This post was amended based on the comment from the NNT team below.
Written by Clay Smith
Supplementation with vitamin D and calcium, in addition to standard canalith repositioning maneuvers, reduced the number of episodes of benign paroxysmal peripheral vertigo (BPPV) per year in adult patients.
Why does this matter?
Otoconia are calcium crystals that make the otolithic membrane heavier than the surrounding fluid. Calcium is required for otoconia crystallization. Low calcium may lead to greater otoconia turnover and release of crystalline debris, which might precipitate an attack of BPPV. Anecdotally, some patients have improved with vitamin D and calcium supplementation. Would this prove true in a RCT?
Epley + calcium = relief? Looks like it may…
This was a multicenter randomized trial that enrolled 1050 patients with BPPV who all had canalith repositioning maneuvers. About half received vitamin D and calcium supplementation, and half did not. Specifically, the treatment group got vitamin D 400 IU and 500 mg of calcium carbonate twice a day for one year if their serum vitamin D level was lower than 20 ng/ml. There was no placebo, and the non-treatment patients were not to take vitamin D or calcium supplements. For the primary outcome, the annual recurrence rate per person-year using intention to treat was 0.83 in the treatment arm vs. 1.10 in the non-treatment group. Two patients in the treatment arm developed hypercalcemia and had to stop medication.
The trial was retrospectively registered on ClinicalTrials.gov due to translation delays from Korean to English. That’s not ideal. They also changed the primary outcome from proportion of patients with recurrence to the absolute number of recurrences per patient (annual recurrence rate of BPPV per one-person year). Turns out, the overall proportion of patients with recurrence was also lower with treatment: 37.8 vs. 46.7%, p=0.005 (NNT = 11). There was large loss to follow up, with only 80% of the intervention group making it a year and 92% of the non-treatment group. Despite these challenges, on intention to treat, per protocol, and Kaplan-Meier time to event curve analysis, all showed benefit with treatment. I think this treatment effect is probably real. But I wonder if expecting to test vitamin D levels, treat with vitamin D and calcium, and recheck calcium and vitamin D levels for a year is realistic? Something more pragmatic might be a better approach in future studies.
Prevention of Benign Paroxysmal Positional Vertigo with Vit D Supplementation: A Randomized Trial. Neurology. 2020 Aug 5:10.1212/WNL.0000000000010343. doi: 10.1212/WNL.0000000000010343. Online ahead of print.
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