Lower serum zinc levels are associated with delayed wound healing in people with diabetic foot ulcers
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Authors: Valayatham,V. M.;McGill,M.;Bolton,T.;Nube,V.;Twigg,S.
Publication: Diabetes research and clinical practice
Start Page: S236
Background: NSW 2006, Australia. Whilst zinc is thought to be important in optimising wound healing, and blood zinc levels are on average lower in people with diabetes, no studies have systematically reported relationships between blood zinc and healing outcomes in people with diabetic foot ulcers. The aim in this study was to compare initial blood zinc levels with subsequent ulcer healing outcomes in a series of people with diabetes receiving multidisciplinary foot ulcer care.
Method: Patients with foot ulcers receiving treatment in a High Risk Foot Service, were audited across 1.1.07 to 31.4.14. Serum zinc (n = 188) was determined at baseline testing, and ulcer healing was objectively assessed, with acetate tracings undertaken real time and then ulcer area was calculated using BERSOFT® software. Ulcer healing rate at week 12 and time to conservative (non-surgical) final healing were each determined. Data was analysed with SPSS22 by univariate, then multivariate analysis
Result: Of the series, 79.8% were male, with age 62.0Â±11.5 years (mean Â± SD), and diabetes duration 16.0Â±9.4 years. Chronic kidney disease was present in 28.7% and congestive cardiac failure in 25.5%. Initial ulcer area was 286Â±657mm2. Most ulcers were Texas Grade 1 (82.4%) and Stage B (50.0%); 64.9% were neuropathic, 27.1% neuroischaemic, 1.1% ischaemic and 6.9% were traumatic or pressure based. Mean serum zinc across the cohort was 13.2Â±2.6 mmol/L, and thus 1.8 mmol/L below the average of the reference mean (10-20 mmol/L). Complete healing at week 12 was 37.4%, with a mean rate of 24.8Â±44.8mm2/week. Ulcers which healed conservatively at study end comprised 72.3% of the cohort with final healing rate of 18.1Â±29.6mm2/week. In contrast, 17% required admission for surgical debridement with 12.7% resulting in amputation. By ANOVA, there was a significant association of zinc levels with healing rates atweek 12 and final healing rates, favouring median level zincs for healing rather than lower serum zinc. In the first tertile of serum zinc (Zn < 13) compared with the second zinc tertile (Zn 13-14 mmol/L), mean healing rate at week 12 was 18.9 vs 38.0mm2/week p = 0.04, (6.9% vs 9.3 % of initial ulcer area per week), and final healing rate was 14.5 vs 26.8mm2/week, p = 0.05 (5.3 vs 6.6 % of initial ulcer area per week). By ANCOVA, after controlling for age, serum albumin, serum creatinine, known ischaemic heart disease and initial ulcer area, baseline zinc tertiles did not significantly associate with final healing rates, suggesting that zinc levels may cosegregate with co-morbidity. The % of ulcers that finally healed conservatively did not differ across tertiles of serum zinc
Conclusion: In conclusion, this data indicates that foot ulcers in people who have lower serum zinc levels are slower to heal. While it is unclear whether lower serum zinc may be a marker or amediator of disease, the known bioactivity of zinc in wound healing suggests that a randomised controlled trial of systemic zinc therapy should be considered in people with diabetic foot ulceration who are receiving ulcer treatment in multidisciplinary high risk foot services.