title: Risk and predictors of fatigue after infectious mononucleosis in a large primary-care cohort.
abstract: BACKGROUND
  Fatigue has been found to complicate infectious mononucleosis (IM) when patients are directly asked about it. We do not know whether such fatigue is clinically significant, nor whether IM is a specific risk for fatigue (or whether it can follow other common infections). Various risk markers for post-infectious fatigue have been identified, but findings are inconsistent.
  
  
  OBJECTIVE
  To determine the risk of clinically reported fatigue (compared with depression) after IM (compared with both influenza and tonsillitis) in patients attending primary care, and to examine risk markers for post-IM fatigue.
  
  
  METHODS
  Comparison of matched primary-care cohorts.
  
  
  METHODS
  We identified 1438 adult patients with a positive heterophil antibody test for IM from the UK General Practice Research Database. These patients were individually matched on age, sex and practice to two comparison groups; one with a clinical diagnosis of influenza and the other of tonsillitis.
  
  
  RESULTS
  The odds ratios (ORs) (95%CI) for reported fatigue after IM vs. influenza and tonsillitis were 4.4 (2.9-6.9) and 6.6 (4.2-10.4), respectively. Risk markers for post-IM fatigue included female sex and premorbid mood disorder. By comparison, the ORs for depression after IM vs. influenza and tonsillitis were 1.6 (0.9-2.6) and 2.3 (1.4-3.9), respectively.
  
  
  CONCLUSIONS
  IM is a specific and significant risk for clinically reported fatigue, which is both separate from, and more common than, depression. Female sex and premorbid mood disorder are risk markers for fatigue. These can be used both to target prevention strategies and to explore aetiological mechanisms.
authors.affiliation: Centre for Psychiatry, Barts and The London, Queen Mary's School of Medicine and Dentistry, UK.
authors.forename: I
authors.initials: I
authors.lastname: Petersen
authors.forename: J M
authors.initials: JM
authors.lastname: Thomas
authors.forename: W T
authors.initials: WT
authors.lastname: Hamilton
authors.forename: P D
authors.initials: PD
authors.lastname: White
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003866:Depressive Disorder / Q000453:epidemiology / Q000821:virology; D005221:Fatigue / Q000453:epidemiology / Q000821:virology*; D015673:Fatigue Syndrome, Chronic / Q000453:epidemiology / Q000821:virology; D005260:Female; D006801:Humans; D007244:Infectious Mononucleosis / Q000150:complications* / Q000453:epidemiology; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D014069:Tonsillitis / Q000150:complications / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology