You will be given a definition of a task first, then some input of the task.
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: Mineral bone disorder (MBD) is prevalent among chronic dialysis patients. However, relationship between different forms of vitamin D and fibroblast growth factor 23 (FGF-23) remains unclear in this population.', 'A multicenter hemodialysis cohort was assembled. We evaluated 25-OH-D and 1,25-(OH)2-D, vitamin D-binding protein, and FGF-23, in this cohort. Multiple regression analyses were performed to investigate the relationship and stewardship between different vitamin D forms and FGF-23 concentrations.', 'Chronic dialysis patients presented significantly higher FGF-23 concentrations. 25-OH-D concentrations of <20 ng/ml (deficiency), 20-30 ng/ml (insufficiency), and 30 ng/ml (sufficiency) were associated with progressively lower FGF-23 concentrations (p<0.01). Serum FGF-23 concentrations were significantly correlated with total (p=0.02), free (p<0.01) and bioavailable (p<0.01) 25-OH-D and total (p=0.04), free (p=0.02), and bioavailable (p=0.03) 1,25-(OH)2-D concentrations. With all 25-OH-D and 1,25-(OH)2-D forms in the regression model, we found that free 1,25-(OH)2-D outweighed all other vitamin D forms regarding its association with FGF-23 (p=0.03).\Question: Is serum free 1,25-dihydroxy-vitamin D more closely associated with fibroblast growth factor 23 than other vitamin D forms in chronic dialysis patients?
Output:
The relationship between FGF-23 and vitamin D is stronger using free forms of 25-OH-D and 1,25-(OH)2-D. Subsequent studies aiming at MBD should consider including free 25-OH-D and 1,25-(OH)2-D in the analysis.