title: Association between shelter crowding and incidence of sleep disturbance among disaster evacuees: a retrospective medical chart review study.
abstract: OBJECTIVE
  We determined whether crowding at emergency shelters is associated with a higher incidence of sleep disturbance among disaster evacuees and identified the minimum required personal space at shelters.
  
  
  METHODS
  Retrospective review of medical charts.
  
  
  METHODS
  30 shelter-based medical clinics in Ishinomaki, Japan, during the 46 days following the Great Eastern Japan Earthquake and Tsunami in 2011.
  
  
  METHODS
  Shelter residents who visited eligible clinics.
  
  
  METHODS
  Based on the result of a locally weighted scatter-plot smoothing technique assessing the relationship between the mean space per evacuee and cumulative incidence of sleep disturbance at the shelter, eligible shelters were classified into crowded and non-crowded shelters. The cumulative incidence per 1000 evacuees was compared between groups, using a Mann-Whitney U test. To assess the association between shelter crowding and the daily incidence of sleep disturbance per 1000 evacuees, quasi-least squares method adjusting for potential confounders was used.
  
  
  RESULTS
  The 30 shelters were categorised as crowded (mean space per evacuee <5.0 m(2), 9 shelters) or non-crowded (≥ 5.0 m(2), 21 shelters). The study included 9031 patients. Among the eligible patients, 1079 patients (11.9%) were diagnosed with sleep disturbance. Mean space per evacuee during the study period was 3.3 m(2) (SD, 0.8 m(2)) at crowded shelters and 8.6 m(2) (SD, 4.3 m(2)) at non-crowded shelters. The median cumulative incidence of sleep disturbance did not differ between the crowded shelters (2.3/1000 person-days (IQR, 1.6-5.4)) and non-crowded shelters (1.9/1000 person-days (IQR, 1.0-2.8); p=0.20). In contrast, after adjusting for potential confounders, crowded shelters had an increased daily incidence of sleep disturbance (2.6 per 1000 person-days; 95% CI 0.2 to 5.0/1000 person-days, p=0.03) compared to that at non-crowded shelters.
  
  
  CONCLUSIONS
  Crowding at shelters may exacerbate sleep disruptions in disaster evacuees; therefore, appropriate evacuation space requirements should be considered.
authors.affiliation: Department of Emergency Medicine, University of Fukui Hospital, Fukui Prefecture, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Kawano
authors.affiliation: Department of Primary Care and Emergency Medicine, Kyoto University Graduate School of Medicine, Kyoto Prefecture, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Nishiyama
authors.affiliation: Department of Emergency Medicine, University of Fukui Hospital, Fukui Prefecture, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Morita
authors.affiliation: Department of Community Health Care Promotion, University of Fukui Hospital, Fukui Prefecture, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamamura
authors.affiliation: Department of Acute Medicine, Faculty of Medicine, Kinki University, Osaka Prefecture, Japan.
authors.forename: Atsuchi
authors.initials: A
authors.lastname: Hiraide
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Kohei
authors.initials: K
authors.lastname: Hasegawa
mesh_terms: D000328:Adult; D000368:Aged; D003441:Crowding / Q000523:psychology*; D055866:Earthquakes; D060447:Emergency Shelter; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012893:Sleep Wake Disorders / Q000453:epidemiology / Q000209:etiology*; D057192:Tsunamis
keywords: ACCIDENT & EMERGENCY MEDICINE; MENTAL HEALTH; PUBLIC HEALTH; SLEEP MEDICINE