Association of Serum 25-Hydroxyvitamin D Deficiency with Risk of Incidence of Disability in Basic Activities of Daily Living in Adults >50 Years of Age

Abstract

Background Vitamin D deficiency compromises muscle function and is related to the etiology of several clinical conditions that can contribute to the development of disability. However, there are few epidemiological studies investigating the association between vitamin D deficiency and the incidence of disability. Objectives We aimed to assess whether vitamin D deficiency is associated with the incidence of disability in basic activities of daily living (BADL) and to verify whether there are sex differences in this association. Methods A 4-y follow-up study was conducted involving individuals aged 50 y or older who participated in ELSA (English Longitudinal Study of Ageing). The sample consisted of 4814 participants free of disability at baseline according to the modified Katz Index. Vitamin D was assessed by serum 25-hydroxyvitamin D [25(OH)D] concentrations and the participants were classified as sufficient (>50 nmol/L), insufficient (>30 to ≤50 nmol/L), or deficient (≤30 nmol/L). Sociodemographic, behavioral, and clinical characteristics were also investigated. BADL were re-evaluated after 2 and 4 y of follow-up. The report of any difficulty to perform ≥1 BADL was considered as an incident case of disability. Poisson models stratified by sex and controlled for sociodemographic, behavioral, and clinical characteristics were carried out. Results After 4-y follow-up, deficient serum 25(OH)D was a risk factor for the incidence of BADL disability in both women (IRR: 1.53; 95% CI: 1.16, 2.03) and men (IRR: 1.44; 95% CI: 1.02, 2.02). However, insufficient serum 25(OH)D was not a risk factor for the incidence of BADL disability in either men or women. Conclusions Independently of sex, deficient serum 25(OH)D concentrations were associated with increased risk of incidence of BADL disability in adults >50 y old and should be an additional target of clinical strategies to prevent disability in these populations.

Sex differences in vitamin D metabolism, serum levels and action

“…Moreover, the risk of basic activities of daily living (BADL) disability is related to vitamin D deficiency in both sexes; however, in females, this risk is much higher (53% vs. 44%) (69). In addition, a greater risk of female skeletal abnormalities associated with vitamin D deficiency was confirmed by a study on so-called residual rickets.…”

“…Osteoporosis and osteopenia were found in as many as 91% of women with PD, while in the group of men with PD, the same diseases were present in 61% of respondents (66). Interesting information is provided by a case study that searched for differences in the type of hip fracture in relation to 25 Further, a UK cross-sectional study, using data from the English Longitudinal Study of Aging (ELSA) and conducted with people over 50 years old, demonstrated that a higher plasma concentration of 25(OH)D lowers the risk of disability in women, but not in men (69).…”

Sex Differences in Vitamin D Status as a Risk Factor for Incidence of Disability in Instrumental Activities of Daily Living: Evidence from the ELSA Cohort Study

“…Serum 25(OH)D concentrations were analyzed in the Royal Victoria Infirmary (Newcastle upon Tyne, United Kingdom) by DiaSorin Liaison immunoassay, which provides the total circulating 25(OH)D concentrations and has an analytical sensitivity of 7.5 nmol/L, with a variation coefficient ranging from 8.7% to 9.4%. All assays were performed in duplicate, and the laboratory that performed the 25(OH)D analyses participated in the Vitamin D External Quality Assessment Schemes (DEQAS) [ 25 ]. According to the Institute of Medicine, serum 25(OH)D concentrations were classified as: sufficient (>50 nmol/L), insufficient (>30 and ≤50 nmol/L) and deficient (≤30 nmol/L) [ 26 ].…”

“…The socioeconomic characteristics included age (grouped into five 10-year categories as 50–59; 60–69; 70–79; 80–89 and 90 or more), race (white and non-white), conjugal life (with or without), schooling (>13 years; 12–13 years; ≤11 years) and total household wealth classified in quintiles [ 25 ].…”

“…The health-related behaviors included were smoking status (non-smoker, former smoker, or current smoker); frequency of alcohol consumption (rarely or never if 1 day a week, frequently if 2–6 days a week or daily). Based on an instrument validated by the HAS to assess the level of physical activity [ 27 ], a participant was considered active (vigorous or moderate physical activity more than once a week), or sedentary (vigorous or moderate physical activity once per week, one to three times per month, hardly ever or never; any mild physical activity) [ 25 ].…”