The Chalder Fatigue Scale (CFQ 11)

The Fatigue Scale, sometimes referred to as the Chalder Fatigue Scale (the CFQ—to differentiate it from chronic fatigue syndrome or CFS), is a self-administered questionnaire for measuring the extent and severity of fatigue within both clinical and non-clinical, epidemiological populations. Although originally developed to measure the extent of chronic fatigue symptoms within clinical populations 1, the scale was revised and is now more widely used to measure the severity of ‘tiredness’ rather than just CFS 2. Tiredness and fatigue are important in both academic and applied occupational medicine—and the understanding of the link between them and employee health, performance, safety and general workability continues to grow. The need for a reliable self-completion tool that can measure this subjective condition, either in extreme clinical cases or in routine day-to-day functioning, has never been greater 3. As a short questionnaire, phrased in simple English with a straightforward answering system, it provides a brief tool to measure both physical and psychological fatigue. The items are benign and non-threatening, asking about sensations and functionality, rather than any beliefs or opinions about health status, such as ‘Do you have problems starting things?’ and ‘Do you have difficulty concentrating?’ Each of the 11 items are answered on a 4-point scale ranging from the asymptomatic to maximum symptomology, such as ‘Better than usual’, ‘No worse than usual’, ‘Worse than usual’ and ‘Much worse than usual’. For all items, the least symptomatic answers are on the left of the response-set, providing an easy-to-understand checklist for respondents. Using the Likert scoring method, responses on the extreme left receive a score of 0, increasing to 1, 2 or 3 as they become more symptomatic. The respondent’s global score can range from 0 to 33. The global score also spans two dimensions—physical fatigue (measured by items 1–7) and psychological fatigue (measured by items 8–11). The Likert scoring system allows for means and distributions to be calculated for both the global total as well as the two sub-scales. The CFQ 11 allows the user to differentiate between fatigue ‘cases’ and ‘non-cases’—responses in the two left-hand columns are scored with 0, while responses in the two right-hand columns receive 1. The sub-scales of physical and psychological fatigue are not used here, but rather the respondent receives a global binary fatigue score ranging from 0 to 11. The authors established that a global binary fatigue score of 3 or less represents scores of those who are not fatigued, with scores of 4 or more equating to ‘severe fatigue’. The scoring systems used in the CFQ 11 are virtually identical to the concepts of ‘caseness’ used in General Health Questionnaire and will be apparent to anyone familiar with that scale 4. Reliability coefficients for the CFQ 11 have been high in studies of CFS patients 5 as well as occupational and general population research, ranging from 0.90 for the Likert scoring method and 0.83 for the binary scoring method 3. The CFQ 11 has been used widely in studies ascertaining tiredness among working populations as well as patient groups and consistently fares extremely well against other longer and multidimensional tools 6. Another advantage is that the CFQ 11 is used widely in occupational research and allows for straightforward comparisons between studies and populations.