Background: Primary care studies of younger adults have reported fatigue to be common and etiologically heterogeneous with both physical and psychological associations. This has led to considerable debate about whether fatigue may present independently of psychological disorder. Somatic symptoms in older people have been assumed to be almost entirely physical in origin.
Aims: To determine the characteristics of fatigue and its relationship with psychological disorder in older primary care attenders.
Method: Ambulatory primary care patients aged 60 years and over completed self-report questionnaires and psychiatric interview at baseline and at 12 months.
Results: The overall prevalence of fatigue was 27.4% with most, but not all, cases being comorbid with psychological disorder. Psychological disorder (OR, 8.43; 95% CI, 2.98-23.88) was a greater predictor of fatigue than physical illness (OR, 4.74; 95% CI, 1.63-13.85). Neither a tendency for fatigue to evolve into psychological disorder, nor vice versa, was observed longitudinally (overall kappa, 0.68; P<.001).
Conclusions: Fatigue is common in older primary care attenders and is not associated with physical illness alone. Despite the high rate of comorbidity with psychological disorder, independent and longitudinally stable forms of fatigue did present. The overall findings suggest that while fatigue does overlap with psychological phenomena, there may also be distinct forms of fatigue.