title: The relative importance of specific risk factors for insomnia in women treated for early-stage breast cancer.
abstract: BACKGROUND
  Many individual risk factors for insomnia have been identified for women with a history of breast cancer. We assessed the relative importance of a wide range of risk factors for insomnia in this population.
  
  
  METHODS
  Two thousand six hundred and forty-five women < or =4 years post-treatment for Stage I (> or =1 cm)-IIIA breast cancer provided data on cancer-related variables, personal characteristics, health behaviors, physical health/symptoms, psychosocial variables, and the Women's Health Initiative-Insomnia Rating Scale (WHI-IRS; scores > or =9 indicate clinically significant insomnia).
  
  
  RESULTS
  Thirty-nine per cent had elevated WHI-IRS scores. In binary logistic regression, the variance in high/low insomnia group status accounted for by each risk factor category was: cancer-specific variables, 0.4% (n.s.); personal characteristics, 0.9% (n.s.); health behaviors, 0.6% (n.s.); physical health/symptoms, 13.4% (p<0.001); and, psychosocial factors, 11.4% (p<0.001). Insomnia was associated with worse depressive (OR = 1.32) and vasomotor symptoms (particularly night sweats) (OR = 1.57).
  
  
  CONCLUSIONS
  Various cancer-specific, demographic, health behavior, physical health, and psychosocial factors have been previously reported as risk factors for insomnia in breast cancer. In our study (which was powered for simultaneous examination of a variety of variables), cancer-specific, health behavior, and other patient variables were not significant risk factors when in the presence of physical health and psychosocial variables. Only worse depressive and vasomotor symptoms were meaningful predictors.
authors.affiliation: Rebecca & John Moores Cancer Center, University of California, San Diego, CA 92093, USA. wabardwell@ucsd.edu
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Bardwell
authors.forename: Judith
authors.initials: J
authors.lastname: Profant
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Casden
authors.forename: Joel E
authors.initials: JE
authors.lastname: Dimsdale
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
authors.forename: Loki
authors.initials: L
authors.lastname: Natarajan
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Rock
authors.forename: John P
authors.initials: JP
authors.lastname: Pierce
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000628:therapy*; D005260:Female; D006304:Health Status; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D011584:Psychology; D012307:Risk Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D016387:Women's Health