Vitamin D Inadequacy is Highly Prevalent Among North American Women Treated for Osteoporosis MF Holick1, ES Siris2, N Binkley3, MK Beard4, AA Khan5, JT Katzer6, E Chen6, AE de Papp6 1Boston University Medical Center, Boston, MA, 2Columbia University, NY, NY, 3University of Wisconsin, Madison, WI, 4University of Utah, Salt Lake City, UT, 5McMaster University, Hamilton, ON, 6Merck & Co., Inc., West Point, PA Table 1. BASELINE CHARACTERISTICS INTRODUCTION RESULTS Characteristics Total N = 1536 Age (years) Mean (SD) 71.1 (9.9) Race n (%) Caucasian Black Asian Other 1406 (91.5) 41 (2.7) 32 (2.1) 18 (1.2) Body Mass Index (kg/m2) Mean (SD) 26.4 (5.5) Geographic Region by Latitude n (%) ≥42º 35º - 41º <35º 532 (34.6) 642 (41.8) 362 (23.6) Vitamin D Supplementation n (%) <400 IU Daily ≥400 IU Daily 622 (40.5) 914 (59.5) T-score Mean (SD) Lumbar Spine Total Hip -1.8 (1.5) -1.7 (1.0) SD=standard deviation. IU=international units. Vitamin D inadequacy can lead to alterations in calcium and and phosphate homeostasis, secondary hyperparathyroidism, bone loss, osteoporosis, and an increase risk of fractures. Vitamin D inadequacy may be overlooked by clinicians, potentially leading to a lack of adequate vitamin D supplementation in patients treated for osteoporosis. This study was designed to evaluate the distribution of serum 25(OH)D concentrations in postmenopausal women currently receiving antiresorptive or anabolic therapies for the treatment of osteoporosis. Vitamin D Inadequacy (<30 ng/ml) Prevalence by Latitude N = 259 / 532 (48.7%) N = 342 / 642 (53.3%) N = 198 / 362 (54.7%) STUDY DESIGN Cross-sectional observational study conducted from November 2003 to March 2004 1554 postmenopausal women from 61 sites in North America Sites evenly distributed across geographic regions by latitude (>42ºN, Boston, MA, between 35-42ºN, and below 35ºN, Memphis,TN) Informed consent and past medical history obtained A single blood sample was collected to assess 25(OH)D, calcium, parathyroid hormone (PTH), phosphate, albumin, creatinine (Cr), magnesium, alkaline phosphatase, and total bilirubin concentrations A 28 item questionnaire was completed by all study subjects Sites also in Alaska and Hawaii P = NS for test of trend STATISTICAL METHODS Vitamin D Inadequacy (<30 ng/ml): Age Subgroups 1536 subjects had valid results of serum 25(OH)D Distribution (mean, standard deviation, median, range, etc.) of serum 25(OH)D was determined, and percent of patients with serum 25(OH)D below various cutpoints was evaluated Univariate logistic regression models used to assess association between potential risk factors and low 25(OH)D [<30 ng/mL (75 nmol/L)] Pearson’s correlation coefficient was calculated to assess the relationship between serum 25(OH)D and serum PTH INCLUSION CRITERIA Postmenopausal women living in North America, currently on antiresorptive or anabolic therapies to treat or prevent osteoporosis Subjects were >55 years of age and postmenopausal for a minimum of 2 years Subjects were required to have taken medication to treat or prevent osteoporosis for a minimum of 3 months, including: alendronate, calcitonin, etidronate, raloxifene, risedronate, or teriparatide ENDPOINTS CONCLUSIONS 25(OH)D concentrations were determined using the Nichols Advantage chemiluminescent assay (normal range 10-68 ng/mL) Various cutpoints of serum 25(OH)D were used to define vitamin D inadequacy (25(OH)D <9 ng/mL, <15 ng/mL, <20 ng/mL, <25 ng/mL, or <30 ng/mL) Demographic, dietary, environmental (sun exposure) and health-related variables assessed by subject completed questionnaire The percent of subjects with biochemical evidence of secondary hyperparathyroidism was determined SUMMARY Vitamin D inadequacy is highly prevalent amongst postmenopausal women receiving therapy for osteoporosis. There was a significantly higher prevalence of vitamin D inadequacy among subjects taking less than 400 IU of vitamin D supplementation daily (63%) compared with those who took at least 400 IU daily (45%) (Figure 2). 206 (16.5%) of subjects had biochemical evidence of secondary hyperparathyroidism. There was a significant (p<0.001) negative correlation between serum PTH and 25(OH)D; r =-0.3. Multiple risk factors were associated with Vitamin D inadequacy (p<0.05), including some which are easily modifiable (Table 2). Up to 52% of North American women currently receiving treatment for osteoporosis have suboptimal 25(OH)D levels. The prevalence rates of Vitamin D inadequacy are even higher (63%) in those reporting less than 400 IU of Vitamin D supplementation daily. A high prevalence of Vitamin D inadequacy was seen across all age groups and geographic regions studied. We advocate the use of Vitamin D supplementation and patient counseling regarding the importance of Vitamin D in all postmenopausal women with osteoporosis.