Critical life events, infections, and symptoms during the year preceding chronic fatigue syndrome (CFS): An examination of CFS patients and subjects with a nonspecific life crisis

Objective: The purpose of this study was to describe the sequence of psycho social events and infections preceding the onset of chronic fatigue syndrom e (CFS). This information was related to the temporal development of crucia l symptoms in relation to the onset of, namely, fatigue, sadness, irritabil ity, pain, and feeling of fever. Methods: A personal interview was conducte d in 46 patients (mean age, 39.5 years; SD, 9 years) who fulfilled internat ional CFS criteria. These patients were matched with regard to age and gend er to 46 carefully matched control subjects. Twenty-three percent of the st udy subjects were men, and 77% were women. The patient at first identified the month that coincided with the onset of CFS. Similarly, each control sub ject was asked to identify a "very difficult period" within approximately t he same period as the patient with whom the control subject was matched. A list of 14 different life events was perused. Participants were asked to id entify for each month whether each of the listed events had occurred. Furth ermore, they were asked to rate the importance of the events they had exper ienced. In addition, for each of the cardinal symptoms (fatigue, sadness, i rritability, pain, and feeling of fever) and for each month, the subjects w ere asked to rate, on a visual analogue scale, the symptom intensity. Also, the number of infections was noted. Results: A statistically significant g roup difference in fatigue intensity existed during the period 4 to 10 mont hs before the onset of CFS. During the 3 months preceding the diagnosis for the CFS patients or the peak of the crisis for the control group, there wa s a dramatic rise in fatigue in both groups. The CFS group reached a much h igher fatigue level, which leveled off somewhat during the first year of fo llow-up but still remained very high in comparison with the control group, which reached precrisis levels 4 months after the peak. Similar patterns we re observed for fever and pain. With regard to sadness and irritability, no group difference was observed during the period preceding the crisis, in t he patient group, the level stayed high throughout the whole first year of follow-up, whereas a slow return started in the control group; precrisis le vels were reached after 1 year in this group. The prevalence ratio (CFS pat ients/control subjects) for negative events was around 1.0 for the periods 4 to 12 months preceding CFS but 1.9 during the quarter year preceding the onset. For infections, the prevalence ratio increased successively during t he four quarters preceding CFS (from 1.4 to 2.3). Conclusions: According to the retrospective self-reports, there were differences between the groups in fatigue, pain, and feeling of fever during the months preceding the cris is. With regard to depressive and irritable feelings, no preillness differe nces were reported between the groups. There was a reported excess prevalen ce of both infections and negative life events during the quarter year prec eding the onset of CFS or crisis. Potential sources of error are discussed. These findings must be replicated in longitudinal studies.