The role of vitamin D in general health maintenance is a topic of increasing interest and importance in the medical community. Not only has vitamin D deficiency been linked to a myriad of nonorthopedic maladies, including cancer, diabetes, and cardiovascular disease, but it has demonstrated an adverse effect on musculoskeletal health.1 Authors have found a correlation between vitamin D deficiency and muscle weakness, fragility fractures, and, most recently, fracture nonunion.1 Despite the detrimental effects of vitamin D deficiency on musculoskeletal and general health, evidence exists that vitamin D deficiency is surprisingly prevalent.2 This deficiency is known to be associated with increasing age, but recent studies have also found alarming rates of deficiency in younger populations.3,4
Although there has been some discussion regarding optimal serum levels of 25-hydroxyvitamin D, most experts have defined vitamin D deficiency as a 25-hydroxyvitamin D level of 20 ng/mL or less and insufficiency as 21 to 32 ng/mL.5 Hollis and Wagner5 found increased serum parathyroid hormone and bone resorption and impaired dietary absorption of calcium when 25-hydroxyvitamin D levels were under 32 ng/mL. Given these data, a 25-hydroxyvitamin D level of 21 to 32 ng/mL (52-72 nmol/L) can be considered as indicating a relative insufficiency of vitamin D, and a level of 20 ng/mL or less can be considered as indicating vitamin D deficiency.
Vitamin D plays a vital role in bone metabolism and has been implicated in increased fracture risk and in fracture healing ability. Therefore, documenting the prevalence of vitamin D deficiency in patients with trauma is the first step in raising awareness among orthopedic traumatologists and further developing a screening-and-treatment strategy for vitamin D deficiency in these patients. Steele and colleagues6 retrospectively studied 44 patients with high- and low-energy fractures and found an almost 60% prevalence of vitamin D insufficiency. If vitamin D insufficiency is this prevalent, treatment protocols for patients with fractures may require modifications that include routine screening and treatment for low vitamin D levels.
After noting a regular occurrence of hypovitaminosis D in our patient population (independent of age, sex, or medical comorbidities), we conducted a study to determine the prevalence of vitamin D deficiency in a large orthopedic trauma population.
Patients and Methods
After obtaining Institutional Review Board approval for this study, we retrospectively reviewed the charts of all patients with a fracture treated by 1 of 4 orthopedic traumatologists within a 21-month period (January 1, 2009 to September 30, 2010). Acute fracture and recorded 25-hydroxyvitamin D level were the primary criteria for study inclusion. Given the concern about vitamin D deficiency, it became common protocol to check the serum 25-hydroxyvitamin D levels of patients with acute fractures during the review period. Exclusion criteria were age under 18 years and presence of vitamin D deficiency risk factors, including renal insufficiency (creatinine level, ≥2 mg/dL), malabsorption, gastrectomy, active liver disease, acute myocardial infarction, alcoholism, anorexia nervosa, and steroid dependency.
During the period studied, 1830 patients over age 18 years were treated by 4 fellowship-trained orthopedic traumatologists. Of these patients, 889 (487 female, 402 male) met the inclusion criteria. Mean age was 53.8 years. Demographic data (age, sex, race, independent living status, comorbid medical conditions, medications) were collected from the patients’ medical records. Clinical data collected were mechanism of injury, fracture location and type, injury date, surgery date and surgical procedure performed (when applicable), and serum 25-hydroxyvitamin D levels.
Statistical Methods
Descriptive statistics (mean, median, mode) were calculated. The χ2 test was used when all cell frequencies were more than 5, and the Fisher exact probability test was used when any cell frequency was 5 or less. Prevalence of vitamin D deficiency and insufficiency was calculated in multiple patient populations. Patients were analyzed according to age and sex subgroups.
Definitions
Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D level of 20 ng/mL or less and insufficiency as 21 to 32 ng/mL.2 As the serum test was performed independent of the investigators and with use of standard medical laboratory protocols and techniques, there should be no bias in the results. We had intended to have all patients undergo serum testing during the review period because that was our usual protocol. However, test results were available for only 889 (49%) of the 1830 patients with orthopedic trauma during the review period. Although a false-positive is theoretically possible, this series of orthopedic trauma patients is the largest in the literature and therefore should be more accurate than the previously reported small series.