**3. Results**

The power of the study was 99.7% (with continuity correction), considering a 95% confidence interval. The calculation was obtained from 109 exposed participants and 44 unexposed participants, resulting in a prevalence of vitamin D insufficiency of 71% and 28%, respectively. Thus, the prevalence ratio (PR) was equal to 2.5, with a difference of 43% among the prevalences.

The mean age of the elderly individuals was 81.7 (9.2) years, ranging from 60–103. Thus, they were a long-living population, and there were more females (78.4%) than males. It was found that 64.5% of them had some level of education, 70.6% lived in nonprofit institutions, and that the average age-adjusted time of institutionalization was 29.4%. The BMI values indicated that 46.4% of the elderly individuals were thin.

It was found that 60.3% showed signs of loss of muscle mass, according to calf circumference. Most of the elderly individuals did not practice physical activity, had moderate-to-severe cognitive impairment, and showed multimorbidity (Table 1).


**Table 1.** General, anthropometric, lifestyle, and health characteristics of institutionalized elderly individuals (*n* = 153).


a n =


**Table 1.** *Cont.*

Concerning functional status, 31.8% of the elderly individuals were classified as "A" (independent for eating, continence, locomotion, toilet use, dressing, and bathing), followed by 16.2% in the item "G" (dependent on performing the above six functions). Dietary intake of vitamin D was 2.8 (3.2) μg/day, resulting in a high prevalence of inadequacy (95.4%), in addition to low frequency in the use of vitamin D supplementation (5.9%). The prevalence of hypovitaminosis D in the study population was 71.2%, with a mean value of 23.9 (16.6) ng/mL for 25(OH)D/mL. No participant was categorized in the winter season according to the criteria applied to the distribution of elderly individuals by seasons (Table 2).

139.



a median (inter-quartile range between 25 and 75, respectively); b according to the diagnosis of vitamin D status.

There was an association between 25(OH)D and summer (*p* = 0.046), and there were no associations with any other independent variables (all *p* > 0.05) (Table 3).


**Table 3.** Association between serum 25(OH)D concentration and variables of the theoretical model.


**Table 3.** *Cont.*

a Prevalence Ratio.
