Results
A summary of demographic information and data obtained at the initial pre-LT evaluation and LT is provided in Table 1 for the 127 study patients. Study information at the 4-month post-LT follow-up is provided in Table 2.
25-OH D levels at the initial evaluation, transplant, and 4-month post-LT follow-up are summarized in Table 3, along with the amount of vitamin D supplementation prescribed from initial evaluation to LT and from LT to 4 months post-LT. At initial evaluation, 107 of the 127 study patients (84%, 95% CI: 77–90%) had some degree of vitamin D deficiency. Of these patients, 66 (62%) were prescribed vitamin D supplementation.
Table 4 examines the association between the degree of vitamin D supplementation provided to deficient patients and change in vitamin D level. For the 105 patients with a vitamin D deficiency at initial evaluation and a vitamin D measurement at transplant, there was strong evidence of an increase in vitamin D level from initial evaluation to transplant with increased vitamin D supplementation (P<.0001). Results were somewhat similar for the 66 patients with a vitamin D deficiency at transplant and a vitamin D measurement at the 4-month follow-up, where there was evidence of an increased vitamin D level from transplant to 4-month follow-up with increased vitamin D supplementation (P = .003).
There was no evidence of an association between vitamin D deficiency category and functional status (P = .18) or physical capacity as assessed by the Karnofsky score (P = .42) at the 4-month follow-up (Table 2). We also found no evidence of an association between vitamin D levels at LT and either fracture or readmission rates within the 4 months following transplant. Similarly, there was no evidence of an association of vitamin D deficiency at transplant with worsening in spine, hip, or femoral neck BMD (data not shown). Patients who received basiliximab as induction immunosuppressive therapy had a significantly greater degree of worsening in femoral neck BMD (P = .044) but not spine (P = .28) or hip (P = .25) BMD (Table 5). Ten patients in our study developed biopsy-proven rejection, which was treated with high-dose intravenous corticosteroids.
We found statistically significant correlations between vitamin D and PTH at evaluation (r: −0.34, P<.001) and between vitamin D and PTH at the 4-month follow-up (r: −0.26, P = .019), as shown in Figures 1 and 2, respectively. Additionally, though not quite statistically significant, there were trends toward an association between PTH at evaluation and MELD score at listing (r: 0.17, P = .051) and also between PTH and creatinine at the 4-month follow-up (r: 0.19, P = .079). We did not find an association between albumin and PTH at initial evaluation (P = .88) or at the 4-month follow-up (P = .54). There also was no association between the amount of vitamin D supplementation given at initial evaluation (none, ≤400,000 IU, >400,000 IU) and change in PTH level from initial evaluation to 4-month follow-up (P = .49). Furthermore, we found no evidence of an association between vitamin D at evaluation and body mass index (BMI) as a continuous variable (P = .66) or BMI ≥30 (P = .78), or between PTH at evaluation and total bilirubin at listing (P = .77). For the negative correlations between vitamin D and PTH, we evaluated whether these may be the result of the potentially confounding influences of phosphorus, calcium, or creatinine in multivariable linear regression analysis. When adjusting for these 3 variables, the negative correlation between vitamin D and PTH at evaluation remained (P = .007), as did the negative correlation between vitamin D and PTH at the 4-month follow-up (P = .021). We also noted that as vitamin D levels increased in a given patient from initial evaluation to 4-month follow-up, PTH levels decreased significantly (Spearman's r: −0.22, P = .046).
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Figure 1.
Relationship between vitamin D and PTH levels at the time of transplant evaluation. PTH = parathyroid hormone.
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Figure 2.
Relationship between vitamin D and PTH levels at the 4-month posttransplant follow-up. PTH = parathyroid hormone.