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Evidence Corner
Chronic Wounds and Delayed Healing Risk
June 2010
Dear Readers:
Forewarned is forearmed. Knowing a chronic wound is at risk of being delayed or nonhealing helps wound care providers improve healing outcomes.1 Knowing and helping patients address risk factors for delayed or nonhealing wounds can also help define the limits of patient risk, patient, caregiver, and provider responsibility, and legal liability.
Below are some surprising and some familiar risk factors for delayed and nonhealing wounds. If you recognize any of these risk factors in a patient, consider what you might do to optimize the patient and wound outcomes: Check causes of tissue damage? Change to a more effective treatment? Refer to a specialist?
Recognizing Venous Ulcers at Healing Risk Reference: Milic DJ, Zivic SS, Bogdanovic DC, Karanovic ND, Golubovic ZV. Risk factors related to the failure of venous leg ulcers to heal with compression treatment. J Vasc Surg. 2009;49(5):1242–1247. Rationale: Venous ulcer (VU) healing rates range from 40%–95% with compression. Factors predicting compromised VU healing include longer ulcer duration; larger surface area; more than 50% of the ulcer surface covered with fibrin, and an Ankle/Brachial Systolic Blood Pressure Index (ABI) of Objective: An open, prospective, single-center study determined risk factors associated with healing delay and nonhealing of VUs treated with a multilayer high compression bandaging system for 52 weeks. Methods: For 189 subjects with a VU at least 5 cm2 in area and 3 months in duration, factors were explored as predictors of either delayed or nonhealing during 52 weeks of treatment with multilayer high compression bandaging. Venous ulcer factors that were studied included surface area, coverage with > 50% fibrin slough, depth > 2 cm, history of surgical wound debridement, and time since ulcer onset. Patient factors that were tested included gender, age, history of deep vein thrombosis or surgery, body mass index (BMI), calf circumference reduction during the first 50 days of treatment, daily walking distance, calf/ankle circumference ratio Results: During 52 weeks of appropriate compression, 87.3% of the chronic VUs healed. Healing was predicted by ulcer duration 2, and during the first 50 days of treatment, new epithelium on > 10% of ulcer surface and/or a decrease in calf circumference > 3 cm. Predictors of delayed VU healing were initial ulcer depth > 2 cm, patient BMI > 33 kg/m2, walking P Authors’ Conclusions: Failure of VUs to heal during 1 year of treatment with multilayer high compression is associated with failure to resolve lower limb edema related to impaired calf muscle pump function.
Predicting Diabetic Foot Ulcer Healing Reference: Snyder RJ, Cardinal M, Dauphinee DM, Stavosky J. A post-hoc analysis of reduction in diabetic foot ulcer size at 4 weeks as a predictor of healing by 12 weeks. Ostomy Wound Manage. 2010;56(3):44–50. Rationale: Four-week percent area reduction has been suggested to distinguish diabetic foot ulcers (DFUs) that will heal in 12 weeks from those that will not heal. Objective: Determine whether a 50% area reduction during weeks 1–4 of standard wound care was associated with closure of large or small DFUs after 12 weeks of treatment. Methods: A post-hoc analysis identified healing predictors in 250 subjects with Type 1 or 2 diabetes and a full-thickness plantar or heel DFU. All subjects completed 12 weeks of standard control treatment with gauze and offloading in two randomized controlled trials of a dermal substitute conducted in 55 clinical centers. Large DFUs were defined as above; median and small DFUs were below median area: 1.3 cm2 in Study 1 or 1.5 cm2 in Study 2. Large, small, and pooled DFUs that had completely healed or had not healed by week 12 of the study were tested for their association with percent area reduction at weeks 1–4. Diagnostic efficiency was calculated as the area under the Receiver Operating Characteristic curve (ROC), a plot of sensitivity (percent correctly diagnosed) as a function of 1-specificity (percent of false positives). Results: Most (75%) of the DFUs were 2 in area (range 0.50 cm2–24.65 cm2). After 12 weeks, 32% of control subjects from Study 1 (42 of 133 DFUs) healed, and 33% of Study 2 subjects healed (39 of 117 DFUs). Larger ulcers were less likely to heal in 12 weeks. For pooled DFUs, 50% area reduction at week 4 strongly predicted healing (P Authors’ Conclusions: Less than 50% area reduction after the first 4 weeks of care effectively predicted full-thickness DFU failure to heal by 12 weeks independent of ulcer area. Four weeks may be used as a clinical decision point to re-evaluate the treatment regimen for a DFU.
Clinical Perspective Identifying healing predictors alerts care providers to clinical pearls: aspects of care that promote or delay healing. Milic et al remind us that a VU patient who does not or cannot walk or flex his ankles or contract their calf muscles sufficiently to reduce edema is unlikely to heal, even with sustained, graduated multi-layer compression. VU healing is likely to be delayed for deep ulcers, a patient with an excessive BMI, or a patient who walks less than 200 meters (~2 blocks) daily, but these VU patients are likely to heal within a year. Milic et al did not explore early VU reduction in area as a predictor of healing, but we know from RCT post-hoc analyses that properly compressed VU reducing in area at least 30% during the first 2 weeks of care2 or 40% in the first 3 weeks3 are on the path to healing. Similar analyses show that the same is true for pressure ulcers that reduce in area at least 39% during the first 2 weeks of care,4 or DFUs that reduce at least 53% during the first 4 weeks of care,5 as confirmed by Snyder et al with a 4-week 50% reduction in DFU area. The Snyder et al conclusion is well worth heeding—if a DFU hasn’t reduced by half its area during the first 4 weeks of care, it is wise to re-evaluate the causes of tissue damage and the treatment regimen to avert catastrophe. Screening validity calculated from Snyder et al data are percent of patients correctly screened by the test, which is useful as an early clinical warning. •Positive predictive value: 54% of patients with > 50% closure at 4 weeks healed in 12 weeks •Negative predictive value: 96% of patients with 50% closure at 4 weeks •Specificity: 62% of patients unhealed in 12 weeks who had 6 reported between surgical debridement and faster DFU healing. Correlations observed are not necessarily causes. Correlations or associations may result from unidentified patient or ulcer factors that affect the likelihood of ulcer healing. It would take a RCT with debridement conditions randomly assigned to similar patient samples to prove definitively that surgical debridement delays VU healing or speeds DFU healing. This underscores the need for rigorous RCTs comparing the effects of surgical debridement to autolytic debridement with a hydrogel. Currently, autolytic debridement with a hydrogel is the only debridement standard of care that has RCT evidence of improved healing efficacy compared to gauze on a chronic wound.7
References 1. Kurd SK, Hoffstad OJ, Bilker WB, Margolis DJ. Evaluation of the use of prognostic information for the care of individuals with venous leg ulcers or diabetic neuropathic foot ulcers. Wound Repair Regen. 2009;17(3):318–325. 2. van Rijswijk L. Full-thickness leg ulcers: patient demographics and predictors of healing. Multi-Center Leg Ulcer Study Group. J Fam Pract. 1993;36(6):625-632. 3. Phillips TJ, Machado F, Trout R, Porter J, Olin J, Falanga V. The Venous Ulcer Study Group. Prognostic indicators of venous ulcers. J Am Acad Dermatol. 2000;43(4):627–630. 4. van Rijswijk L, Polansky M. Predictors of time to healing deep pressure ulcers. WOUNDS. 1994;6(5):159–165. 5. Sheehan P, Jones P, Caselli A, Giurini JM, Veves A. Percent change in wound area of diabetic foot ulcers over a 4-week period is a robust predictor of complete healing in a 12-week prospective trial. Diabetes Care. 2003;26(6):1879–1882. 6. Steed DL, Donohoe D, Webster MW, Lindsley L. Effect of extensive debridement and treatment on the healing of diabetic foot ulcers. Diabetic Ulcer Study Group. J Am Coll Surg. 1996;183(1):61–64. 7. Edwards J, Stapley S. Debridement of diabetic foot ulcers. Cochrane Database Syst Rev. 2010;20(1):CD003556.
Recognizing Venous Ulcers at Healing Risk Reference: Milic DJ, Zivic SS, Bogdanovic DC, Karanovic ND, Golubovic ZV. Risk factors related to the failure of venous leg ulcers to heal with compression treatment. J Vasc Surg. 2009;49(5):1242–1247. Rationale: Venous ulcer (VU) healing rates range from 40%–95% with compression. Factors predicting compromised VU healing include longer ulcer duration; larger surface area; more than 50% of the ulcer surface covered with fibrin, and an Ankle/Brachial Systolic Blood Pressure Index (ABI) of Objective: An open, prospective, single-center study determined risk factors associated with healing delay and nonhealing of VUs treated with a multilayer high compression bandaging system for 52 weeks. Methods: For 189 subjects with a VU at least 5 cm2 in area and 3 months in duration, factors were explored as predictors of either delayed or nonhealing during 52 weeks of treatment with multilayer high compression bandaging. Venous ulcer factors that were studied included surface area, coverage with > 50% fibrin slough, depth > 2 cm, history of surgical wound debridement, and time since ulcer onset. Patient factors that were tested included gender, age, history of deep vein thrombosis or surgery, body mass index (BMI), calf circumference reduction during the first 50 days of treatment, daily walking distance, calf/ankle circumference ratio Results: During 52 weeks of appropriate compression, 87.3% of the chronic VUs healed. Healing was predicted by ulcer duration 2, and during the first 50 days of treatment, new epithelium on > 10% of ulcer surface and/or a decrease in calf circumference > 3 cm. Predictors of delayed VU healing were initial ulcer depth > 2 cm, patient BMI > 33 kg/m2, walking P Authors’ Conclusions: Failure of VUs to heal during 1 year of treatment with multilayer high compression is associated with failure to resolve lower limb edema related to impaired calf muscle pump function.
Predicting Diabetic Foot Ulcer Healing Reference: Snyder RJ, Cardinal M, Dauphinee DM, Stavosky J. A post-hoc analysis of reduction in diabetic foot ulcer size at 4 weeks as a predictor of healing by 12 weeks. Ostomy Wound Manage. 2010;56(3):44–50. Rationale: Four-week percent area reduction has been suggested to distinguish diabetic foot ulcers (DFUs) that will heal in 12 weeks from those that will not heal. Objective: Determine whether a 50% area reduction during weeks 1–4 of standard wound care was associated with closure of large or small DFUs after 12 weeks of treatment. Methods: A post-hoc analysis identified healing predictors in 250 subjects with Type 1 or 2 diabetes and a full-thickness plantar or heel DFU. All subjects completed 12 weeks of standard control treatment with gauze and offloading in two randomized controlled trials of a dermal substitute conducted in 55 clinical centers. Large DFUs were defined as above; median and small DFUs were below median area: 1.3 cm2 in Study 1 or 1.5 cm2 in Study 2. Large, small, and pooled DFUs that had completely healed or had not healed by week 12 of the study were tested for their association with percent area reduction at weeks 1–4. Diagnostic efficiency was calculated as the area under the Receiver Operating Characteristic curve (ROC), a plot of sensitivity (percent correctly diagnosed) as a function of 1-specificity (percent of false positives). Results: Most (75%) of the DFUs were 2 in area (range 0.50 cm2–24.65 cm2). After 12 weeks, 32% of control subjects from Study 1 (42 of 133 DFUs) healed, and 33% of Study 2 subjects healed (39 of 117 DFUs). Larger ulcers were less likely to heal in 12 weeks. For pooled DFUs, 50% area reduction at week 4 strongly predicted healing (P Authors’ Conclusions: Less than 50% area reduction after the first 4 weeks of care effectively predicted full-thickness DFU failure to heal by 12 weeks independent of ulcer area. Four weeks may be used as a clinical decision point to re-evaluate the treatment regimen for a DFU.
Clinical Perspective Identifying healing predictors alerts care providers to clinical pearls: aspects of care that promote or delay healing. Milic et al remind us that a VU patient who does not or cannot walk or flex his ankles or contract their calf muscles sufficiently to reduce edema is unlikely to heal, even with sustained, graduated multi-layer compression. VU healing is likely to be delayed for deep ulcers, a patient with an excessive BMI, or a patient who walks less than 200 meters (~2 blocks) daily, but these VU patients are likely to heal within a year. Milic et al did not explore early VU reduction in area as a predictor of healing, but we know from RCT post-hoc analyses that properly compressed VU reducing in area at least 30% during the first 2 weeks of care2 or 40% in the first 3 weeks3 are on the path to healing. Similar analyses show that the same is true for pressure ulcers that reduce in area at least 39% during the first 2 weeks of care,4 or DFUs that reduce at least 53% during the first 4 weeks of care,5 as confirmed by Snyder et al with a 4-week 50% reduction in DFU area. The Snyder et al conclusion is well worth heeding—if a DFU hasn’t reduced by half its area during the first 4 weeks of care, it is wise to re-evaluate the causes of tissue damage and the treatment regimen to avert catastrophe. Screening validity calculated from Snyder et al data are percent of patients correctly screened by the test, which is useful as an early clinical warning. •Positive predictive value: 54% of patients with > 50% closure at 4 weeks healed in 12 weeks •Negative predictive value: 96% of patients with 50% closure at 4 weeks •Specificity: 62% of patients unhealed in 12 weeks who had 6 reported between surgical debridement and faster DFU healing. Correlations observed are not necessarily causes. Correlations or associations may result from unidentified patient or ulcer factors that affect the likelihood of ulcer healing. It would take a RCT with debridement conditions randomly assigned to similar patient samples to prove definitively that surgical debridement delays VU healing or speeds DFU healing. This underscores the need for rigorous RCTs comparing the effects of surgical debridement to autolytic debridement with a hydrogel. Currently, autolytic debridement with a hydrogel is the only debridement standard of care that has RCT evidence of improved healing efficacy compared to gauze on a chronic wound.7
References 1. Kurd SK, Hoffstad OJ, Bilker WB, Margolis DJ. Evaluation of the use of prognostic information for the care of individuals with venous leg ulcers or diabetic neuropathic foot ulcers. Wound Repair Regen. 2009;17(3):318–325. 2. van Rijswijk L. Full-thickness leg ulcers: patient demographics and predictors of healing. Multi-Center Leg Ulcer Study Group. J Fam Pract. 1993;36(6):625-632. 3. Phillips TJ, Machado F, Trout R, Porter J, Olin J, Falanga V. The Venous Ulcer Study Group. Prognostic indicators of venous ulcers. J Am Acad Dermatol. 2000;43(4):627–630. 4. van Rijswijk L, Polansky M. Predictors of time to healing deep pressure ulcers. WOUNDS. 1994;6(5):159–165. 5. Sheehan P, Jones P, Caselli A, Giurini JM, Veves A. Percent change in wound area of diabetic foot ulcers over a 4-week period is a robust predictor of complete healing in a 12-week prospective trial. Diabetes Care. 2003;26(6):1879–1882. 6. Steed DL, Donohoe D, Webster MW, Lindsley L. Effect of extensive debridement and treatment on the healing of diabetic foot ulcers. Diabetic Ulcer Study Group. J Am Coll Surg. 1996;183(1):61–64. 7. Edwards J, Stapley S. Debridement of diabetic foot ulcers. Cochrane Database Syst Rev. 2010;20(1):CD003556.
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