Prevalence of Low Vitamin D Levels in Patients With Orthopedic Trauma

Results

There were no significant (P < .05) age or sex differences in prevalence of vitamin D deficiency or insufficiency in our patient population. Overall prevalence of deficiency/insufficiency was 77.39%, and prevalence of deficiency alone was 39.03% (Table 1).

Women in the 18- to 25-year age group had a lower prevalence of deficiency (25%; P = .41) and insufficiency (41.7%; P = .16) than women in the other age groups (Table 3).

Discussion

We conducted this study to determine the prevalence of vitamin D deficiency in a large population of patients with orthopedic trauma. Results showed that vitamin D deficiency and insufficiency were prevalent in this population, which to our knowledge is the largest studied for vitamin D deficiency. In a 6-month study of 44 fractures, Steele and colleagues⁶ found an overall 60% rate of deficiency/insufficiency. Although their investigation is important—it was the first of its kind to evaluate patients with various fracture types, including those with high-energy causes—its numbers were small, and the period evaluated (June 1, 2006 to February 1, 2007) was short (8 months). Use of that time frame may have led to an underestimate of the prevalence of vitamin D deficiency, as vitamin D levels are higher in late summer because of increased sun exposure. Our study of 889 patients over 21 months allowed for seasonal variability of vitamin D levels. We did not notice a specific difference in patients who were treated during winter vs summer. Furthermore, our 77% prevalence of vitamin D insufficiency and 39% prevalence of vitamin D deficiency indicate how widespread low vitamin D levels are in a large Midwestern orthopedic trauma population. In the Pacific Northwest, Bee and colleagues⁷ studied seasonal differences in patients with surgically treated fractures and found an average difference of 3 ng/mL between winter and summer serum levels. However, the real issue, which should not be overlooked, is that the average 25-hydroxyvitamin D level was under 30 ng/mL in both cohorts (26.4 ng/mL in winter vs 29.8 ng/mL in summer). The emphasis should be that both levels were insufficient and that seasonal variance does not really change prevalence.

With use of the current definitions, it has been estimated that 1 billion people worldwide have vitamin D deficiency or insufficiency, with the elderly and certain ethnic populations at higher risk.^8-10Vitamin D deficiency is a common diagnosis among elderly patients with hip fractures. According to various reports, 60% to 90% of patients treated for hip fractures are deficient or insufficient in vitamin D.^8,9Hypovitaminosis D has also been noted in medical inpatients with and without risks for this deficiency.² Surprisingly, low vitamin D levels are not isolated to the elderly. In Massachusetts, Gordon and colleagues¹¹ found a 52% prevalence of vitamin D deficiency in Hispanic and black adolescents. Nesby-O’Dell and colleagues¹⁰ found that 42% of 15- to 49-year-old black women in the United States had vitamin D deficiency at the end of winter. Bogunovic and colleagues¹² noted 5.5 times higher risk of low vitamin D levels in patients with darker skin tones. Although vitamin D deficiency has been linked to specific races, it frequently occurs in lower-risk populations as well. Sullivan and colleagues⁴ found a 48% prevalence of vitamin D deficiency in white preadolescent girls in Maine. Tangpricha and colleagues³ reported a 32% prevalence of vitamin D deficiency in otherwise fit healthcare providers sampled at a Boston hospital. Bogunovic and colleagues¹² also showed that patients between ages 18 years and 50 years, and men, were more likely to have low vitamin D levels.

Establishing the prevalence of hypovitaminosis D in orthopedic trauma patients is needed in order to raise awareness of the disease and modify screening and treatment protocols. Brinker and O’Connor¹³ found vitamin D deficiency in 68% of patients with fracture nonunions, which suggests that hypovitaminosis D may partly account for difficulty in achieving fracture union. Bogunovic and colleagues¹² found vitamin D insufficiency in 43% of 723 patients who underwent orthopedic surgery. Isolating the 121 patients on the trauma service revealed a 66% prevalence of low vitamin D levels. Our 77% prevalence of low vitamin D levels in 889 patients adds to the evidence that low levels are common in patients with orthopedic trauma. Understanding the importance of vitamin D deficiency can be significant in reducing the risk of complications, including delayed unions and nonunions, associated with treating orthopedic trauma cases.

Although our study indicates an alarming prevalence of insufficient vitamin D levels in our patient population, it does not provide a cause-and-effect link between low serum 25-hydroxyvitamin D levels and risk of fracture or nonunion. However, further investigations may yield clinically relevant data linking hypovitaminosis D with fracture risk. Although we did not include patients with nonunion in this study, new prospective investigations will address nonunions and subgroup analysis of race, fracture type, management type (surgical vs nonsurgical), injury date (to determine seasonal effect), and different treatment regimens.

The primary limitation of this study was its retrospective design. In addition, though we collected vitamin D data from 889 patients with acute fracture, our serum collection protocols were not standardized. Most patients who were admitted during initial orthopedic consultation in the emergency department had serum 25-hydroxyvitamin D levels drawn during their hospital stay, and patients initially treated in an ambulatory setting may not have had serum vitamin D levels drawn for up to 2 weeks after injury (the significance of this delay is unknown). Furthermore, the serum result rate for the overall orthopedic trauma population during the review period was only 49%, which could indicate selection bias. There are multiple explanations for the low rate. As with any new protocol or method, it takes time for the order to become standard practice; in the early stages, individuals can forget to ask for the test. In addition, during the review period, the serum test was also relatively new at our facility, and it was a “send-out” test, which could partly account for the lack of consistency. For example, some specimens were lost, and, in a number of other cases, excluded patients mistakenly had their 1,25-hydroxyvitamin D levels measured and were not comparable to included patients. Nevertheless, our sample of 889 patients with acute fractures remains the largest (by several hundred) reported in the literature.

From a practical standpoint, the present results were useful in updating our treatment protocols. Now we typically treat patients only prophylactically, with 50,000 units of vitamin D₂ for 8 weeks and daily vitamin D₃ and calcium until fracture healing. Patients are encouraged to continue daily vitamin D and calcium supplementation after fracture healing to maintain bone health. Compliance, however, remains a continued challenge and lack thereof can potentially explain the confusing effect of a supplementation protocol on the serum 25-hydroxyvitamin D level.¹⁴ The only patients who are not given prophylactic treatment are those who previously had been denied it (patients with chronic kidney disease or elevated blood calcium levels).

Vitamin D deficiency and insufficiency are prevalent in patients with orthopedic trauma. Studies are needed to further elucidate the relationship between low vitamin D levels and risk of complications. Retrospectively, without compliance monitoring, we have not seen a direct correlation with fracture complications.¹⁵ Our goal here was to increase orthopedic surgeons’ awareness of the problem and of the need to consider addressing low serum vitamin D levels. The treatment is low cost and low risk. The ultimate goal—if there is a prospective direct correlation between low serum vitamin D levels and complications—is to develop treatment strategies that can effectively lower the prevalence of low vitamin D levels.

Am J Orthop. 2016;45(7):E522-E526. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.