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Nephrology With Joel Topf, MD

Nephrology

Dr. Topf is an assistant clinical professor of medicine at Oakland University William Beaumont School of Medicine, creator and host of the Freely Filtered and Channel Your Enthusiasm podcasts, creator of the Precious Bodily Fluids blog, and co-creator of NephMadness and NephJC.

Newsflash: Vitamin D Still Does Not Slow Progression of CKD

Hello readers,

Short turnaround from newsletter to newsletter. This week we are shooting fish in a barrel. Vitamin D in CKD is in the crosshairs after The American Journal of Nephrology published a marketing puff piece disguised as a research manuscript. The study was a re-analysis of some studies from 2016 that purported to show that giving calcifediol slows the progression of CKD. What it really shows is that when you treat a bunch of CKD patients, some will progress slower than others, and the ones that progress slower are also more likely to have their PTH fall when given calcifediol.

In the original studies from 2016, as a secondary analysis, the investigators examined whether taking calcifediol affected eGFR. It didn’t. In any honest re-analysis, this nugget would have made it into the discussion. In fact, the whole point of the recent article could have been to point out that the response to calcifediol is a marker for a good renal prognosis, but because we have interventional RCT data, we know that it is not a result of calcifediol.

The 2024 KDIGO CKD guidelines are not kind to vitamin D, providing no guidance and just saying it is a thing that some people do. They also point out that the track record treating vitamin D is not good, with a reference to the 2012 EVOLVE trial.

Once again I summarize the whole affair in a blog post at PBFluids.

Thanks!

See you soon,

Joel Topf, MD

Articles
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    Use of Extended-Release Calcifediol to Treat Secondary Hyperparathyroidism in Stages 3 and 4 Chronic Kidney Disease - 6 day(s) ago

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      kidney_boy

      Here are the two original studies that were used to do this re-analysis. Both studies had the same study design and were packaged together in this manuscript. In these trials patients were randomized to study drug or matching placebo in a 2:1 ratio and maintaned on blinded drug for 6 months. After 6 months everyone was given study drug.

      The primary outcome was the percentage of patients who had a 30% reduction in PTH, and the drug worked with 33% of patients on calcifediol reaching that 30% reduction versus only 8% on placebo.

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    KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease - 6 day(s) ago

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      kidney_boy

      What do the 2024 KDIGO guidelines say about vitamin D in CKD? It's not great:

      despite evidence suggesting no benefit on clinical outcomes, (606) vitamin D replacement and calcimimetics to control PTH levels and to maintain calcium within the normal range are also common strategies.

      The footnote for 606 is a reference to Chertow's EVOLVE trial on cinacalcet in dialysis patients. 

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    Effect of Cinacalcet on Cardiovascular Disease in Patients Undergoing Dialysis - 6 day(s) ago

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      kidney_boy

      Here is Chertow's EVOLVE trial. This was the first study that I worked on as a site PI. I am proud that this study still stands as one of the most rigorous studies in CKD-MBD and though I am disappointed with the results, I believe that the findings were conclusive and continue to be instructive in showing that consistant and meaningful decreases in PTH do not prevent cardiovascular, or any* other, endpoints.

      *Yes, I know there was a reduction in parathyroidectomies, but those are often done for high PTH levels, so I am skeptical those represent true patient oriented outcomes.