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Published on: October 15, 2021
Snowfall reduces the risk of chronic subdural hematoma onset: Analysis of an administrative database in Japan
Kazunori Oda1, Shotaro Aso2, Yujiro Hattori1,3
1Department of Neurological Surgery, Nippon Medical School, Bunkyo-ku, Japan.
Insights
First snowfall events in Japan did not significantly impact the onset of chronic subdural hematoma (CSDH). While some initial findings suggested a reduction, further analysis confirmed no overall effect on CSDH incidence.
Area of Science:
- Neurosurgery
- Environmental Medicine
- Epidemiology
Background:
- Chronic subdural hematoma (CSDH) is a common neurosurgical condition.
- Previous observations suggested a link between first snowfall and CSDH onset, but evidence was limited.
- This study investigates the association between CSDH incidence and first snowfall events in Japan.
Purpose of the Study:
- To examine the relationship between the onset of chronic subdural hematoma (CSDH) and first snowfall events.
- To determine if meteorological factors, specifically first snowfall, influence CSDH occurrence.
Main Methods:
- Retrospective analysis of the Japanese Diagnosis Procedure Combination inpatient database (2010-2016).
- Correlation with snowfall data from the Japan Meteorological Agency.
- Statistical evaluation using binomial approximation and odds ratios to compare CSDH incidence before and after first snowfall.
Main Results:
- A total of 8526 CSDH patients were analyzed.
- While 65.4% of cases occurred before first snowfall, 34.6% occurred after.
- First snowfall was initially associated with reduced CSDH occurrence (OR 0.53), but subgroup analysis showed no effect for October snowfall.
Conclusions:
- First snowfall events do not significantly affect the onset of chronic subdural hematoma (CSDH) in Japan.
- The observed association was not consistent across all months, particularly October.
- This finding challenges previous hypotheses regarding snowfall and CSDH incidence.
Background:
Chronic subdural hematoma (CSDH) is a frequently observed disease in neurosurgical practice. Although first snowfall has been considered to increase the onset of CSDH, few reports have assessed the relationship between snowfall and CSDH. In this study, we aimed to investigate the relationship between CSDH onset and first snowfall events.
Methods:
This retrospective study was based on the Japanese Diagnosis Procedure Combination inpatient database from July 1, 2010, to March 31, 2016, and on the global observation of snowfall events in Japan obtained from the Japan Meteorological Agency. We used a binomial approximation to evaluate the average number of CSDH patients after first snowfall events compared with that before first snowfall events. We calculated the odds ratio of CSDH onset on the first snowfall.
Results:
We identified 8526 CSDH patients from the database. A total of 5573 (65.4%) were observed before first snowfall events, and 2953 (34.6%) after first snowfall events. The first snowfall of winter was significantly associated with a reduction in the occurrence of CSDH (odds ratio, 0.53; 95% confidence interval; 0.51-0.55). In subgroup analysis, only the first snowfall in October was not associated with reduction in the occurrence of CSDH.
Conclusion:
First snowfall events did not affect the onset of CSDH in Japan.
