The temporal stability and co-morbidity of prolonged fatigue: a longitudinal study in primary care

Psychol Med. 1999 Jul;29(4):855-61. doi: 10.1017/s0033291799008582.


Background: Depression, anxiety and fatigue are among the most common symptoms presented in primary care. Whether such symptoms indicate discrete psychological syndromes or whether they result from a common vulnerability is not clear. This study examined longitudinally the patterns of co-morbidity between prolonged fatigue and other forms of psychological distress in patients attending general practitioners.

Methods: Adults attending primary care completed questionnaires designed to detect cases of prolonged fatigue and psychological distress at presentation and 12 months later.

Results: Of 652 patients, the prevalence rates of 'prolonged fatigue' alone, 'psychological distress' alone, 'prolonged fatigue + psychological distress' and 'no disorder' were 7%, 19%, 15% and 59% respectively at initial assessment. Of those patients with any prolonged fatigue syndrome initially, 58% still reported fatigue 12 months later (representing 13% of the total sample). Most importantly, the risk of developing prolonged fatigue was not increased in patients who initially had psychological distress (OR = 0.95; 95% CI 0.2-3.6), neither was the risk of developing psychological distress increased in patients who initially had prolonged fatigue (OR = 1.4; 95% CI 0.6-3.4).

Conclusions: This study indicates that prolonged fatigue is a persistent diagnosis over time. The longitudinal patterns of co-morbidity with psychological distress do not support an aetiological model that proposes a common vulnerability factor for these disorders. Psychiatric classification systems may be better served by treating prolonged fatigue and psychological distress as independent disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anxiety Disorders / diagnosis
  • Anxiety Disorders / epidemiology*
  • Anxiety Disorders / psychology
  • Comorbidity
  • Depressive Disorder / diagnosis
  • Depressive Disorder / epidemiology*
  • Depressive Disorder / psychology
  • Fatigue Syndrome, Chronic / diagnosis
  • Fatigue Syndrome, Chronic / epidemiology*
  • Fatigue Syndrome, Chronic / psychology
  • Female
  • Humans
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Neurasthenia / diagnosis
  • Neurasthenia / epidemiology*
  • Neurasthenia / psychology
  • New South Wales
  • Primary Health Care
  • Risk Factors