VITAMIN D IS ESSENTIAL for maintaining calcium

904 ORIGINAL ARTICLE Vitamin D Deficiency and Osteoporosis in Rehabilitation Inpatients Leonid M. Shinchuk, MD, Leslie Morse, DO, Nadia Huancahuari, Seth Arum, MD, Tai C. Chen, PhD, Michael F. Holick, MD, PhD ABSTRACT. Shinchuk LM, Morse L, Huancahuari N, Arum S, Chen TC, Holick MF. Vitamin D deficiency and osteoporosis in rehabilitation inpatients. Arch Phys Med Rehabil 2006;87:904-8. Objective: To determine vitamin D status and bone mineral density (BMD) in patients admitted to a subacute rehabilitation facility. Design: Cross-sectional cohort study. Setting: Subacute rehabilitation facility. Participants: Fifty-three community-dwelling patients admitted from June through February 2005. Interventions: Not applicable. Main Outcome Measures: BMD, 25-hydroxyvitamin D (25[OH]D), C-telopeptide (CTX), osteocalcin, and dietary milk intake. Results: Prevalence of vitamin D deficiency (25[OH]D 20ng/mL) was 49.1%, while a total of 83% of patients were either vitamin D deficient or insufficient (25[OH]D 30ng/ ml). The prevalence of osteopenia (T score, 1) was 52.8%; osteoporosis (T score, 2.5) was 17.0%. CTX (bone resorption marker) was elevated in 60.4% of patients. Osteocalcin (bone formation marker) was elevated in 13.2% of patients. Measurements of bone resorption and formation positively correlated (R 2.22) indicating increased bone remodeling. Conclusions: Vitamin D deficiency and osteopenia and osteoporosis were highly prevalent in patients admitted for rehabilitation. Elevated bone resorption and remodeling were evident. This could be due to vitamin D deficiency that should be corrected before antiresorptive therapy is considered. The study emphasizes the need for vigilance for vitamin D status and BMD testing in patients admitted to rehabilitation facilities. Key Words: Bone density; Osteoporosis; Rehabilitation; Vitamin D deficiency. 2006 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation From the Departments of Physical Medicine and Rehabilitation (Shinchuk, Morse) and Medicine (Huancahuari, Arum, Chen, Holick), Boston University Medical Center, Boston, MA. Presented to the American Academy of Physical Medicine and Rehabilitation, October 28, 2005, Philadelphia, PA. Supported by the National Institutes of Health (grant no. M01RR 00533). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Correspondence to Michael F. Holick, MD, PhD, Boston University School of Medicine, 715 Albany St, #M1013, Boston, MA 02118, e-mail: MFHolick@BU.edu. Reprints are not available from the author. 0003-9993/06/8707-10592$32.00/0 doi:10.1016/j.apmr.2006.03.009 VITAMIN D IS ESSENTIAL for maintaining calcium and phosphorus homeostasis, and optimizing bone health. The active form of vitamin D, 1,25-dihydroxyvitamin D (1,25[OH] 2 D), acts on specific nuclear receptors to increase calcium absorption from the small intestine and to regulate bone turnover. 1 Vitamin D deficiency leads to secondary hyperparathyroidism and, if not treated, to development of osteoporosis with subsequent increase in fracture risk. 2-4 Additionally, 1,25(OH) 2 D binds to receptors on skeletal muscles. 5-8 Recent studies 9-11 showed strong association between higher serum vitamin D concentrations and muscle strength, physical activity, and reduced falls in elderly. Vitamin D can be obtained from diet or synthesized in the skin under appropriate intensity and duration of ultraviolet radiation. 12,13 Vitamin D is biologically inert and must undergo 2 successive hydroxylations in the liver and kidney to become the biologically active 1,25(OH) 2 D. 1 Factors that interfere with vitamin D intake, absorption, synthesis, or metabolism result in vitamin D deficiency. Advanced age, nonwhite ethnicity, poor dietary intake, increased body mass index (BMI), inadequate sun exposure, northern latitude, and medications that impair vitamin D activation or accelerate clearance are known risk factors for vitamin D deficiency. 14 However, standard clinical risk factors are poor predictors of vitamin D status. 15 The prevalence of vitamin D deficiency in communitydwelling elderly is estimated to be between 25% and 54%. 16 The prevalence of vitamin D deficiency in medical inpatients was reported around 57%. 15 Untreated, vitamin D deficiency will lead to development of osteopenia and osteoporosis defined by World Health Organization (WHO) as bone mass 1 and 2.5 standard deviations (SDs) below the sex-controlled young adults, respectively. In the United States, 40% of women over the age of 50 have osteopenia and 7% suffer from osteoporosis. 17 Vitamin D deficiency is also highly prevalent in men. In the United States, 3.5 million men over the age of 65 have osteopenia and 1.5 million suffer from osteoporosis. 18 Osteoporosis is a silent disease with the first manifestation being development of pathologic fracture. There are approximately 1.3 million osteoporotic fractures each year in the United States with an estimated cost of $13.8 billion in 1995. 19 Patients who require a subacute rehabilitation stay after an acute hospitalization possess multiple risk factors for vitamin D deficiency and are at risk of osteopenia and osteoporosis. Frequently, these patients are older, medically complex, and suffer from reduced mobility and poor nutritional status. The goal of this study was to determine vitamin D status and the prevalence of vitamin D deficiency in this vulnerable group of patients. In addition, we determined the prevalence of osteopenia and osteoporosis, ascertained factors related to vitamin D deficiency and low bone mineral density (BMD), and determined bone resorption and formation activity in these patients.

VITAMIN D DEFICIENCY AND OSTEOPOROSIS IN REHABILITATION, Shinchuk 905 METHODS Study Participants From June 2004 to February 2005, we recruited a cohort of inpatients admitted to a subacute rehabilitation facility at Boston Medical Center to participate in the study. Subjects were excluded if they were younger than 21 years old, pregnant, not proficient in English, or were taking vitamin D or calcium supplementation. The study was approved by the institutional review board and signed informed consent was obtained from each subject prior to enrollment. Study Conduct Subjects attended a single study visit at the General Clinical Research Center where demographic information, height, and weight were recorded. A dual x-ray absorptiometry (DXA) scan was performed on a QDR 4500 Hologic bone densitometer. a A single blood sample was collected to assess 25(OH)D, osteocalcin, and C-telopeptide (CTX). A questionnaire was administered to ascertain pertinent medical, dietary, and medication history. Laboratory Studies We determined serum 25(OH)D using a Nichols Advantage Specialty System b with a 6.4% to 14.5% interassay coefficient of variation (CV). The normative range for adults is 20 to 100ng/mL. We measured CTX utilizing the Serum CrossLaps ELISA c kit. The detection limit was.01ng/ml. The intra- and interassay CV ranges from 5.0% and 8.0%, respectively. Mean observed reference values for premenopausal women, postmenopausal women, and men are 0.32 0.16, 0.51 0.26, and 0.33 0.19ng/mL, respectively. We measured osteocalcin with a Nichols Advantage system. The assay has sensitivity of 0.1ng/mL, and the intra- and interassay CV ranges from 4.6% to 5.3% and 7.3% to 9.5%, respectively. The reference values of osteocalcin for premenopausal women and men range from 0.5 to 7.0ng/mL and 1.1 to 7.2ng/mL, respectively. Outcome Measures The major outcome measures include vitamin D inadequacy, bone resorption and formation activity, prevalence of osteopenia and osteoporosis, and milk consumption data. Various cut-points of serum 25(OH)D were used to define vitamin D inadequacy ( 9, 15, 20, 25, 30ng/mL). An increase in bone resorption activity was defined as CTX levels above the normative range provided by the manufacturer for premenopausal women, postmenopausal women, and men. An increase in bone formation was defined as osteocalcin levels above the normative range provided by the manufacturer for premenopausal women and men. The normative range for osteocalcin for postmenopausal women is unknown, so the value for premenopausal women was used instead, which may have led to underestimation of the results. Osteopenia and osteoporosis were defined based on the WHO classification. Inadequate milk consumption was defined as self-reported intake of less than 1 glass of milk a day prior to hospitalization. Statistical Analysis We calculated the distribution of serum 25(OH)D and the percentage of patients below 9, 15, 20, 25, and 30ng/mL and associated 95% confidence intervals (CIs). Prevalence of vitamin D deficiency and associated CIs by sex and race were ascertained. The Pearson correlation coefficient was calculated to assess the relation between serum 25(OH)D, age, and BMI. We calculated the prevalence of osteopenia, osteoporosis, increased CTX and osteocalcin, and milk consumption with associated 95% CIs. The Pearson correlation coefficient was calculated to assess the relation between CTX and osteocalcin. We performed group comparisons by sex and race for serum 25(OH)D less than 20ng/mL and less than 30ng/mL, osteopenia, osteoporosis, and inadequate milk consumption based on chi-square or Fisher exact tests as appropriate. A P value of.05 or less was considered statistically significant. All analyses were performed using SAS statistical software. d RESULTS Participants Sixty-one patients met inclusion criteria. Eight (13.1%) patients were excluded from the study (3 patients withdrew consent, 4 patients did not provide sufficient material for serum measurements, 1 patient was discharged prior to completion of the study). Fifty-three (86.9%) patients provided a blood sample for determination of serum 25(OH)D, osteocalcin, and CTX, underwent DXA scan, and completed the questionnaire. Subjects mean age was 60.2 14.1 years and included 30 (56.6%) men, 23 (43.4%) women, 29 (54.7%) whites, 20 (37.7%) African Americans, 2 (5.7%) Hispanics, and 1 (1.9%) Asian. Forty-nine (92.5%) patients were ambulatory prior to admission, 3 (5.7%) patients were housebound, and 1 (1.9%) patient was homeless. None of the patients was a nursing home resident. Patients demographics are summarized in table 1. The length of acute hospitalization prior to transfer to the transitional care unit was 7.2 5.3 days. Forty-three (81.1%) patients were transferred from a surgical service (23 [43.4%] patients after joint replacement, 8 [15.1%] patients after other orthopedic procedure, 12 [22.6%] patients after surgical nonorthopedic procedure). Ten (18.9%) patients were transferred from a medical service. Three (5.7%) patients were receiving therapy with glucocorticoids, 3 (5.7%) were taking anticonvulsant agents (phenytoin, phenobarbital, or carbamazepine), 1 (1.9%) patient was receiving both glucocorticoid and anticonvulsant agents, and none of the patients were taking rifampin. Table 1: Demographics Characteristic Total (N 53) Age (y) 60.2 14.1 Sex Male 30 (56.6) Female 23 (43.4) Ethnicity White 29 (54.7) Black 20 (37.7) Hispanic 3 (5.7) Asian 1 (1.9) Other 0 (0.0) Residential and functional status Ambulatory 49 (92.5) Housebound 3 (5.7) Nursing home resident 0 (0.0) Homeless 1 (1.9) BMI (kg/m 2 ) 29.0 6.5 NOTE. Values are mean SD or n (%).

906 VITAMIN D DEFICIENCY AND OSTEOPOROSIS IN REHABILITATION, Shinchuk Prevalence ± 95% Confidence Interval 100% 80% 60% 40% 20% 0% All Subjects White Non-white <9ng/mL <15ng/mL <20ng/mL <25ng/mL <30ng/mL Cutoff Points for Serum-25(OH)D Fig 1. Prevalence of vitamin D inadequacy in all subjects, white and nonwhite patients. The percentage of subjects with serum 25(OH)D concentrations below predefined cutoffs of <9, <15, <20, <25, and <30ng/mL. Prevalence of Low Serum 25(OH)D Several cutpoints were used to describe the prevalence of vitamin D inadequacy in the study population (fig 1). We found that 83.0% (95% CI, 72.9% 93.1%) of subjects had a serum 25(OH)D less than 30ng/mL and 49.1% (95% CI, 35.6% 62.6%) had values less than 20ng/mL. Vitamin D deficiency ( 20ng/mL) was equally present in men (46.7%) and women (52.2%). The prevalence of vitamin D deficiency was 41.4% in white patients and 58.3% in nonwhite patients (see fig 1). There was no difference in the prevalence of vitamin D deficiency during seasonal peak (June September) and the other months (October February), 51.7% and 45.8%, respectively. Age and BMI did not correlate with 25(OH)D (r 2.005 and r 2.097, respectively). Prevalence of Osteopenia and Osteoporosis Exactly 53.3% (95% CI, 35.4% 71.2%) of men and 52.2% (95% CI, 31.8% 72.6%) of women had osteopenia (T score of 1.0) and 20% (95% CI, 5.7%.34.3%) of men and 13% (95% CI, 0% 26.7%) of women had osteoporosis (T score 2.5) (fig 2). Prevalence of osteopenia in white and nonwhite patients was 51.7% and 54.2%, respectively, while prevalence of osteoporosis was 6.9% and 29.2%, respectively (see fig 2). Markers of Bone Resorption and Formation In this patient population, 60.4% (95% CI, 47.2% 73.6%) of patients had an increase in bone resorption (CTX.52ng/mL in men,.48ng/ml in premenopausal women,.77ng/ml in postmenopausal women), and 13.2% (95% CI, 4.1% 22.3%) of patients had an increase in bone formation (osteocalcin 7.0ng/mL in women; 7.2ng/mL in men). Bone formation and resorption activity correlated weakly (r 2.22), indicating an increase in bone remodeling. Milk Intake Forty-nine percent (95% CI, 35.5% 62.5%) of patients reported consuming less than 1 glass of milk a day prior to hospitalization (53.3% men, 47.8% women) while 13.2% (95% CI, 4.1% 22.3%) consumed more than 2 glasses a day (10.0% men, 17.4% women). Inadequate milk consumption was more prevalent in African Americans (66.7%) than in whites (38.0%) (P.027). DISCUSSION In this study of 53 patients admitted to a rehabilitation facility after an acute hospitalization, we found a high prevalence of vitamin D deficiency in both male and female inpatients. There was no statistical difference in vitamin D deficiency between white and nonwhite patients; even so, there was a tendency for a higher prevalence of vitamin D deficiency in the nonwhite cohort. Given a relatively short duration of preceding acute hospitalization for the majority of patients, the observed prevalence of vitamin D deficiency is likely a premorbid characteristic of the group because the serum half-life for 25(OH)D is approximately 2 weeks. 14 Interestingly, neither age nor BMI correlated with 25(OH)D level (r 2.005 and r 2.097, respectively). One explanation might be that the younger or more overweight patients who require rehabilitation stay prior to returning home are more medically affected and therefore more likely to develop vitamin D deficiency. Although previous studies described vitamin D deficiency in the general population and in medical inpatients, this study was aimed at evaluating a population of patients who require a subacute level rehabilitation stay after an acute hospitalization. This group of patients is at a higher risk to develop vitamin D deficiency given the reduced mobility and medical complexity that necessitated the rehabilitation stay. Clearly, little has been done to address vitamin D deficiency in these patients. As we reported previously, the prescription rate of vitamin D and/or calcium supplementation on admission to subacute rehabilitation was only about 12% indicating that this group remains an underdiagnosed and undertreated high-risk population for vitamin D deficiency. 20 Osteopenia and osteoporosis were highly prevalent on the subacute rehabilitation unit. Patients of both sexes and all races were equally affected. The combined prevalence of osteopenia and osteoporosis was 69.8%. It was previously reported that 25(OH)D levels correlate positively with BMD in young and older adults. 21 Additionally, vitamin D plays an important role in the maintenance of proximal muscle strength and reduction of falls. 22-25 Long-term vitamin D and calcium supplementation was shown to reduce the risk of nonvertebral fractures by 32% to 58%. 26,27 Bischoff et al 28 demonstrated in a randomized controlled trial that daily vitamin D and calcium supple- Prevalence of Osteopenia/Osteoporosis 100% 80% 60% 40% 20% 0% Male Female White Non-white T score < -1 Osteopenia T score as Defined by WHO T score < -2.5 Osteoporosis Fig 2. Prevalence of osteopenia and osteoporosis in male and female, white and nonwhite patients. T scores as defined by WHO (osteopenia T score < 1 SD; osteoporosis T score < 2.5 SD sexand race-controlled young adults).

VITAMIN D DEFICIENCY AND OSTEOPOROSIS IN REHABILITATION, Shinchuk 907 mentation improve musculoskeletal function (knee flexor and extensor strength, grip strength, and Timed Up & Go test) and reduces the risk of falls by 49% in long-term care facility patients. In a recently published meta-analysis, 29 the risk of falls among ambulatory or institutionalized older subjects with stable health was reduced by more than 20% compared with placebo. Thus, the combination of established osteopenia and osteoporosis and vitamin D deficiency puts the subacute rehabilitation inpatients in an especially high risk group of acquiring an osteoporotic fracture. Treatment with vitamin D and calcium supplementations will likely benefit the patients by improving their BMD and musculoskeletal function. We evaluated bone turnover activity by measurement of CTX and osteocalcin. There was significant bone resorption activity as evident by an increased CTX in 60.4% of the patients. At least 13.2% of patients had an increase in bone formation as evidenced by an increased osteocalcin. Overall, bone formation and bone resorption markers positively correlated (r 2.22), indicating an increase in bone remodeling. Exactly 58.5% of patients underwent an orthopedic intervention during the acute hospitalization. Similar results for markers of bone resorption (CTX) and formation (osteocalcin) were obtained evaluating subgroups with and without recent orthopedic procedures. Markers of bone resorption and formation were elevated in 54.8% and 9.7% of patients after an orthopedic procedure, respectively, and in 68.2% and 18.2% of patients, respectively, who did not have an orthopedic intervention. Bone turnover markers are much more sensitive to metabolic changes in bone than BMD. 30 It is unclear if substantially increased bone resorption activity in rehabilitation inpatients is due to a preceding period of relative inactivity during an acute hospitalization or to their baseline medical status and vitamin D deficiency. Caution must be taken when interpreting these results. Nevertheless, the changes in bone turnover markers are strong predictors of reduced fracture risk. 31 Casual exposure to sunlight provides most of the vitamin D requirement. 1 However, elderly people have decreased ability to synthesize vitamin D. Compared with young adults, a person older than 70 years of age produces less than 30% of the amount of vitamin D 3 when exposed to the same amount of sunlight. 32 Cutaneous synthesis of vitamin D also depends on the exposure to appropriate ultraviolet radiation, which depends on time of the day, season, and latitude. In Boston, MA (latitude 42 N), sunlight is incapable of producing vitamin D 3 in the skin between the months of November and February. 33 Thus, patients with limited mobility and the elderly who live in the northern latitudes must rely extensively on oral intake to cover the daily vitamin D requirement. The recommended daily oral vitamin D intake in the United States is 200IU for adults up to 50 years old, 400IU for adults 51 to 70, and 600IU for men and women over 71. 34 Milk is fortified with vitamin D. One glass provides approximately 100IU or from 17% to 50% of daily requirement depending on age. 35 Most dairy products, such as cheese and most yogurts, are not fortified with vitamin D. Thus, milk itself remains the main source of vitamin D. In our patient population, 49.1% of patients consumed less than 1 glass of milk a day. Dietary preferences or the higher prevalence of lactose intolerance with age, especially in the African-American populations, might explain these findings. However, it is clear that patients need to rely on other sources, either dietary or pharmacologic, to obtain adequate amounts of vitamin D. Although the relatively small sample size and the use of a single subacute site in Boston, MA, as a referral base limit the generalization of results, the high prevalence of vitamin D deficiency that we observed should alert physicians about hypovitaminosis D in rehabilitation inpatients at other medical centers. The study excluded patients who were taking vitamin D or calcium supplementations. These patients were representing less than 12% of all patients admitted, so excluding them did not significantly bias the reported prevalence of hypovitaminosis D. However, care must be taken to insure adequate vitamin D supplementation in that group as recent studies demonstrated high prevalence of vitamin D deficiency even in patients on pharmacologic therapy to treat osteoporosis and taking a multivitamin that contained vitamin D. 36 CONCLUSIONS Vitamin D deficiency and osteopenia and osteoporosis are highly prevalent in both men and women admitted for subacute rehabilitation after an acute hospitalization. Bone remodeling activity was elevated with a disproportional increase in bone resorption. This could be due to vitamin D deficiency that should be corrected before antiresorptive therapy is considered. This study emphasizes the need for vigilance for vitamin D status and BMD testing in patients admitted to rehabilitation facilities. References 1. Holick MF. Vitamin D: photobiology, metabolism, mechanism of action, and clinical applications. In: Favus MJ, editor. 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