TO THE EDITOR
Approximately 30% of ambulatory older adults fall yearly [1]; 5% to 10% are seriously injured [2]. Vitamin D deficiency increases body sway and decreases muscle mass and strength, increasing falls risk [3, 4]. Vitamin D supplementation reduces falls by 11% to 22% [5, 6]. To our knowledge, no studies report characteristics of ambulatory fallers associated with meeting the vitamin D recommended adequate intake (RAI). We report patient characteristics associated with vitamin D intake in a falls study.
METHODS
We analyzed data from Safety Assessment for Elders (SAFE), a randomized, controlled study of multifactorial interventions to reduce falls (ClinicalTrials.org identifier NCT00140322). Eligible subjects were adults ages ≥65 years at high falls risk [7]. At baseline and study end, researchers visited subjects’ homes to examine all medication and supplement bottles and record vitamin D intake.
Participants were randomized to receive mailed home safety information or a multifactorial intervention designed to decrease falls risk. In the active arm, subjects with a daily vitamin D intake <800 IU were asked to increase intake to ≥800 IU/day [8]. Participants and their physicians received letters instructing them how to increase vitamin D intake. Participants were called monthly for eleven months to encourage adherence with recommendations.
Study outcomes were the rates and patient characteristics (Table) associated with meeting the age-specific vitamin D RAI of 400 IU (ages 51–70 years or 600 IU (ages ≥71 years) per day [9] at study entry and study end. Subjects with unknown vitamin D intake at baseline (n=18 of 500) were excluded. Forty-five of 482 subjects had missing data at one year; these individuals were similar to the remaining subjects (P > .05, candidate variables).
Table 1.
μCharacteristics Associated with Meeting the Vitamin D Recommended Adequate Intake (RAI)* at Baseline
| Characteristic | All subjects (N=482) | Does Not Meet RAI (n=347) | Meets RAI (n=135) | P-Value |
|---|---|---|---|---|
| λAge, mean±SD | 79.2±7.6 | 80.3±6.9 | 76.4±8.4 | <0.001 |
| Female, n (%) | 361 (74.9) | 244 (70.3) | 117 (86.7) | .003 |
| Caucasian race, n (%) | 469 (97.3) | 339 (97.7) | 130 (96.3) | .57 |
| Number of concomitant medications, mean±SD | 5.5±3.3 | 5.5±3.4 | 5.4±3.0 | .88 |
| Homebound, n (%)≅ | 59 (12.2) | 46 (13.3) | 13 (9.6) | .35 |
| Falls in past year, mean±SD | 2.6±3.5 | 2.6±3.7 | 2.6±2.6 | .81 |
| Fall with injury, n (%) | 206 (42.7) | 140 (40.3) | 66 (48.9) | .11 |
| Prior adult fracture, n (%) | 190 (39.4) | 127 (36.6) | 63 (46.7) | .05 |
| Prior hip fracture, n (%) | 42 (8.7) | 28 (8.1) | 14 (10.4) | .53 |
| Regular exercise, n (%)⊥ | 265 (55.0) | 187 (53.9) | 78 (57.8) | .50 |
| Health related quality of life according to the Medical Outcomes Study 12-item Short Form Survey, mean±SD | ||||
| νPhysical Component Summary | 39.6±10.3 | 39.0±10.1 | 41.1±10.7 | .04 |
| νMental Component Summary | 53.6±9.5 | 53.5±9.6 | 53.7±9.3 | .82 |
| Education, years, mean±SD | 14.3±3.9 | 14.2±3.9 | 14.4±4.0 | .71 |
| Calcium supplement use, n (%) | 326 (67.6) | 199 (57.3) | 127 (94.1) | <0.001 |
The RAI is 400λIU/d for people aged 51 to 70 and 600λIU/d for people aged 70 and older.
Unable to walk outside and shop for groceries.
Walking for exercise in the previous 2 weeks.
SD=standard deviation.
All data were analyzed using Analyze-It software (Leeds, UK) and summarized using the mean ± standard deviation (SD) or percentage points. Continuous study data were parametric, allowing analysis by independent sample t-test. Chi-square tests examined proportions. In all cases, a two-sided P value < .05 determined significant findings.
RESULTS
Vitamin D intake was recorded at baseline (n=482) and study end (n=446) from 500 subjects enrolled. Baseline demographics (Table) included a mean age of 79 ± 8 years and predominance of female (75%), Caucasian (97%) subjects. Participants reported an average of three falls yearly and a mean vitamin D supplement intake of 370 ± 320 IU daily. Only 28% of all subjects met the vitamin D RAI at study entry, increasing to 37% at study end (P = .007).
Five characteristics associated with greater likelihood of meeting the age-specific vitamin D RAI at baseline (Table). Participants meeting the RAI (n=135) were younger (76 ± 8 versus 80 ± 7, P < .001), more likely to be women (87% versus 70%, P = .003), suffer prior fracture (47% versus 37%, P = .05) and take calcium supplements (94% versus 57%, P < .001). Individuals who met the vitamin D RAI had better SF12 physical function scores (41 ± 11 vs. 39 ± 10, P = 0.04).
Subjects with known vitamin D intake at both entry and study end (n=437) increased vitamin D intake during participation (350 ± 300 IU to 410 ± 350 IU daily, P = .009). Two characteristics associated with increased intake. Subjects randomized to active falls interventions (33% versus 17%, P < .001) and those reporting regular exercise (29% versus 20%, P = .04) were statistically more likely to increase vitamin D intake during the one-year study.
DISCUSSION
Vitamin D is a safe, inexpensive strategy to reduce falls and associated medical costs. This study shows older fallers have a low rate of meeting the vitamin D RAI, especially men, older individuals, those without prior fracture and people avoiding calcium supplements. Patients and providers need greater education on the import of vitamin D for prevention of falls and fractures. Written instructions and regular phone follow-up appear to increase vitamin D intake in elderly fallers. This finding, if verified in additional studies, may prove an effective public health strategy to decrease falls in older adults.
References
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