The study – published in JAMA – investigated the effects of daily consumption of the vitamin D2 analogue compound paricalcitol on heart functioning in patients with chronic kidney disease in a double-blind, randomised placebo-controlled trial that was initiated by the investigators, and sponsored by industry (Abbott Laboratories).
Led by researchers from Massachusetts General Hospital, USA, the study reported that patients with chronic kidney disease who received the sunshine vitamin compound for up 48 weeks did not show improvement on measures of cardiac structure, function, or left ventricular mass – compared to patients who received placebo.
"Several studies have suggested that vitamin D therapy may improve cardiovascular health, so we were surprised that the results did not support our hypothesis that paricalcitol, which we use to treat hyperparathyroidsm in kidney disease patients, would reduce left ventricular hypertrophy and improve diastolic function in these patients," said Dr Ravi Thadhani, of Massachusetts General Hospital and lead author of the trial.
"There was some evidence that paricalcitol may reduce the incidence of heart failure, but that will need to be followed up in a larger trial focused on that potential outcome," he added.
Thadhani and his colleagues explained that the PRIMO (Paricalcitol capsule benefits in Renal-failure-Induced MOrbidity) study enrolled 227 participants from 60 centres in 11 countries – all of whom had chronic kidney disease and mild to moderate enlargement of the of the heart's main pumping chamber (left ventricle).
The research team found that almost a year's treatment with the vitamin D compound did nothing to alleviate key structural and functional cardiovascular abnormalities in patients with kidney disease and heart enlargement, with the international team reporting that daily doses of the vitamin D2 analogue did not reduce enlargement or improve impaired functioning of the left ventricle.
Pre-specified measures of the hearts diastolic functions also did not significantly differ between the vitamin D and placebo groups, reported the authors. They added that the number of hospitalisations from ‘any cause’ and from ‘non-cardiovascular causes’ did not differ between groups, however, there were fewer hospitalisations for cardiovascular events in the vitamin D group when compared to the placebo group.
Writing in an accompanying editorial (doi: 10.1001/jama.2012.159), Dr Stefan Anker and Dr Stephan von Haehling of Charite Campus Virchow-Klinikum, Germany, argued that the deciding factor for whether to offer vitamin D supplementation to people with chronic kidney disease (CKD) “should be based on improvement in important clinical outcomes rather than other end points.”
"At this time, paricalcitol cannot be recommended for patients with CKD,” said Anker and von Haehling, who argued that the current trial should to be followed by a larger trial that is adequately powered to assess end points including heart-related hospitalisations, dialysis events, and mortality.
“Considering the competition for public funding of clinical trials in CKD, the pro-vitamin D research groups may face an uphill battle to keep this ... viable for patients with CKD," they said.
Published online ahead of print, doi: 10.1001/jama.2012.120
“Vitamin D Therapy and Cardiac Structure and Function in Patients With Chronic Kidney Disease”
Authors: R. Thadhani, E. Appelbaum, Y. Pritchett, Y. Chang, J. Wenger, H. Tamez et al