Deficiência de 25(OH)D como fator de risco para incidência de incapacidade funcional em indivíduos maiores de 50 anos – conclusões do estudo ELSA

Abstract

Introduction: The 25(OH)D deficiency has stood out for its recognized negative repercussion on the musculoskeletal systems, such as the reduction of strength and muscle mass; in the central nervous system, such as the predisposition to cognitive decline, and in the other body systems, favoring several clinical conditions, which can have an impact on the decrease in functional capacity in older individuals. However, there is little and conflicting epidemiological evidence demonstrating the association of 25(OH)D deficiency with the incidence of disability. Objectives: The present study aims to verify if the deficiency of 25(OH)D is a risk factor for incidence of disability in basic activities (BADL) and instrumental activities of daily living (IADL) and if there is a sex difference on these associations. Method: This is a longitudinal study with four years of follow-up involving people aged ≥ 50 years participating in the English Longitudinal Study of Ageing (ELSA). In the study of incidence of disability in BADL, 4,814 participants without disability were included in the baseline according to the modified Katz index. In the study of incidence of disability in IADL, 4,768 participants without disability were included in the baseline according to the modified Lawton index. The 25(OH)D was measured and the participants were classified as having sufficiency (> 50 nmol/L), insufficiency (> 30 and ≤ 50 nmol/L) and deficiency (≤ 30 nmol/L). Sociodemographic, behavioral and clinical characteristics were also assessed at baseline and considered control variables in the Poisson models stratified by sex. With two and four years of follow-up, BADL and IADL were reevaluated. An incident of disability was considered to be a report of difficulty in one or more activities in the Katz and Lawton Indexes. Results: 25(OH)D deficiency was a risk factor for incidence of BADL disability in women (IRR = 1.54; 95% CI 1.17 – 2.03) and men (IRR = 1.43; 95% CI 1.02 – 2.00) and risk factor for incidence of disability in IADL only in men (IRR = 1.40; 95% CI 1.01 – 1.95). Conclusions: Despite the fact that 25(OH)D deficiency is a risk factor for incidence of disability in BADL in both sexes, only men were at such risk for the incidence of disability in IADL. Since 25(OH)D deficiency is a modifiable condition, it must be the target of therapeutic strategies avoiding installation or progression of functional disability