Adherence to Vitamin D Supplementation in Elderly Patients After Hip Fracture

To the Editor: Vitamin D deficiency is frequently present in the elderly, especially in patients with hip fractures.1 It leads to increased bone turnover2,3 and could negatively influence bone status.3 Hip fractures account for about 10% of all fractures,4 and the rate of hip fractures increases by 1% to 3% per year.5 About 10% of these patients sustain repeat hip fractures.6 A second fracture, which may be in the same location, occurs in 6% of the cases within a 4-year period after the first fracture.7 According to one study,8 the occurence rate of two hip fractures in the course of an individual's life could reach 20%. Vitamin D and calcium supplements have been shown to reduce incidence of nonvertebral9 fractures and hip fractures by 30% in institutionalized patients.10 Patients with severe osteoporosis who sustain hip fractures are candidates for antiresorptive therapy with bisphosphonates (e.g., alendronate). Efficiency of alendronate therapy in reducing hip fractures was demonstrated in vitamin D replenished patients.10 Therefore, adherence to vitamin D supplementation is an important aspect of a therapeutic regimen for osteoporosis. We evaluated adherence to calcium and vitamin D supplements in hip fracture patients that were enrolled in a postsurgical follow-up program in the Metabolic Bone Diseases Unit after hospital discharge. Ninety-six consecutive patients, 77 women and 19 men, aged 50 to 90, mean age±standard deviation of 72.7±9, who underwent surgical repair of femoral neck fracture in the Department of Orthopedic Surgery were included in the study. Each patient received detailed explanation about osteoporosis, risk of future fractures, and the treatment of the disease. Compliance with the treatment was reevaluated 3 and 6 months after hospital discharge. Calcium and inorganic phosphate concentration in serum and serum levels of creatinine, albumin, and liver enzymes were performed using standard laboratory techniques (Hitachi 747, Roche, Mannheim, Germany). 25-hydroxy vitamin D (25(OH)D3) was assessed using 125I-radioimmunoassay (DiaSorin, Stillwater, MN) and intact parathyroid hormone using immunoradiometric assay (Nichols Institute Diagnostics, San Juan Capistrano, CA). Laboratory evaluation was performed in all patients during initial hospital stay and at two consecutive follow-up visits (3 and 6 months after hospital discharge). Treatment with 1,200 mg of calcium carbonate and 800 IU of vitamin D was started during the hospital stay. Hospital chart review was performed, and recommendation for calcium and vitamin D supplements was retrieved from the discharge letters. Student paired t test was used to compare variables between the visits. Chi-square test was performed to evaluate association between categorical variables. We found that 58 (60.4%) hip fracture patients had low 25(OH)D3 level at the time of hospitalization (Table 1) and four (4.2%) had secondary hyperparathyroidism. Three months after hospital discharge, only 23 (24.2%) patients had adhered to the recommended supplements, and 73 (75.8%) patients had stopped the treatment. Compliance rate was significantly higher in women than men (28.9% (22 women) vs 5.3% (1 man), P<.04). Hospital discharge letter analysis revealed that written recommendations about vitamin D and calcium supplements was included in 25% of the letters. Patients who had the recommendations were more compliant with supplementation (n=11, 45.8%) than those who did not (n=12, 16.6%, P=.002). Three months later, at the second visit to the Metabolic Bone Diseases Unit, 68 patients (70.8% of the entire group) were compliant with the treatment, whereas 49 of 73 previously noncompliant patients (66.9%) had adhered to the treatment. The mean 25(OH)D3 level was significantly higher at that visit (12.47±5.4 ng/mL before treatment vs 15.63±5.44 ng/L at the second visit, P<.0001). Parathyroid hormone (PTH) level did not change significantly in the whole group, whereas in the patients deficient in vitamin D, mean PTH level decreased from 45.5±26.5 ng/L to 38.5±20.34 ng/L (P=.048). In this study, we demonstrated that two-thirds of the elderly patients who sustained osteoporotic hip fracture had subnormal serum levels of 25(OH)D3 and most of the patients did not adhere to vitamin D and calcium supplementation recommendations after hospital discharge, in spite of the detailed information provided during hospitalization. Compliance with the treatment was higher in women than in men. Enrollment in the specially designed postsurgical follow-up program and written recommendations in the hospital discharge letter can significantly increase the adherence of elderly hip fracture patients to calcium and vitamin D supplementation recommendations.