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

Abstract

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. Because 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. After institutional review board approval, all patients with ankle-brachial index/TBI performed at a single Veterans Affairs medical center from October 1, 2015, to September 31, 2022, were screened for foot wounds, TBI performed within 3 months of initial wound visit, and ipsilateral foot radiograph. Patient demographics, comorbidities, and outcomes including wound healing, mortality, and major amputation were recorded to December 31, 2023. Calcification was assessed via pMAC scoring, as well as present vs absent at the hallux (digital artery calcification [DAC]). Wounds in patients with and without DAC were then compared, with subanalysis by TBI and toe pressure ranges. Multivariable binary logistic regression was performed in IBM SPSS using the covariates of DAC, age, TBI, smoking, coronary artery disease, end-stage renal disease, congestive heart failure, and interval revascularization. Over the study period, 559 veterans with ankle-brachial index/TBI studies had foot wounds, of whom 248 also had a foot radiograph. These patients had 253 total wounds for analysis. Seventy-five wounds (30%) were in patients with DAC, which was associated with the presence of comorbidities including older age (72.6 ± 9.3 years vs 69.6 ± 10.9 years; P = .04), end-stage renal disease (10% vs 2%; P = .02), coronary artery disease (53% vs 32%; P < .01), congestive heart failure (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 cm vs 1.7 ± 1.5 cm; P = .08), diabetes (64% vs 57%; P = .33), hypertension (79% vs 80%; P = .74), mean Wound, Ischemia, and Foot Infection 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 weeks 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 a significant difference in any specific TBI range. After multivariate adjustment, DAC was not associated with impaired wound healing (odds ratio [OR], 1.1; 95% confidence interval [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 1-year mortality (OR, 2.3; 95% CI, 1.1-5.0). Digital calcification did not predict the inability to heal a foot-level wound; however, it was associated independently with doubled odds for 1 -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.