Host Susceptibility Phenotypes and Construction of an Inflammation-Vascular-Metabolic (IVM) Integrated Score for Hard-to-Heal Wounds After Low-Energy Foot Trauma in Older Adults.

BACKGROUND

Older adults with low-energy trauma-initiated foot wounds often become hard-to-heal, but prognostic tools tailored to this scenario are scarce.

METHODS

In this single-center retrospective cohort, we included consecutive patients aged ≥65 years with below-malleoli low-energy trauma-initiated foot wounds. Baseline predictors were the first laboratory values within 48 h and an ordinal perfusion/ischemia category derived from available ABI, pedal Doppler waveform findings, and toe-based measures. Hard-to-heal was failure of complete epithelialization without drainage by 12 weeks (major amputation classified as not healed). Latent class analysis defined susceptibility phenotypes. An interpretable 6-variable inflammation-vascular-metabolic (IVM) model was developed using logistic regression with multiple imputation and bootstrap internal validation.

RESULTS

Among 697 patients (median age 74 years), 332 (47.6%) were hard-to-heal at 12 weeks. Phenotypes showed graded risk (lowest to highest): relatively resilient (n=143, hard-to-heal 26/143), renal-hypoalbuminemia (n=165, hard-to-heal 81/165), metabolic-inflammatory (n=206, hard-to-heal 110/206), and ischemia-dominant (n=183, hard-to-heal 115/183). Adjusted odds ratios versus resilient were 3.8 (95% CI 2.3-6.4), 4.5 (2.8-7.4), and 6.1 (3.7-10.1), respectively. The IVM model achieved optimism-corrected AUC 0.80 (95% CI 0.77-0.83) with calibration slope 0.94 (intercept -0.03), stratified observed event rates to 19.7% (50/254), 48.8% (137/281), and 89.5% (145/162), and showed net benefit across threshold probabilities ~0.25-0.70.

CONCLUSION

In this retrospective single-center cohort, distinct susceptibility phenotypes were identifiable and the IVM score provided internally validated early risk stratification. External validation and prospective evaluation are warranted before routine clinical implementation.