DEVELOPING A CLINICAL DIAGNOSTIC TOOL FOR THE IDENTIFICATION OF OLDER ADULTS WITH HYPOVITAMINOSIS D

Abstract

Introduction: Hypovitaminosis D is highly prevalent among older adults and associated with adverse health events. To rationalize vitamin D assays and save health costs, our objectives were to develop and test a clinical diagnostic tool for the identification of older community-dwellers with hypovitaminosis D. Methods: 1924 community-dwelling volunteers ≥65 years without vitamin D supplements were recruited in this cross-sectional study. A set of clinical variables (age, gender, living alone, individual deprivation, body mass index, undernutrition, polymorbidity, number of drugs used daily, psychoactive drugs, biphosphonates, strontium, calcium supplements, falls, fear of falling, vertebral fractures, Timed Up & Go test, walking aids, lower-limb proprioception, handgrip strength, visual acuity, wearing glasses, cognitive disorders, sad mood) was recorded from standardized questionnaires and medical examination at the time of serum 25-hydroxyvitamin D (25OHD) measurement. Hypovitaminosis D was defined as serum 25OHD ≤75 nmol/L, ≤50 nmol/L or ≤25 nmol/L. The whole sample was separated into training and testing subsets to design, validate and test an artificial neural network (multilayer perceptron, MLP). Results: 1729 participants (89.9%) had 25OHD ≤75 nmol/L, 1288 (66.9%) had 25OHD ≤50 nmol/L, and 525 (27.2%) had 25OHD ≤25 nmol/L. MLP using 16 clinical variables was able to diagnose hypovitaminosis D ≤75 nmol/L with accuracy = 96.3%, Area under curv (AUC) = 0.938, and κ=79.3 indicating almost perfect agreement. It was also able to diagnose hypovitaminosis D ≤50 nmol/L with accuracy = 81.5, AUC=0.867 and κ=57.8 (moderate agreement); and hypovitaminosis D ≤25 nmol/L with accuracy = 82.5, AUC=0.835 and κ=55.0 (moderate agreement). Conclusions: We developed an algorithm able to identify, from 16 clinical variables, older community-dwellers with hypovitaminosis D. Such inexpensive tool should help clinicians in decisions to supplement their patients without resorting to blood tests.