[Influence of vascular risk factors on seasonality of benign paroxysmal positional vertigo]

Objective: To investigate the seasonal changes of benign paroxysmal positional vertigo (BPPV) onset, and explore the relationship between vascular risk factors and the seasonal patterns of BPPV. Methods: Data of 3 886 patients subjected to vestibular function examination and diagnosed with BPPV who underwent manipulation or instrumental repositioning from January 1, 2016 to December 31, 2019 in the Department of Neurology, Beijing Tiantan Hospital were retrospectively analyzed. Demographic information and medical history of the patients were recorded. Weather temperature data of Beijing were obtained and monthly averages were calculated. The relationship between the BPPV onset and temperature and seasonality was investigated. Meanwhile, the influence of vascular risk factors on the seasonal patterns of BPPV was determined. Results: BPPV is more common in women (n=2 667). The male to female ratio of patients was approximately 1∶2, with a mean age of (55±13) years. The cases of BPPV in spring (March-May), summer (June-August), autumn (September-November) and winter (December-February) were 1 000 (25.7%), 911 (23.4%), 808 (20.8%) and 1 167 (30.0%), respectively. The peak incidence of BPPV occurred in December (n=491) and the lowest occurred in September (n=251). The number of BPPV cases diagnosed monthly was inversely correlated with mean temperature (R²=0.317; P<0.001). Patients with ≥2 vascular risk factors were at higher risk of developing BPPV in spring or winter than those without risk factors (OR=1.32, 95%CI: 1.13-1.53,P<0.001). Proportion of onset in spring or winter increased with each additional risk factor (P trend<0.001). Conclusions: BPPV often occurs in the months with low temperature (spring and winter) and the number of cases is inversely correlated with temperature. Compared with those with no vascular risk factors, patients with more vascular risk factors are more likely to develop BPPV in spring and winter.