Digital calcification is associated with increased mortality and interval revascularization in Veterans with foot wounds.

Abstract

Objective: In patients with foot wounds related to chronic limb-threatening ischemia, pedal medial arterial calcification (pMAC) scoring has been proposed to predict risk of amputation and mortality. As pMAC scoring is complex, requiring assessment of five imaging regions, we investigated whether a simpler assessment of digital calcification at the hallux where toe brachial indices (TBI) are typically measured would predict outcomes in patients with foot wounds.

Methods: Following IRB approval, all patients with ABI/TBI performed at a single VA medical center from 10/1/2015-9/31/22 were screened for foot wounds, TBI performed within 3 months of initial wound visit, and ipsilateral foot X ray. Patient demographics, comorbidities, and outcomes including wound healing, mortality, and major amputation were recorded to 12/31/23. Calcification was assessed via pMAC scoring, as well as present versus absent at the hallux (digital artery calcification, DAC). Wounds in patients with and without DAC were then compared, with sub-analysis by TBI and toe pressure ranges. Multivariable binary logistic regression was performed in IBM SPSS utilizing the covariates of DAC, age, TBI, smoking, CAD, ESRD, CHF, and interval revascularization.

Results: Over the study period, 559 Veterans with ABI/TBI studies had foot wounds, of whom 248 also had a foot X-ray. These patients had 253 total wounds for analysis. 75 (30%) of wounds were in patients with DAC, which was associated with the presence of comorbidities including older age (72.6±9.3 vs 69.6±10.9 years, P=.04), ESRD (10% vs 2%, P=.02), CAD (53% vs 32%, P<.01), CHF (35% vs 19%, P=.02), and higher pMAC score (2.8±1.3 vs 0.5±0.9, P<.01), and inversely associated with smoking (11% vs 29%, P<.01). Wounds in patients with DAC had similar presenting wound length (2.1±2.0 vs 1.7±1.5 cm, P=.08), diabetes (64% vs 57%, P=.33), hypertension (79% vs 80%, P=.74), mean WIfI score (2.6±1.1 vs 2.5±1.2, P=.54), and history of prior revascularization (25% vs 18%, P=.23) as wounds in patients without DAC. Time to wound healing without major amputation (32±30 vs 28±28 weeks, P=.38), proportion of healing (72% vs 77%, P=.26), and major amputation (9% vs 4%, P=.15) were similar between groups. Patients with DAC were more likely to be treated with interval revascularization during the wound course (39% vs 23%, P=.01). One-year mortality was higher for patients with DAC generally (28% vs 11%, P<.01) without significant difference in any specific TBI range. Following multivariate adjustment, DAC was not associated with impaired wound healing (OR:1.1, 95% CI:0.6-2.1) or increased major amputation (OR:1.1, 95% CI:0.3-3.6), however DAC remained associated with increased odds for one year mortality (OR:2.3, 95% CI:1.1-5.0).

Conclusions: Digital calcification did not predict the inability to heal a foot-level wound however it was independently associated with doubled odds for one-year mortality as well as with higher rates of interval revascularization. DAC presence should be considered at wound presentation as a marker for higher risk patients who would benefit from intensive medical management and close follow up and may need revascularization to heal despite otherwise reassuring toe pressures.