Association of Vitamin D Deficiency with Frailty Phenotype and History of Falls among Older Lebanese Adults: Analysis of the LSAHA Study

Abstract

Background: Vitamin D deficiency, frailty, and falls are important concerns in later life and particularly in Lebanon, a lower-middle-income Eastern Mediterranean setting undergoing rapid population aging and economic strain, where evidence on geriatric vulnerability remains limited. Although vitamin D has plausible links to muscle strength, physical performance, and fall risk, findings remain mixed, and population-based evidence from Lebanon is lacking.

Objectives: This study examined the association of vitamin D deficiency with frailty phenotype and history of falls among older Lebanese adults. It also explored whether frailty mediated the association between vitamin D deficiency and falls.

Methods: We conducted a cross-sectional secondary analysis of baseline data drawn from the population-based Lebanon Study on Aging and HeAlth (LSAHA) and included 2,326 community-dwelling adults aged 60 years and older in Beirut and Zahle with non-missing data on vitamin D status, frailty phenotype, and falls history. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D [25(OH)D] below 20 ng/ml. A sensitivity analysis redefined vitamin D deficiency using a stricter cutoff of <15 ng/ml and repeated the falls and frailty regression models. Frailty, the primary outcome, was assessed using a modified three-component phenotype based on weakness, slowness, and low physical activity, and was categorized as robust = 0 components, pre-frail = 1, and frail = ≥2. Falls, the secondary outcome, were defined as self-reported history of one or more falls in the previous two years; recurrent falls were not modeled separately in the main analysis. Survey-weighted descriptive, bivariate, logistic, and multinomial logistic regression analyses were conducted in Stata 18, followed by exploratory mediation analysis.

Results: Participants had a survey-weighted mean age of 71.4 years, and 53.8% were women. Vitamin D deficiency was present in 43.3% of participants, 45.6% reported falls, and frailty status was distributed as 67% robust, 27.2% pre-frail, and 5.8% frail. In adjusted analyses, vitamin D deficiency was not independently associated with falls (adjusted OR 1.07, 95% CI 0.79 to 1.45), pre-frailty (adjusted RRR 0.92, 95% CI 0.65 to 1.30), or frailty (adjusted RRR 1.30, 95% CI 0.72 to 2.35). In sensitivity analyses using the <15 ng/ml cutoff, severe vitamin D deficiency was not significantly associated with falls (OR 1.31, 95% CI 0.88 to 1.93), pre-frailty (RRR 0.90, 95% CI 0.62 to 1.32), or frailty (RRR 1.85, 95% CI 0.93 to 3.68), although the frailty estimate was stronger in magnitude. Older age, multimorbidity, and residence in Zahle were associated with pre-frailty and frailty. Frailty did not mediate the association between vitamin D deficiency and falls.

Discussion: Vitamin D deficiency was not an independent determinant of frailty or falls in the primary analysis, and severe deficiency using a <15 ng/ml cutoff showed stronger but still statistically non-significant associations. Instead, geriatric vulnerability appeared to be more strongly shaped by age, multimorbidity, and contextual factors. Longitudinal analyses are needed to clarify temporality and assess whether vitamin D status predicts future frailty transitions and incident falls.