title: Weekly and holiday-related patterns of panic attacks in panic disorder: a population-based study.
abstract: BACKGROUND
  While chronobiological studies have reported seasonal variation in panic attacks (PA) episodes, information on the timing of PA by week-days may enable better understanding of the triggers of PA episodes and thereby provide pointers for suitable interventional approaches to minimize PA attacks. This study investigated weekly variation in potential PA admissions including associations with holidays using a population-based longitudinal, administrative claims-based dataset in an Asian population.
  
  
  METHODS
  This study used ambulatory care data from the "Longitudinal Health Insurance Database 2000. We identified 993 patients with panic disorder (PD), and they had 4228 emergency room (ER) admissions for potential PA in a 3-year period between 1 January 2009 and 31 December 2011. One-way analysis of variance (ANOVA) was used to examine associations between the potential PA admissions and holidays/weekend days/work-days of the week.
  
  
  RESULTS
  The daily mean number of potential PA admissions was 3.96 (standard deviation 2.05). One-way ANOVA showed significant differences in potential PA admissions by holiday and day of the week (p<0.001). Daily frequencies showed a trough on Wednesday-Thursday, followed by a sharp increase on Saturday and a peak on Sunday. Potential PA admissions were higher than the daily mean for the sample patients by 29.4% and 22.1%, respectively on Sundays and holidays. Furthermore, the weekly variations were similar for females and males, although females always had higher potential PA admissions on both weekdays and holidays than the males.
  
  
  CONCLUSIONS
  We found that potential PA admissions among persons with PD varied systematically by day of the week, with a significant peak on weekends and holidays.
authors.affiliation: Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan; Sleep Research Center, Taipei Medical University Hospital, Taipei, Taiwan.
authors.forename: Li-Ting
authors.initials: LT
authors.lastname: Kao
authors.affiliation: Arnold School of Public Health, Department of Health Services Policy and Management, University of South Carolina, Columbia, South Carolina, United States of America.
authors.forename: Sudha
authors.initials: S
authors.lastname: Xirasagar
authors.affiliation: Taipei Medical University Hospital, Department of Psychiatry, Taipei, Taiwan; Taipei Medical University, School of Medicine, Department of Psychiatry, Taipei, Taiwan.
authors.forename: Kuo-Hsuan
authors.initials: KH
authors.lastname: Chung
authors.affiliation: Sleep Research Center, Taipei Medical University Hospital, Taipei, Taiwan; Taipei Medical University, School of Health Care Administration, Taipei, Taiwan.
authors.forename: Herng-Ching
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Department of Urology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan.
authors.forename: Shih-Ping
authors.initials: SP
authors.lastname: Liu
authors.affiliation: Sleep Research Center, Taipei Medical University Hospital, Taipei, Taiwan; Division of Urology, Department of Surgery, Far Eastern Memorial Hospital, Ban Ciao, Taipei, Taiwan; School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Shiu-Dong
authors.initials: SD
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006693:Holidays; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D016584:Panic Disorder / Q000453:epidemiology* / Q000628:therapy; D013315:Stress, Psychological / Q000453:epidemiology / Q000628:therapy; D055815:Young Adult