 14 parameters designed to guide assessment of findings relevant to lower leg ulcer management and includes an infection screen and cues for physician consultation. To determine its clinical utility, predictive value, and reliability, data were retrospectively analyzed from a random sampling of medical records of patients seen at a Foot and Leg Clinic between January 1, 2007 and December 31, 2008.
Patients had 1 leg or foot ulcer, 3 consecutive assessments scheduled according to wound status (twice weekly if at high risk for nonhealing or amputation, weekly for moderate risk, or 1 to 2 months if stable), known outcomes, and a maximum treatment period of 3 months. Patient demographics included ulcer etiology, comorbid conditions (diabetes, neuropathy, peripheral arterial disease), and wound outcomes (closed, infection, amputation and surgery). Predictive values, inter- and intrarater reliability (assessed among the authors and 5 additional nurses with expertise using the study instrument), and the impact of WTS education on the wound assessment process were determined using 5 representative cases. Parameters were compared using the t-test. Seventy (70) patient records were examined and subdivided by ulcer site: foot (below ankle, 37) and leg (ankle and above, 33). Of the 13 etiologies, the foot group had 4 and the leg group 10; the foot group had more diabetes (92%), neuropathy (76%), and peripheral arterial disease (95%) than the leg group (52%, 5%, and 70%, respectively). Ulcer duration before referral averaged 16.42 (range 4–144) months. Wound outcomes included closed (57), infection (21), amputation (13), and surgery (3). Healing predictive values were sensitivity (99%), specificity (87%), and positive and negative predictive values and test efficiency (all 96%). Inter- and intrarater reliability were .85 (range .16–.96) and .86 (range .50–1.00), respectively. On admission, leg ulcers had larger surface area (P <0.05), more edema (P <0.01), more granulation (P <0.05), and higher total WTS scores (P <0.05) than foot ulcers, which had more infections (P <0.05). Foot ulcers at the third assessment had decreased tissue depth (P <0.05), increased epithelial tissue (P <0.01), and lower total WTS score (P <0.05). Significant third assessment parameters for leg ulcers were reduced depth (P <0.001), less necrotic tissue (P <0.001), less exudate (P <0.01), improved periwound condition (P <0.05), reduced edema (P <0.001), and increased epithelialization (P <0.01). After exposure to the WTS experience, the number of parameters assessed increased from 2.6 (registered nurses) and 1.5 (student nurses) to both using 15 (P <0.001). Nurses complied 100% with physician consultation for cued risks. Patient outcomes were 81% closure, and 70% had physician consultation for the risks identified. WTS predictive performance was excellent and improved nursing assessment practices. Future research to identify parameter criteria validity is warranted.
A chronic leg ulcer, defined as “any skin damage below the knee that takes more than 4 to 6 weeks to heal,”1 simplifies the classification of ulcers but fails to alert the clinician to the importance of identifying etiological and comorbid factors essential to optimal care. An Australian epidemiology study2 (N = 242) classified chronic leg ulcer etiologies by diagnosis and comorbid disease influences, singly or in combination. The etiologies identified were venous insufficiency, mixed etiology, arterial disease, diabetes, rheumatoid arthritis, thrombocythemia, trauma, skin tumor, chronic osteomyelitis, pyoderma gangrenosum, chronic dermatitis, chronic infected sinus, and Martorell ulcer. Additional types of leg ulcers identified through the authors’ clinical experience are neuropathic ulcers, surgical wound failure, pressure ulcers, vasculitis, deep vein thrombosis, calciphylaxis, burns, lymphedema, lipedema, self-mutilation, septic shock, emboli, Kaposi sarcoma, factor S ulcer, Marjolin’s ulcer, and foot deformity-related ulcers, which can be congenital or secondary to comorbid diseases such as diabetes.
The multiple etiologies of leg ulcers, combined with individual patient comorbidities and available resources of different clinical care environments, underscore the considerable challenges of their clinical management. Implementation of a periodic nursing questionnaire (1994, 1998, 2004, and 2005) that audited wound care in Sweden enabled longitudinal analysis of prevalence, etiology, treatment of hard-to-heal leg and foot ulcers, and nursing time.3,4 From 1994 to 2005, wound management improved, ulcer prevalence declined from .22% to .15%, weekly treatment time dropped from 1.7 to 1.3 hours per patient, and annual costs decreased by $6.96 million SEK. Repeated questionnaires, ongoing education, development of a wound healing center, and creation of multidisciplinary wound management recommendations all served to increase interest in and effectiveness of wound management.
A descriptive survey5 of a sample of district nurses in Norway regarding their opinions of their knowledge of foot and leg ulcer treatment (N = 102 completed questionnaires) found most nurses (60%) felt they had inadequate knowledge of wound care. They were uncertain about assessment, etiology, choice of wound healing products, and treatment. Individual clinical experience and colleagues were the main sources of their knowledge of wound care.
A descriptive observational study6 that analyzed 35 ulcer treatments provided to 32 patients with foot and leg ulcers by 31 home care nurses in Norway found no etiologic ulcer diagnosis was made in 16 cases and serious comorbidities were present in 79.9% of cases. Overall, nurses in this study were unsure of their assessment, treatment principles used often were outdated, documentation of treatment was poor, and use of compression on undiagnosed ulcers was sometimes incorrect.
An incidental sampling survey7 of podiatrists and nurses in the United Kingdom (N = 102) attending a lower extremity wounds conference explored attitudes, knowledge, and skill in lower extremity wound care to identify training needs and inform wound care education. The majority of respondents participated in continuing professional development, whereas the minority used accredited university courses. Inconsistencies in wound care knowledge and skills that were identified highlighted the importance of educational strategies to standardize wound care.
Wound assessment is fundamental to diagnosis, appropriate care, and monitoring wound progress, but the aforementioned research5,7 has found professional training programs for primary care nurses lack sufficient clinical education to provide appropriate care for patients with leg ulcers. A wound assessment tool that provides a common clinical language and encourages consultation could bridge gaps in professional knowledge between primary and specialist care providers.
Foot and Leg Ulcer Clinic. The Foot and Leg Ulcer Clinic in Victoria, British Columbia, Canada is a referral facility for patients with problematic wounds (ie, nonhealing, deteriorating, necrotic tissue, amputation risk, or other clinical problems). The core clinic team consists of 2 advanced wound care nurses and 2 physicians. Nurses admit and monitor patients in collaboration with a physiatrist who follows medical care, and a foot and ankle orthopedic surgeon evaluates and follows patients who may require surgery and postoperative care. A network of disciplines that provides expedited referral access includes vascular surgeons, infectious disease specialists, orthotists, podiatrists, pedorthists, and compression garment fitters. Consultations with physiotherapy, occupational therapy, dietetics, and social services are available on an individual basis. The nurses coordinate wound management with the primary nurses through care plans, consultation, and education.
Wound Trend Scale (WTS). The WTS, a paper-and-pen instrument developed by clinic wound speciality nurses, evolved through evaluation and modifications to improve relevance to leg ulcers and utility in a working clinic. Wound assessment theory is melded with clinical information to identify findings that are sensitive to wound healing phases, wound bed preparation, and risk identification.
The WTS systematically guides assessment of findings relevant to leg ulcer management, current wound status, significance of findings, wound trend, wound needs, and changes in the wound using 14 parameters, an infection screen, and cues for physician consultation. Each parameter has identified findings that are assigned a value from low to high corresponding to its potential to impair healing. The nurse examines the wound for each parameter and records the value of the highest finding identified (if absent, the item is left blank on the form). A decrease in value from the previous assessment is interpreted as a positive change that may predict healing or reduce impairment to healing. Increased values indicate deterioration or possibly more impairment to healing. The total WTS score is the combination of influences each parameter contributes. Healing is predicted when the total score is equal to or less than the previous total (closure, defined as complete epithelialization, is 0); an increase in the total score predicts wound deterioration. Infection risk screening is performed at every assessment. High risk of amputation, nonhealing findings, and positive infection screens are cued with an asterisk and require the nurse to consult with a physician. Assessments are recorded on the WTS documentation form and stored in the medical record.
At the authors’ clinic, patient reviews are scheduled according to wound status: twice weekly for high risk, weekly for moderate risk, or 1 to 2 months if stable. Primary care nurses or family physicians are encouraged to communicate concerns.
WTS parameter rationale and use. The WTS documentation form uses a unique number identification for each wound starting with 1, which is recorded on the care plan with the start and end dates recorded as day, month, and year (eg, #1 Left posterior heel, Start 010512, Closure 060712; #2 Left 5th toe, Start 220210, Amputation 060610). Multiple columns allow the identification number of wounds, assessment dates, and values for findings for each wound to be recorded. Wound closure or surgical procedures are recorded as end dates.
A retrospective analysis8 of 2350 heel pressure ulcers used data from the United States Wound Registry and regression models to assess factors known to be associated with healing. The analysis identified depth of tissue involved as a significant variable (P <0.05), which then was tested and validated. Variables predicting healing likelihood in nearly all pressure ulcer assessment models were wound size, wound age, number of wounds, evidence of bioburden, tissue type exposed (Wagner grade or stage), nonambulatory status, and need for hospitalization during treatment. The analysis resulted in a wound stratification system and healing index that could predict healing likelihood. With the exception of nonambulatory status and hospitalization, all of these variables are included in the WTS.
A study by Greatrex-White and Moxey9 to evaluate the ability of existing wound assessment tools to meet the needs of nurses performing wound assessment included a literature review that identified criteria of an optimal wound assessment tool. Assessment tools, which were selected using specified inclusion and exclusion criteria, then were evaluated against the optimal criteria. No evaluated tool fulfilled all criteria. The WTS addresses objective wound findings (measurement, tissue type, exudate, surrounding skin, pain and infection) and advanced subjective issues (documentation, communication, and ease of use). Greatrex-White and Moxey’s study elevates the role of wound assessment tools to support nursing practice, a practical issue for the clinic where regular nursing staff are wound specialist nurses and relief staff are not. The ultimate goal is to provide a wound assessment tool that supports both nonwound specialist nurses and specialist nurses to assess wounds systematically and consistently consult with the physician when cued risks are identified.
Surface area. Surface area is the maximum wound length multiplied by the perpendicular maximum width to the nearest 0.5 cm (a simple way to achieve this is by visualizing a square around the wound). Reduction in surface area is associated with healing, but an increase may indicate tissue loss from infection, ischemia, trauma, pressure injury, factitious injury, nonhealing, or debridement of necrotic tissue.
A review10 of the importance of wound measurement found both serial area measurement and percentage area reduction can differentiate responding from nonresponding wounds and help predict outcomes. A reduction over 2 to 4 weeks in wound area predicts healing or advises a reassessment of treatment was demonstrated in a multicenter, randomized controlled trial11 of 90 venous leg ulcers that found the 2-week percentage reduction in wound area was correlated with outcome (P = 0.002) — that is, a >30% reduction by 2 weeks is an accurate predictor of healing.
Depth. The type of tissue (injured, dead, or lost) influences the risk of amputation or nonhealing of leg ulcers. Depth value is the highest finding identified: partial-thickness or full-thickness skin loss; involvement of fascia, muscle, tendon, or bone; presence of a foreign body or medical devices; or obscure when all of the wound base cannot be seen. Anatomic knowledge of the ulcer site, including the location of blood vessels and nerves, is necessary to anticipate findings and identify if probing could be a risk. Patient consent is required before gently examining the wound base with a sterile probe to identify the type and integrity of involved tissues; clinic care standard does not allow probing wounds if the patient cannot cooperate, is at anatomical risk, the procedure causes pain, or if pathergy is known or suspected.
The anatomic structure of the foot and of the leg to a lesser extent limits the clinical significance of depth measurements, because much of the foot and parts of the leg have shallow tissue coverage of tendons and bones. As a result, injury to toes, metatarsal heads, heels, ankles, and the tibia crest may be limb-threatening but appear insignificant. A high-risk cue is assigned to tendon, capsule, bone, foreign body, medical device, or obscure.
Edge. Edge classifications include indistinct; distinct and attached; rolled and detached; or fibrotic, scar, or callus. Ousey and McIntosh12 acknowledge reduced vascularity, elasticity, and strength (about 70%) of scar tissue, compared with original tissue, may contribute to delayed healing and a fragile epithelial surface.
Undermining. Undermining, or tissue loss under the skin or between tissue planes, may present as a sinus, fistula, or abscess. The extent of undermining may be estimated by probing the undermined area and marking the end of the probe detected on the skin surface; the value recorded is the maximum length identified in cm. The amount of wound edge undermined is valued as 1: <25%, 2: 25%–50%; 3: 51%–75%; and 4: >76%.
Necrotic tissue and debridement. Debridement of necrotic tissue, such as slough and soft and hard eschar, reduces bioburden and odor, accelerates the inflammatory healing phase, and stimulates quiescent wounds.13 Selection of debridement method depends on the nature and amount of necrotic tissue, patient status, and presence of infection.
Stable eschar is dry, hard, nonfluctuant, and not infected. In cases of suspected arterial insufficiency, guidelines14 recommend stable eschar be kept dry and intact until vascular investigation of the healing potential of the wound is completed and the physician is consulted regarding debridement method.
To provide a full description of the wound base, the WTS assigns values to the percentage of necrotic and risk tissues identified in depth: 1: <25%; 2: 26%–50%; 3: 51%–75%; and 4: >76%.
Exudate. Exudate is identified by type and amount based on dressing presentation: 1) moist — exudate present, nonadherent dressing; 2) small — exudate present to saturated dressing with contained exudate; 3) moderate — exudate strikethrough; 4) large — leaking exudate onto clothing; or 5) uncontrolled — exudate leaking onto the patient, clothing, and/or bed linen within 48 hours of dressing change or dry when moist healing is desired. The need to rehydrate tissues delays healing dry wounds that require a moist environment.
Bleeding is not an expected finding for chronic wounds; the cause should be investigated. Active bleeding requires physician consultation. The surgeon is notified of serosanguineous or purulent drainage from a previously closed incision, which is an indication of surgical wound failure.
The World Union of Wound Healing Societies consensus document15 states the amount of exudate is influenced by the size of the wound and healing phase, with the maximum amount during the inflammatory and proliferative phases and with reduction to 0 with complete epithelialization. Increased exudate is associated with factors that increase capillary leakage such as cardiac, renal, or hepatic failure; edema; inflammation; increased bacterial burden; impaired lymphatic drainage; and specific wound pathology. Exudate color and viscosity are influenced by the type of necrotic tissue present, bacterial colonization, white blood cell presence, and the dressing material used. Managing exudate depends on diagnosing and treating underlying conditions and appropriate dressing selection. Figure 1 illustrates the importance of cleansing the wound before attempting to identify the type of exudate and differentiate pus from accumulated drainage.
Periwound skin. Periwound skin is examined to identify blanchable and nonblanchable erythema, maceration, tissue breakdown, trauma, or rash. Erythema can be a sign of inflammation or infection, but nonblanchable erythema indicates altered blood flow and impending tissue destruction. An exploratory study16 comparing blood flow in areas of nonblanchable erythema to undamaged skin found high perfusion in the center of the lesion and normal perfusion in unaffected areas. In her clinical review, Bianchi17 identified maceration associated with exudate enzymes increases the risk of tissue breakdown and dressing trauma. Rashes and periwound breakdown are investigated for venous eczema, autoimmune disorders, cellulitis, and contact dermatitis.18,19
Appropriate management of periwound skin includes effective cleansing. A Cochrane review20 found no evidence to suggest the use of potable tap water to cleanse wounds and the periwound skin influences infection or wound healing in acute or chronic wounds, including those with bone exposure. Showering loosens necrotic tissue and removes periwound surface debris, organisms, and exudate. In addition, a retrospective analysis21 of cleansing methods for chronic foot and leg ulcers (N = 236) found showering may lower the rate of both toe and major amputations compared with the use of foot baths (P = 0.037). Cooled boiled water, distilled water, or saline solution may be used for chronic wounds when potable water is not available.
Edema. The practice of scoring pitting edema as 1+ (2 mm), 2+ (4 mm), 3+ (6 mm), and 4+ (8 mm)22 may be unsuitable for many leg ulcers because fibrosis and shallow tissue depth may not allow sufficient tissue expansion from fluid pressure. To overcome these issues, the authors developed an edema scale (see Figure 2).
Edema has been reported to contribute to ulcer development, delayed healing, cellulitis,23 amputation risk,24 and surgical wound dehiscence.25 A prospective study24 of 575 patients with an infected diabetic foot ulcer found periwound edema was an independent risk factor for amputation, which was necessary in 159 patients (28%).
In her clinical review of managing chronic edema, Hedger26 points to the multiple local and systemic causes that require the correct etiologic diagnosis to determine appropriate management. A Cochrane review27 of compression for venous ulcers found compression increased wound healing rates compared with no compression.
Pain assessment. On admission to the authors’ clinic, comorbidities and age-associated changes that contribute to the patient’s pain experience, singly or in combination, are investigated. Patient perception of pain (presence or absence) is embedded in the infection screening. Nurses must be alert to the possibility of loss of protective sensation due to neuropathy or progression of arterial insufficiency and that infection may trigger a different sensation (eg, ache where sensation previously was absent).
Infection risk. Every assessment includes infection screening; if positive, physician consultation is required. Infected chronic wounds may increase size, undermining, or exudate amount.28 The classic signs and symptoms of infection are erythema, warmth, swelling, and pain. The Infectious Diseases Society of America’s29 clinical practice guideline for the diagnosis and treatment of diabetic foot infections requires the presence of ≥2 classic signs of infection for diagnosis of infection. Patients with diabetes may have elevated blood glucose when the ulcer is infected.
At the authors’ clinic, wound cultures are done if signs and symptoms of infection are evident. According to Dow,28 chronic wound response to infection may be subtle and require differentiation from tissue breakdown due to inadequate pressure offloading or insufficient perfusion. Biofilm is a potential source of infection, which may be controlled with maintenance debridement and topical antiseptics.13
A 2-year longitudinal cohort study30 compared the accuracy of a diagnosis of osteomyelitis in patients with diabetic wounds (N = 247) using the probe-to-bone (PTB) test and bone culture. During a mean 27.2-month follow-up, 30 patients were diagnosed with osteomyelitis. Overall, the PTB test was both highly sensitive (0.87) and highly specific (0.91). Although the negative predictive value was 0.98, the positive predictive value was only 0.57, indicating the PTB test may be better at ruling out osteomyelitis than at confirming it.
An observational study31 comparing the University of Texas (grade and stage) and Wagner (grade) ulcer classification systems as predictors of outcome in 194 patients with diabetic foot ulcers found increasing ulcer stage (which includes presence of infection) was associated with delayed healing and increased amputation risk.
The purpose of this clinical experience study was to describe lower leg ulcers and analyze wound assessment and associated clinical management data using the WTS. Specific wound assessment tool functions are examined in the following questions:
• What is the predictive performance of the WTS for wound healing or deterioration?
• What is the inter- and intrarater reliability of the WTS for clinic nurses experienced in using the WTS to assess leg ulcers?
• Can the identification or change in WTS findings be used to select or evaluate interventions and monitor response?
• What is the compliance with physician consultation when an asterisk-cued, high-risk finding or positive infection screen is identified?
The study data were derived from information contained in the medical records of a random, retrospective convenience sample of 70 patients seen at the authors’ clinic between January 1, 2007 and December 31, 2008. Inclusion criteria stipulated patients had 1 leg ulcer (wound below the knee), 3 consecutive WTS assessments, known wound outcomes, and treatment within a maximum of 3 months. The number of patients was an arbitrary decision by the Wound Collaborative Committee. Patient data were reviewed and analyzed in total as well as by subgroups by ulcer site (foot, below the ankle; and leg, ankle and above) to represent wound groups such as diabetic foot ulcers or venous leg ulcers.2 The clinical specialist and nursing staff extracted patient and ulcer data, including all WTS parameter findings, from the medical records and entered it into Microsoft Excel spreadsheets.
Patient and ulcer description. Patient records were reviewed for ulcer etiology, distribution of ulcers by site as foot (below the ankle) or leg (ankle and above), and duration of ulcer before clinic referral; outcomes included closure (complete epithelial coverage), infection, surgical procedures other than amputation, and amputation (major, below or above knee; or minor, limb preservation involving digits, rays, and the ability to stand or walk32).
Predictive value performance for wound healing. Nursing staff collected data from 3 consecutive WTS assessments, including positive infection screen information and ulcer outcome, on a spreadsheet. The total WTS scores were compared: the second score was compared to the first and the third to the second. Equal or reduced scores identified the prediction as positive for healing. Increased scores identified the prediction as negative for healing (ie, deterioration). Each author independently reviewed the patient information from the medical record to verify the prediction; differences were settled by consensus. Standard formulas for calculating sensitivity, specificity, predictive values (positive and negative, including false values for each), and test efficiency were used to determine predictive value performance.
Consent and ethics approval. Clinic patients routinely provide consent for treatment and use of their clinical data for clinical, educational, or research purposes. Patients were also routinely consulted and agreed to treatment throughout their care process. As a result, the Research Ethics Committee in Victoria, BC, determined ethics approval was not required for performing the clinical experience study. Nurses participated in the study on a volunteer basis and were assured of anonymity.
Inter- and intrarater reliability. Collecting inter- and intrarater reliability information with patients was deemed unacceptable because patients would be subject to multiple wound assessments that could increase waiting time for treatment and pain and decrease access to other clinic patient services. An alternative was to develop 5 cases based on typical assessment requirements and common clinical presentations. The Certified Wound Specialist (author) developed the cases. Each case had a wound image and a written description of etiology, relevant history, and findings not accessible from the image (eg, warmth, pain). The cases were reviewed by a second author and trialed by the third before rater reliability was assessed.
Information on the cases used to determine interrater reliability was emailed to volunteer clinic nurses with WTS experience (N = 5) to be completed at their convenience. A second email requested a repeat assessment for intrarater reliability 24 hours after electronic receipt of completed assessments. Participating nurse anonymity was ensured by assigning the nurses numbers and labeling the case sets as A or B for interrater reliability and intrarater reliability, respectively. Parameter findings, WTS scores, and positive infection screens were compared to the Certified Wound Specialist’s assessment for interrater reliability and the nurses’ first and second case sets for intrarater reliability. Correlation coefficients (median and range) were calculated using the Microsoft Excel 2010 statistic program.
Change in wound assessment practice. Community registered nurses (N =10) and student nurses (N = 10) volunteered to participate while attending a clinic observation day. Before any wound management discussion, each participant demonstrated his or her wound assessment process on a consenting patient while an author checked assessment parameters observed on a WTS form. Then the lead author provided a 15-minute WTS education session, after which the participant practiced assessment using the WTS form with coaching by an author. Each participant then completed a solo wound assessment using the WTS, during which the author recorded the wound assessment parameters used. The number of wound parameters assessed by each volunteer, including infection screen, was compared for the pre- and post-WTS education wound assessments.
WTS influence on selection, monitoring, and evaluation of wound interventions. Parameter findings, infection screen, and admission total WTS score were compared for the subgroups (foot and leg) to identify differences in ulcer characteristics. The same factors were compared to identify sensitivity of the WTS to response to wound management between admission (first assessment) and the third assessment for the subgroups. The medical record was reviewed to match the parameter findings with the selection of appropriate wound intervention or compliance with care guidelines. Parameter findings associated with amputation and infection were reviewed to identify a common cluster.
Physician consultation for cued risks and positive infection screens. The number of tissue depth findings and positive infection screens that cued physician consultation was confirmed by reviewing the medical records; compliance was the percentage of confirmed consults.
Statistical analysis. Determination of true or false predictions provided values for the number of true positives, false positives, true negatives, and false negatives. Standard equations were used to calculate predictive performance of the WTS (sensitivity, specificity, positive and negative predictive values, and test efficiency). Assessment of the inter- and intrarater reliability among WTS-experienced volunteer nurses was performed by calculating the Pearson product-moment correlation coefficient (r) using Microsoft Excel 2010. Change in assessment practice was analyzed with the 2-sample, 2-tailed, unpaired t-test assuming unequal variances in Microsoft Excel 2010. Analysis of WTS parameter findings, including positive infection screens and total score for the group and subgroups by wound site, used an unpaired, 2-sample, 2-tailed t-test assuming equal variances using Microsoft Excel 2010.
Ulcer etiology and description. The 70 records examined included 37 foot and 33 leg ulcers. Average ulcer duration was 16.42 (range 4–14) months before clinic referral. Table 1 itemizes the primary ulcer etiology and comorbidities based on wound site. Foot wounds had fewer etiologies: 65% were diabetic foot ulcers, 22% were heel ulcers, 8% were related to trauma, and 5% to surgical hardware. Leg wounds included 10 different etiologies: 48% were arterial/venous mixed ulcers, 12% were related to trauma, 9% each involved venous insufficiency and pyoderma gangrenosum, 6% were related to vein harvest, and 1 case each (3%) to malignancy; hematoma; scleroderma; calcinosis, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and elangiectasia (ie, CREST syndrome); and rheumatoid ulcer. Comorbid conditions (diabetes, 92%; neuropathy, 76%, and peripheral arterial disease, 95%) occurred more frequently in foot than leg ulcers (52%, 15%, and 70%, respectively).
Ulcer outcomes. Fifty-seven (57, 81%) wounds closed, 12 at the third assessment and 45 later. Of the 21 positive infection screens, 15 were in the foot and 6 in the leg. Thirteen (13) amputations (8 foot, 5 leg; all major) were performed. The 3 surgeries that were required all occurred in the foot group; 2 involved removal of surgical hardware closed post surgery, and 1 was a debridement that exposed extensive tissue loss requiring a major amputation.
Predictive value performance. The predictive value of the WTS included sensitivity (99%), specificity (87%), positive predictive value (96%), negative predictive value (96%), and test efficiency (96%). Table 2 presents completed WTS wound assessment data to demonstrate use of the form and real case illustrations of scores for true positive, false negative, and true negative classification. Table 3 provides the distribution of true positives, false positives, true negatives, and false negatives along with the equations and predictive value calculations. Figure 3 provides images and scenario information of the cases A, B, and C as documented in Table 2.
Inter- and interrater reliability. The average Pearson correlation coefficient (r) for interrater reliability was .85 (range .16–.96), and the average Pearson correlation coefficient for intrarater reliability was .86 (range .50–1). One nurse missed surface area and tissue depth for 1 case, which appeared to be an oversight because all other cases submitted by this nurse included these parameters.
Change in wound assessment practice. Registered nurses used significantly more wound assessment parameters (2.6) than student nurses (1.5) before WTS education and experience (P <0.001). The number of WTS parameters and infection screenings increased to 15 for both registered and student nurse groups (P <0.001) after WTS training and experience (see Table 4).
WTS parameter influence or response to wound management. On admission, 45% of patients had necrotic tissue. Debridement is standard practice but not clearly reported in the medical record. Maggot debridement therapy was identified for 11 patients; after 1 week of maggot debridement therapy, necrotic tissue was removed with the following outcomes: exposure of surgical hardware (1 case), extensive tissue loss requiring amputation (1), and closure (9); closure of the wounds after surgical removal of hardware was included for the entire group. Edema was identified in 38 patients on admission and successfully reduced with appropriate compression therapy for 14 patients. Two (2) patients with a dry wound bed were provided a semiocclusive dressing to hydrate the wounds.
Parameters infrequently identified were undermining (15, 21%) and induration (9, 13%), but the nurses responded to these findings with physician consultation resulting in diagnosis and more frequent assessments to monitor progress or detect complications. Of the 15 patients with undermining, 12 required major amputations. Patients with induration had different etiologies or outcomes: diagnosis of inflammatory ulcer (4), trauma (3), and amputation (2).
Infection was identified by culture in 21 wounds (15 foot and 6 leg). Antibiotic therapy was prescribed after physician consultation for all patients. Among the 16 patients with ulcers containing persistent necrotic tissue, a positive infection screen was accompanied by a medical intervention (antibiotics, surgical debridement, monitoring plan). Outcomes for these patients included 11 amputations, 1 surgical hardware removal, and 4 closures.
All patients undergoing amputation (13) had the following findings: total WTS score increased or was 1 point lower, tendon and/or bone tissue involvement was noted, and no epithelial tissue was identified.
Significant differences were found between foot and leg ulcers on admission. Leg ulcers had a larger surface area (P <0.05), more edema (P <0.01), more granulation (P <0.05), and higher total scores (P <0.05) than foot ulcers. Foot ulcers had more infections (P <0.05). No significant difference in healing (defined as complete epithelialization) was noted. Table 5 provides complete data for this comparison.
Parameter changes between admission and the third assessment were examined to determine sensitivity of parameters to change during treatment of foot and leg ulcers. Patients with foot ulcers had a significant decrease in tissue depth (P <0.05), increased epithelial tissue (P <0.01), and a lower total score (P <0.05); these outcomes are expected with foot ulcer healing progression when appropriate wound care and offloading are provided. The foot group had 24 (65%) diabetic foot ulcers and 8 (22%) heel ulcers; when combined, 87% of the patients had pressure offloading as standard practice. Significant parameter changes identified for the leg ulcer site group were decreased depth (P <0.001), less necrotic tissue (P <0.001), less exudate (P <0.01), improved periwound (P <0.05), reduced edema (P <0.001), and increased epithelialization (P <0.01). The leg group had more edema (P <0.01); evidence-based practice supports the use of compression for venous ulcer treatment.24 If arterial/venous mixed and venous insufficiency patients are combined, 19 (57%) of the leg ulcers could potentially benefit from compression therapy. Reduced pressure gradient compression was used effectively for 14 patients, resulting in a significant edema parameter change (P <0.001), which may reflect parameter sensitivity to compression therapy. Compression therapy ulcer healing exhibited typical findings: decreased depth, necrotic tissue, and exudate and improved periwound condition.
Physician consultation for cued risks and positive infection screens. Nurses consulted physicians when encountering a cued, high-risk, or positive infection screen in 87 instances (65 tissue depth, 22 positive infection screens) with 100% physician consultation with interventions documented in the medical record; 49 (70%) of the patients had been identified as being at high risk.
Predictive value of the WTS to leg ulcer healing or deterioration was high for sensitivity (99%), specificity (87%), positive predictive value (96%), negative predictive value (96%), and test efficiency (96%). These results are encouraging because they represent a real working specialist wound clinic and patient population when ulcers are treated regardless of potential to heal.
Another leg ulcer assessment tool is the Leg Ulcer Measurement Tool (LUMT), developed by Woodbury et al.33 In their study, 22 patients with leg ulcers (arterial, venous, diabetic) were assessed by 4 specialist wound nurses and 2 inexperienced nurses over 4 months to determine rater reliability. Responsiveness of the total LUMT score was based on 1-rater assessments of 19 patients (3 did not complete the study). The researchers reported interrater and intrarater reliability >0.75 for total LUMT score and responsiveness to wound status coefficient = 0.84.
A major difference between the LUMT and WTS is the surface area score and its implication to the total score and interpretation of the findings. Both instruments calculate the surface area as the maximum length multiplied by width in cm2, but the WTS assigns the parameter value of the surface area where the LUMT assigns the surface area to unequal interval categories (ie, 1: >2.5 cm2, 2: 2.5–5 cm2, 3: 5.1–10 cm2, and 4: >10.1 cm2). To illustrate the difference in parameter sensitivity and clinical interpretation of this difference, an ulcer with 3 consecutive assessments surface area of 1 cm x 2 cm, 1 cm x 1 cm, and 0.5 cm x 0.5 cm would all be scored 1 and interpreted as no change in the LUMT, but the WTS would assign a parameter value of 2, 1, and 0.25 and interpret the change as a healing trend. The same wound surface area in reverse would be interpreted in the WTS as deterioration but remains as 1 and no change in the LUMT. The largest surface area in the current study was 22 cm x 11 cm, a WTS value of 242 WTS and a LUMT of 4. Ranking findings from least to most potential to impair wound healing to determine parameter value would give maceration a score of 3 (WTS) but it is assigned 1 (LUMT).
Greatrex-White and Moxey9 identified a role for wound assessment tools to assist nurses, wound specialists or general, in their everyday practice. The change in the number of assessment parameters from an average of 2.6 parameters for community nurses and 1.5 parameters for students to 15 parameters for both after WTS education and clinical practice (P <0.001) supports the need for both novice and experienced wound nurses to be consistent and reduce dependence on clinical/colleague experience or misinformed memory.
WTS findings or changes with intervention selection supported by medical record review were identified and described but lacked statistical support. Statistical differences in parameters between foot and leg site ulcers and response to therapy (per parameters) were noted between admission and the third assessment for both the foot and leg subgroups. WTS parameters identified for all 13 amputation patients was a total score increase or minimal 1 point improvement, tendon or bone involved, and failure to develop detectable epithelial tissue. These changes can be explained partially by expectations of standard practice but require more rigorous study design and statistical analysis to support these assumptions.
Cued findings and risks that require physician consultation for prompt intervention, diagnosis, or specific care directions may address the low rates of consultation identified by McIntosh and Ousey7 and improve communication between nurses and physicians. Infection screening and embedded pain inquiry ensured clinical assessment and appropriate intervention for patients with a positive infection screen result.
Evaluation of the WTS resulted in revising the WTS (version 3) to cue undermining and induration for physician consultation because these findings were found to be present for ulcers of unusual etiology or indicate risk of amputation.
The duration of leg ulcers before referral to the clinic ranged between 4 months and 12 years. The delay in referral may increase the frequency of complications, nonhealing, and amputations. A specialist clinic may have a referral bias toward more complex or nonhealable wounds. The focus of the clinical experience and predictive value study was limited to the clinic operational needs and resources. Small sample size and lack of statistical analysis consultation support and design may have weakened parameter analysis. The dependence on documentation in this study may underestimate confirmation of an intervention or response to a finding if not recorded or missed by the auditor.
The WTS tool for wound assessment and documentation demonstrated the potential to predict the wound trend for healing and deterioration for leg ulcers. Inter- and intrarater reliability was good for wound nurses with WTS clinical experience. The number of wound parameters assessed by general registered nurses and students during a single day wound clinic experience improved. Further research to determine parameter criteria validity and potential as surrogate endpoints for wound research specific to a parameter (ie, debriding agent efficacy) may be warranted. n
The authors thank the clinic team and patients who consented to have their photographs and experiences made available for educational and research purposes. Editorial support was provided by Joanna Gorski of Prescriptum Health Care Communications Inc, Niagara-on-the-Lake, Ontario, Canada.
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Potential Conflicts of Interest: none disclosed
Ms. N. Campbell was the founder; Ms. D. Campbell was the Nurse Leader (Retired); and Ms. A Turner is a staff Registered Nurse, Foot and Leg Ulcer Clinic, Vancouver Island Health Authority, British Columbia, Canada. Please address correspondence to: Andrea Turner, RN, BSN, HClSc, GNC(c); email: firstname.lastname@example.org