Abstract
Objectives: To evaluate the frequency of hypovitaminosis D among older adults and its
association with the level of functionality.
Methods: This cross-sectional observational study of older adults residing in a
non-profit long-term care facility assessed functionality with the Katz
Index of Independence in Activities of Daily Living. Vitamin D levels were
classified as: deficient (< 20 ng/mL), insufficient (21–29 ng/mL), or
normal (≥ 30 ng/mL). We used the chi-square test and Student’s
t-test to compare dichotomous and continuous variables,
respectively. Analysis of variance with Tukey’s post hoc test was used to
assess differences between groups.
Results: The sample consisted of 63 individuals whose mean age was 81 (61–113) years:
36 (55.4%) women and 27 (44.6%) men. The mean vitamin D level was 18.6
ng/mL, being < 30 ng/mL in 84.1%. The level was normal in 10 (15.9%),
insufficient in 17 (27%), and deficient in 36 (57.1%). Vitamin D deficiency
was present in 76.5% of those with total functional dependence (Katz =
5–6).
Conclusions: We observed a high frequency of hypovitaminosis D, especially vitamin D
deficiency, which was very common among those with significant functional
dependence.
Keywords: Older adult, long-term care facility, vitamin D, functional status.
Resumo
Objetivos: Avaliar a frequência de hipovitaminose D em idosos de uma instituição
filantrópica de longa permanência e sua associação com grau de
funcionalidade.
Metodologia: Estudo transversal, observacional e analítico de idosos de uma instituição
filantrópica de longa permanência. A funcionalidade foi avaliada pela Escala
de Katz. Os níveis de vitamina D foram classificados em: deficiência
(valores menores que 20 ng/mL); insuficiência (valores entre 21 – 29 ng/mL)
e normais (valores igual ou superior a 30 ng/mL). Empregamos teste
qui-quadrado e t de student, para compararmos variáveis
dicotômicas e contínuas, respectivamente; e análise de variância (ANOVA) com
teste post hoc de Tukey, para avaliarmos as diferenças
entre os grupos.
Resultados: Sessenta e três indivíduos foram analisados com média de idade de 81 anos (61
– 113), sendo 36 (55,4%) mulheres e 27 (44,6%) homens. A média de vitamina D
foi 18,6 ng/mL, 84,1% com níveis menores que 30 ng/mL; dez apresentaram
níveis normais (15,9%), 17 com insuficiência (27%) e 36 com deficiência
(57,1%); ainda, 76,5% dos portadores de dependência funcional total (Katz =
5 – 6) apresentam deficiência de vitamina D.
Conclusões: Observamos uma alta frequência de hipovitaminose D, especialmente
deficiência, muito frequentes naqueles com dependência funcional
importante.
Palavras-Chaves: Pessoa idosa, instituição de longa permanência para idosos, vitamina D, estado funcional.
Carátula del artículo
Functionality and 25-hydroxyvitamin D levels in institutionalized
older adults
Funcionalidade e níveis de 25-hidroxivitamina D em idosos
institucionalizados
Sarah de Jesus Francisco
Escola Superior de Ciências da Santa Casa de
Misericórdia de Vitória, Brazil
Manoela Morgado Horta Barros
Escola Superior de Ciências da Santa Casa de
Misericórdia de Vitória, Brazil
Ingrid Ardisson Colodete
Escola Superior de Ciências da Santa Casa de
Misericórdia de Vitória, Brazil
Caroline Delboni Nascimento
Escola Superior de Ciências da Santa Casa de
Misericórdia de Vitória, Brazil
Waleska Binda Wruck
Escola Superior de Ciências da Santa Casa de
Misericórdia de Vitória, Brazil
Renato Lirio Morelato renato.morelato@emescam.br
Escola Superior de Ciências da Santa Casa de
Misericórdia de Vitória, Brazil
Geriatrics, Gerontology and Aging, vol. 17, e2300022, 2023
Sociedade Brasileira de Geriatria e Gerontologia,
SBGG
Received: 03 April 2023
Accepted: 30 August 2023
INTRODUCTION
Vitamin D is a hormone produced mainly in the skin. In response to ultraviolet light,
keratinocytes in the epidermis convert 7-dehydrocholesterol (an immediate precursor
to cholesterol) into vitamin D3. Production of vitamin D3 in the skin is affected by
a variety of factors; aging also reduces the skin’s ability to synthesize vitamin
D.1
Vitamin D3 produced in the skin is biologically inert and must be hydroxylated in
successive steps to become active. The main function of 25-hydroxyvitamin D, the
active form of vitamin D, is to maintain the concentration of circulating calcium by
stimulating absorption in enterocytes and increasing bone resorption.1
Vitamin D deficiency, classically defined as values < 20 ng/mL, is very common in
older adults, especially those who have been institutionalized. This arises from low
sun exposure, low concentrations of 7-dehydrocholesterol in the skin2 and insufficient dietary intake of vitamin
D.3
Studies on the association between vitamin D levels and functionality are limited by
the fact that vitamin D deficiency is common among older adults (the prevalence is
approximately 90%).4,5 The Longitudinal Aging Study Amsterdam, which included 1237
older adults (65–88 years), found an association between vitamin D deprivation and
functional limitation.6
Thus, the objective of this study was to determine the frequency of hypovitaminosis D
and its association with functionality among residents of a non-profit long-term
care facility.
METHODS
This was a cross-sectional observational study of older adults from a long-term care
facility in Cariacica, Espírito Santo, Brazil. The dichotomous variables were:
arterial hypertension (blood pressure ≥ 150/90 mmHg or regular use of
antihypertensives), diabetes mellitus (fasting blood glucose > 126 mg/dL or use
of oral hypoglycemic agents or insulin), and dementia (diagnosed according to DSM-IV
or National Institute of Neurological and Communicative Diseases and
Stroke/Alzheimer’s Disease and Related Disorders Association criteria).7 No participant had impaired kidney function.
Functionality was assessed using the Katz Index of Independence in Activities of
Daily Living, which assesses self-care in 6 domains: independent dressing, moving in
and out of bed, using the toilet, washing, eating, and controlling urine and fecal
continence. Each domain was assigned 1 or 0 points if the participant was dependent
or independent, respectively. Thus, total scores ranged from 0 to 6 points8 and were classified as complete independence
(Katz = 0), mild dependence (Katz = 1–2), moderate dependence (Katz = 3–4) or total
dependence (Katz = 5–6).
Serum levels of 25-hydroxyvitamin D were collected, in addition to total cholesterol,
glucose, glycated hemoglobin, creatinine, sodium, hemoglobin and hepatic
transaminases (see Table 1). These
examinations were performed between July and August. Levels of 25-hydroxyvitamin D
were classified as: deficient (< 20 ng/mL), insufficient (21–29 ng/mL) or normal
(≥ 30 ng/mL: competition-type electrochemilu-minescent immunoassay).9 Residents who were taking vitamin D2/D3
supplements or multivitamins were excluded. All individuals (or their legal
guardians) who agreed to participate in the study and provided written informed
consent were included.
TABLE 1
Demographic and laboratory profile of the participants.
* t-test for independent samples (p ≤ 0.05). GOT: serum
glutamic-oxaloacetic transaminase; GTP: serum glutamic-pyruvic
transaminase.
Categorical variables were represented as percentages, and continuous variables were
represented as mean (SD). The association between the dependent variable (vitamin D)
and the independent variables was analyzed using the chi-square test. Student’s
t-test for independent samples was used to compare continuous
variables. One-way analysis of variance with Tukey’s post hoc test was used to
compare variables between groups with normal, insufficient, and deficient vitamin D
levels.
The data were analyzed in IBM SPSS Statistics 25.0 (IBM, Armonk, NY, USA). We
considered p-values < 0.05 significant. This research project was approved by the
Escola Superior de Ciências da Santa Casa de Misericórdia de Vitória research ethics
committee (number 29112914.9.0000.5065).
RESULTS
We analyzed 63 older adults: 36 women (55.4%) and 27 men (44.6%) with a mean age of
81 (61–113) years, distributed in the following age groups: 61–74 years (n = 15;
23.8%), 75–84 years (n = 23; 36.5%), and > 85 years (n = 25; 39.7%). The mean
vitamin D level was 18.695 ng/mL, being insufficient in 17 (27%) residents,
deficient in 36 (57.1%), and normal in 10 (15.9%). Individuals with normal vitamin D
levels were younger, with a mean age of 77 (SD, 6) years. The mean age in the
insufficient and deficient groups was 80 (SD, 7) and 82 (SD, 1) years, respectively
(p = 0.26). We found no association between vitamin D level and dementia (p = 0.48),
high blood pressure (p = 0.59), or diabetes mellitus (p = 0.50).
The participants had been institutionalized for 1-8 (mean 4.46) years. The mean
residence time was 2 (1–5) years in the normal vitamin D group, 6.53 (1–18) years in
the insufficient group, and 4.23 (1–17) years in the deficient group (p = 0.02). A
post hoc analysis of variance test revealed a significant
difference (p = 0.02) in residence time between the normal and insufficient
groups.
A total of 24 participants (40%) were completely independent in activities of daily
living (Katz = 0), 16 (24.6%) were mildly dependent (Katz = 1–2), 6 (9.3%) were
moderately dependent (Katz = 3–4), and 17 (26.1%) were totally dependent (Katz =
5–6). The distribution of groups according to functional dependence and
hypovitaminosis D is shown in Table 2.
TABLE 2
The relationship between functionality and vitamin D levels.
χ2 test (p = 0.31). ADL: Activities of daily living (Katz
Index).
When correlating functional dependence with 25-hydroxyvitamin D levels in analysis of
variance with Tukey’s post hoc test, the mean vitamin D level was 19.78 ng/mL in
independent individuals, 22.10 ng/mL in mildly dependent individuals, 19.49 ng/mL in
moderately dependent individuals, and 13.51 ng/mL in totally dependent individuals
(p = 0.02). There was a significant difference (p = 0.02) between the totally and
mildly dependent groups in the post hoc analysis. A high (23.8%; 15 individuals) but
non-significant (p = 0.23) percentage of participants had severe vitamin D
deficiency (< 10 ng/mL).
DISCUSSION
The frequency of older adults with abnormal vitamin D levels was 84.1% (mean level 18
ng/mL), with 57.1% classified as deficient (< 20 ng/mL). Similar results have
been observed in other studies, ie, a significant portion of institutionalized older
adults have deficient vitamin D levels.10,11
A total of 23.8% of the institution’s residents had severe vitamin D deficiency (<
10 ng/mL), which corresponded to 46.7% of those with high functional dependence.
Functional dependence was thus an important determinant of vitamin D deficiency.
This finding is corroborated by other studies, such as Alekena et al.,12 who found an association between vitamin D
deficiency and dependence in activities of daily living.
In a 2007 study of 117 institutionalized older Brazilians, Saraiva et al.13 observed that vitamin D levels were
deficient in 40.7% and insufficient in 30.5%. Among outpatients, vitamin D levels
were deficient in 15.8% and insufficient in 40.0%. Institutionalization had the
greatest influence on the results of the multivariable analysis. Therefore, it
appears that individuals with more pronounced functional dependence have a higher
frequency of vitamin D deficiency due to reduced sun exposure.14
Studies have demonstrated an association between vitamin D deficiency and decreased
insulin secretion, insulin resistance, type 2 diabetes mellitus, and metabolic
syndrome. However, the mechanisms that justify such findings are still poorly
understood.15,16 Recent evidence has shown that vitamin D is a neurosteroid
that is important in aging and age-associated cognitive decline. Thus,
hypovitaminosis D has been associated with a risk of dementia and Alzheimer’s
disease.17 However, in the present study
we found no association between vitamin D levels and dementia, high blood pressure,
or diabetes mellitus.
Those with normal vitamin D levels were younger and had been institutionalized for
less time, but these differences were not significant. Due to low sun exposure,
poorer nutritional status, and a high prevalence of frailty, long-term care facility
residents are at high risk for vitamin D deficiency, as shown by Gau et al.18
Our study was limited by its sample size and by sampling a single long-term care
facility. The fact that the facility was for at-risk individuals could have affected
the low dietary intake of vitamin D. The scarcity of recent literature on this theme
limited comparison with other studies. Due to the study design, causal links between
the variables could not be determined.
The high frequency of vitamin D deficiency in the present study leads us to recommend
monthly supplementation with 50,000 IU vitamin D, which is a safe and effective dose
for older adults.19
CONCLUSION
We observed a high frequency of hypovitaminosis D, especially vitamin D deficiency,
among institutionalized older adults who are functionally dependent in activities of
daily living.
Acknowledgements
The authors would like to thank Laboratório Pretti and Dr. Renato Pretti for
providing examinations at no cost.
