Development and validation of a physical frailty phenotype index-based model to estimate the frailty index.

BACKGROUND: The conventional count-based physical frailty phenotype (PFP) dichotomizes its criterion predictors-an approach that creates information loss and depends on the availability of population-derived cut-points. This study proposes an alternative approach to computing the PFP by developing and validating a model that uses PFP components to predict the frailty index (FI) in community-dwelling older adults, without the need for predictor dichotomization. METHODS: A sample of 998 community-dwelling older adults (mean [SD], 68 [7] years) participated in this prospective cohort study. Participants completed a multi-domain geriatric screen and a physical fitness assessment from which the count-based PFP and the 36-item FI were computed. One-year prospective falls and hospitalization rates were also measured. Bayesian beta regression analysis, allowing for nonlinear effects of the non-dichotomized PFP criterion predictors, was used to develop a model for FI ("model-based PFP"). Approximate leave-one-out (LOO) cross-validation was used to examine model overfitting. RESULTS: The model-based PFP showed good calibration with the FI, and it had better out-of-sample predictive performance than the count-based PFP (LOO-R2, 0.35 vs 0.22). In clinical terms, the improvement in prediction (i) translated to improved classification agreement with the FI (Cohen's kw, 0.47 vs 0.36) and (ii) resulted primarily in a 23% (95%CI, 18-28%) net increase in FI-defined "prefrail/frail" participants correctly classified. The model-based PFP showed stronger prognostic performance for predicting falls and hospitalization than did the count-based PFP. CONCLUSION: The developed model-based PFP predicted FI and clinical outcomes more strongly than did the count-based PFP in community-dwelling older adults. By not requiring predictor cut-points, the model-based PFP potentially facilitates usage and feasibility. Future validation studies should aim to obtain clear evidence on the benefits of this approach.

A Clinician-Free Method Using Top-View Photography for Screening and Monitoring Hallux Valgus.

BACKGROUND: Hallux valgus is a progressive foot deformity that commonly affects middle-aged women. The aim of this study was to develop a novel method using only top-view photographs to assess hallux valgus severity. METHODS: A top-view digital photograph was taken of each foot of 70 female participants. Two straight lines were drawn along the medial edge of the great toe and forefoot, and the included angle (termed bunion angle) was measured using a free software program. Each foot was also assessed by a clinician using the Manchester scale as no (grade 1), mild (grade 2), moderate (grade 3), or severe (grade 4) deformity. RESULTS: The mean bunion angles of the 140 feet were 6.7°, 13.5°, and 16.2° for Manchester grades 1, 2, and 3, respectively (no foot was in grade 4). The reliability was excellent for both intrarater (intraclass correlation coefficient [ICC] = 0.93-0.95) and interrater (ICC = 0.90) assessments. Receiver operating characteristic curves determined the optimal bunion angle cutoff value for screening hallux valgus to be 9°, which gives 89.2% sensitivity and 74.2% specificity. CONCLUSIONS: The bunion angle is a reliable, clinician-free method that can potentially be integrated into a smartphone app for easy and inexpensive self-assessment of hallux valgus.

Reliability of peak foot pressure in patients with previous diabetic foot ulceration.

BACKGROUND: Previous reliability studies on peak plantar pressure measurements in patients with previous diabetic foot ulceration (DFU) did not stratify their analyses according to whether the foot had a previous ulcer. RESEARCH QUESTION: Does test-retest reliability of peak foot pressure measurements from the various foot regions differ between the ulcerated and non-ulcerated feet? METHODS: Data from 23 participants with peripheral neuropathy and healed plantar DFU were analysed in this test-retest reliability comparison study. Plantar pressure was evaluated on two sessions using Pedar®-X in-shoe system, with a mean of 7.2 days (SD = 1.6) between sessions. RESULTS: The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for 10 foot regions. Overall, test-retest reliability was excellent (ICCs, 0.82 to 0.95) for all peak pressure variables. CV ranged between 6.3% and 18.3%, and exceeded 15% over the hallux and medial forefoot regions in the ulcer foot (18.3% and 16.4%, respectively). Hallux peak pressure CV was significantly higher over the ulcer foot than over the non-ulcer foot (5.7%, 95% CI, 1.7%-10.2%). Peak pressure CV over the forefoot also tended to be higher over the ulcer foot (medial forefoot: 6.1%, 95% CI, -0.5%-14.5%; lateral forefoot: 4.1%, 95%CI, -0.7%-11.1%). SIGNIFICANCE: Peak plantar foot pressure may be useful to distinguish between groups of patients with peripheral neuropathy and healed plantar DFU. However, clinical decisions based on ulcer foot hallux and forefoot peak pressure measurements should be interpreted with caution.