title: Age and meteorological factors in the occurrence of spontaneous intracerebral hemorrhage in a metropolitan city.
abstract: OBJECTIVE
  The aim of this study was to investigate the correlation between meteorological factors and occurrence of spontaneous intracerebral hemorrhage (ICH) according to age.
  
  
  METHODS
  We retrospectively analyzed the records of 735 ICH patients in a metropolitan hospital-based population. Observed and expected numbers of ICH patients were obtained at 5℃ intervals of ambient temperature and a ratio of observed to expected frequency was then calculated. Changes in ambient temperature from the day before ICH onset day were observed. The Wilcoxon-Mann-Whitney test was used to test differences in meteorological variables between the onset and non-onset days. The Kruskal-Wallis test was used for comparison of meteorological variables across gender and age.
  
  
  RESULTS
  ICH was observed more frequently (observed/expected ratio ≥ 1) at lower mean, minimum, and maximum ambient temperature (p = 0.0002, 0.0003, and 0.0002, respectively). Significantly lower mean, minimum, and maximum ambient temperature, dew point temperature, wind speed, and atmospheric pressure (p = 0.0003, 0.0005, 0.0001, 0.0013, 0.0431, and 0.0453, respectively) was observed for days on which spontaneous ICH occurred. In the subgroup analysis, the ICH onset day showed significantly lower mean, minimum, and maximum ambient temperature, dew point temperature, relative humidity, and higher atmospheric pressure in the older (≥ 65 years) female group (p = 0.0093, 0.0077, 0.0165, 0.0028, 0.0055, and 0.0205, respectively).
  
  
  CONCLUSIONS
  Occurrence of spontaneous ICH is closely associated with meteorological factors and older females are more susceptible to lower ambient temperature.
authors.affiliation: Department of Neurosurgery, Eulji Hopsital, Eulji University, Seoul, Korea.
authors.forename: Hyung Jun
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Eulji Hopsital, Eulji University, Seoul, Korea.
authors.forename: Jae Hoon
authors.identifier: 0000-0002-9179-8569
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Eulji Hopsital, Eulji University, Seoul, Korea.
authors.forename: Duk Ryung
authors.initials: DR
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Eulji Hopsital, Eulji University, Seoul, Korea.
authors.forename: Hee In
authors.initials: HI
authors.lastname: Kang
authors.affiliation: Department of Neurosurgery, Eulji Hopsital, Eulji University, Seoul, Korea.
authors.forename: Byung Gwan
authors.initials: BG
authors.lastname: Moon
authors.affiliation: Department of Neurosurgery, Eulji Hopsital, Eulji University, Seoul, Korea.
authors.forename: Joo Seung
authors.initials: JS
authors.lastname: Kim
keywords: Age; Meteorology; Spontaneous intracerebral hemorrhage