Association between serum 25-hydroxyvitamin D levels and prognosis in benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is a common peripheral vestibular disorder in which early nonresponse and recurrence remain clinically important. Vitamin D has been hypothesized to influence otoconial stability and inner-ear mineral homeostasis and may be associated with BPPV prognosis. This study aimed to evaluate the association between baseline serum 25-hydroxyvitamin D [25(OH)D] levels and prognosis in BPPV.

This retrospective cohort consecutively included 286 patients with BPPV diagnosed between January 2021 and December 2025. Baseline serum 25(OH)D was measured at initial presentation and categorized as deficiency (<20 ng/mL), insufficiency (20 to 29 ng/mL), or sufficiency (≥30 ng/mL). The primary outcome was 1-week short-term response, defined as complete symptom resolution plus conversion to a negative positional test after canalith repositioning. Secondary outcomes included repositioning maneuver burden, Dizziness Handicap Inventory (DHI) scores and change, and recurrence during follow-up. Multivariable logistic and linear regression models were used with stepwise adjustment.

The overall 1-week response rate was 50.7%, with group-specific rates of 35.4% in the deficient group, 48.6% in the insufficient group, and 68.9% in the sufficient group (χ ² = 12.84, p = 0.002). Higher baseline serum 25(OH)D was independently associated with a greater likelihood of 1-week response (adjusted odds ratio per 5 ng/mL increase, 1.49; 95% confidence interval [CI], 1.20 to 1.85; p < 0.001). Among responders, vitamin D sufficiency was associated with lower odds of requiring multiple repositioning sessions than deficiency (adjusted odds ratio, 0.12; 95% CI, 0.03 to 0.48; p = 0.003). Baseline and week-1 DHI differed across 25(OH)D categories, whereas change in DHI did not remain independently associated with 25(OH)D (β = 0.12; 95% CI, -0.17 to 0.41; p = 0.405). During follow-up of at least 3 months, recurrence occurred in 21.3% of patients, with rates of 33.3, 21.5, and 11.5% in the deficient, insufficient, and sufficient groups, respectively (χ ² = 7.65, p = 0.022).

Higher baseline serum 25(OH)D levels were associated with better short-term therapeutic response, lower repositioning burden, and lower recurrence proportion in BPPV. These findings suggest that baseline serum 25(OH)D may be relevant to prognostic stratification, but prospective studies are needed to clarify causality and clinical utility.