title: Patient overcrowding in hospital wards as a predictor of diagnosis-specific mental disorders among staff: a 2-year prospective cohort study.
abstract: OBJECTIVE
  Hospital ward patient overcrowding has been hypothesized to increase psychiatric morbidity among staff, but it is unknown whether the association is specific to depressive disorders. This study examined whether patient overcrowding in hospital wards predicts diagnosis-specific mental disorders among staff.
  
  
  METHODS
  A 2-year prospective cohort study was conducted, in which the extent of hospital ward overcrowding was determined using routinely recorded patient bed occupancy rates between 2003 and 2004 and linked to sickness absence for 5,166 nurses and physicians in 203 somatic illness wards in 16 Finnish acute-care hospitals. Medically certified long-term (> 9 days) sickness absence spells in 2004 and 2005 with physician-determined diagnosis (based on ICD-10 criteria) were obtained from the register of the Social Insurance Institution of Finland.
  
  
  RESULTS
  Cox proportional hazard models for recurrent events adjusted for sex, age, occupation, type and length of employment contract, hospital district, and specialty showed that health professionals working in wards with a patient occupancy level 10 percentage units above the optimal during a 1-year period experienced twice the risk of sickness absence due to depressive disorders (HR = 1.95; 95% CI, 1.18-3.24) relative to colleagues working in wards with optimal or below-occupancy levels. No significant association was found for diagnoses of severe stress and adjustment disorders or other psychiatric disorders.
  
  
  CONCLUSIONS
  Chronic workload, as expressed by patient overcrowding in hospital wards, is associated with the onset of depressive disorders among staff.
authors.affiliation: Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, 00250 Helsinki, Finland. marianna.virtanen@ttl.fi
authors.forename: Marianna
authors.initials: M
authors.lastname: Virtanen
authors.forename: G David
authors.initials: GD
authors.lastname: Batty
authors.forename: Jaana
authors.initials: J
authors.lastname: Pentti
authors.forename: Jussi
authors.initials: J
authors.lastname: Vahtera
authors.forename: Tuula
authors.initials: T
authors.lastname: Oksanen
authors.forename: Katinka
authors.initials: K
authors.lastname: Tuisku
authors.forename: Paula
authors.initials: P
authors.lastname: Salo
authors.forename: Kirsi
authors.initials: K
authors.lastname: Terho
authors.forename: Kirsi
authors.initials: K
authors.lastname: Ahola
authors.forename: Marko
authors.initials: M
authors.lastname: Elovainio
authors.forename: Mika
authors.initials: M
authors.lastname: Kivimäki
mesh_terms: D000328:Adult; D003441:Crowding / Q000523:psychology*; D005260:Female; D006757:Hospital Units / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis*; D010361:Patients; D010564:Personnel, Hospital / Q000523:psychology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D016526:Workload / Q000523:psychology