Similarities, overlap and differences between burnout and prolonged fatigue in the working population
From the 1Department of Epidemiology, 2Department of Medical, Clinical, and Experimental Psychology, and 3Department of General Practice, Maastricht University, Maastricht, The Netherlands
Address correspondence to Drs S. Leone, Department of Epidemiology, Research Institute Caphri, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. email: stephanie.leone{at}epid.unimaas.nl
Received 13 March 2007 and in revised form 24 May 2007
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Background: Burnout and prolonged fatigue are related but distinct concepts that have seldom been empirically compared.
Aim: To examine similarities, overlap and differences between burnout and prolonged fatigue.
Design: Observational study.
Methods: We analysed baseline data from the Maastricht Cohort Study on Fatigue at Work (n = 12 140). The discriminative abilities of the Checklist Individual Strength (CIS) and the Maslach Burnout Inventory–General Survey (MBI-GS) were evaluated using principal component analysis. Overlap, similarities and differences regarding health, work and demographic factors between subgroups were assessed.
Results: The discriminative abilities of the CIS and MBI-GS appeared to be moderate. Prolonged fatigue and burnout cases overlapped considerably. The subgroup consisting of cases with concurrent fatigue and burnout tended to have poorer outcomes in terms of health and work factors than the subgroups with either prolonged fatigue or burnout. Similar patterns were found for subjective fatigue and exhaustion.
Discussion: There appear to be some relevant differences between burnout and prolonged fatigue, with respect to work and health factors. Burnout and prolonged fatigue can occur both separately and simultaneously. Having both conditions simultaneously seems to be associated with worse outcomes than having either alone.
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Introduction |
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Burnout and prolonged fatigue are two conditions in which the symptom of fatigue plays a central role.1 These two conditions come from different backgrounds: typically prolonged fatigue comes from a medical background2,3 while burnout comes from a psychological background.1 Furthermore, they are also conceptualized differently: burnout is conceptualized as a work related condition and prolonged fatigue as a general condition.4 Despite these differences, it is likely that they share similarities in terms of complaints, course and consequences. Moreover, the distinction that is made between burnout and fatigue conditions could have consequences in terms of prognosis, treatment and work reintegration due to the assigned label, when they may be more similar than different. The concepts of burnout and prolonged fatigue have, however, hardly been compared in empirical research, so little is known about the differences or similarities between them.
Fatigue is a complex phenomenon. Besides occurring as a symptom alongside another primary medical or psychiatric condition, it can also be the main clinical complaint or condition.5 However, in the majority of cases in which fatigue is the central complaint, no medical explanation can be found 5,6 and therefore, the cause of fatigue remains medically unexplained. Moreover, whereas acute fatigue disappears after a period of rest, prolonged fatigue is not easily reversible in the short term.7 Although the medical reason is unknown, prolonged fatigue can occur both within and outside the context of work. The complexity of fatigue is also evident from the many different definitions used to describe fatigue and the various accompanying measures of fatigue.3,8 One such measure is the Checklist Individual Strength (CIS), which is a multidimensional measure of prolonged fatigue, and includes items on subjective fatigue, motivation, activity and concentration. It was originally developed to measure prolonged unexplained fatigue (lasting at least 2 weeks) in chronic fatigue syndrome patients, but has been validated in the working population.9–11 Studies in the working population have shown that prolonged fatigue can predict sickness absence and work disability.12,13
Burnout is a condition related to both fatigue and work. It was originally conceptualized as a syndrome consisting of emotional exhaustion, depersonalization and reduced personal accomplishment, among individuals in 'helping' professions.14 The most widely used measure to examine the three dimensions of burnout is the Maslach Burnout Inventory (MBI).1 As the original MBI could not be applied in occupations outside the human services, a more general version of the MBI was developed: the MBI General Survey (MBI-GS).15 The MBI-GS measures three dimensions of burnout in generic (as opposed to occupation-specific) terms.16 Unlike prolonged fatigue, burnout is assumed to occur only inside the context of work, although this is an ongoing point of debate in the burnout literature.4 Like prolonged fatigue, burnout can also predict sickness absence.17,18
Although the MBI-GS and the CIS are quite different, they have in common that they are both multidimensional measures with core complaints, exhaustion and subjective fatigue respectively, and that the core complaint of both measures is very similar. In studies examining the exhaustion component of burnout along with several other measures of fatigue, exhaustion appeared to measure the same concept.8,19,20 Moreover, De Vries et al.8 and Michielsen et al.19 found correlations between exhaustion and subjective fatigue of 0.65 and 0.60, respectively. However, it has been argued that burnout should not be reduced to merely exhaustion, even though exhaustion is the central component of burnout.4,16 Various studies have shown that causal attributions have an effect on the course of chronic fatigue and chronic fatigue syndrome.21–24 In particular, those who attribute their fatigue complaints to a somatic cause rather than a psychological cause have a poorer prognosis. It is possible that the psychological background of burnout could influence these attributions. In one study comparing unexplained fatigue, chronic fatigue syndrome and burnout, it was found that although the conditions shared some important characteristics, a distinguishing feature between fatigue and burnout seemed to be the causal attributions made by patients.25
We aimed to gain more insight into similarities, overlap and differences between burnout and prolonged fatigue as conceptualized by the MBI-GS and CIS, respectively, by addressing two issues. Firstly, we assessed the ability of the instruments that were developed to measure burnout (MBI-GS) and prolonged fatigue (CIS) to discriminate between these conditions. This is a prerequisite to comparing burnout and prolonged fatigue. Secondly, we examined the overlap and the similarities and differences in terms of health, work and demographic factors between burnout and prolonged fatigue cases. This comparison allows some insight into whether a relevant distinction can be made between burnout and prolonged fatigue or if they are in fact more similar than different.
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Design
Baseline data from the Maastricht Cohort Study on Fatigue at Work (MCS) were used for this study, including employees from 45 different companies and organizations. The baseline data were gathered in May 1998 by means of a self-administered questionnaire. A total of 12 140 employees participated at baseline (response rate 45%). There were statistically significant differences at baseline between non-respondents and respondents: non-respondents reported fewer fatigue complaints, less sickness absence and less difficulty in work execution, compared to respondents. Detailed information on the design of the MCS is provided elsewhere.26
Study population
Participants at baseline of the MCS were included in this study. Subgroups based on prolonged fatigue cases and burnout cases, and on exhaustion cases and subjective fatigue cases, were examined. Participants were excluded from analysis if baseline data regarding their (multidimensional) burnout or fatigue status (n = 254) or their exhaustion or subjective fatigue status (n = 106) were missing. To ensure that all fatigue among the participants was unexplained, participants were excluded if they had one of the following chronic conditions that might explain fatigue complaints: cerebrovascular accident, liver dysfunction, diabetes mellitus, hyperthyroidism or cancer. In total, 11 597 participants were included in the analyses for subgroups based on burnout and fatigue, and 11 739 in the analyses for subgroups based on exhaustion and subjective fatigue.
Measures
Fatigue
The Checklist Individual Strength (CIS) was used to assess prolonged fatigue.9,10 The CIS consists of four subscales: subjective fatigue (8 items, Cronbach's 
0.93), motivation (4 items, Cronbach's 0.80), activity (3 items, Cronbach's 0.75) and concentration (5 items, Cronbach's 0.85). Items are scored on a seven-point Likert scale. Higher scores indicate higher levels of subjective fatigue, motivation, concentration or a reduced level of activity. Scores on the subscales can be added to produce a composite total score. The cut-off for classification as a fatigue case was a total score of > 76.27 Subjective fatigue cases were defined as having a score of 
35 on the subjective fatigue subscale.9
Participants were also asked to indicate whether they had fatigue complaints during the past 4 months and if so, what they thought the cause was of their fatigue complaints: a psychological cause (psychological attribution), a somatic cause (somatic attribution), or an unknown cause.
Burnout
The Dutch version of the Maslach Burnout Inventory–General Survey (MBI-GS) was used to measure burnout.15,28 The MBI-GS consists of three subscales: exhaustion (5 items, Cronbach's 0.88), cynicism (4 items, Cronbach's 0.76) and professional efficacy (6 items, Cronbach's 0.76). Originally the cynicism subscale consisted of five items, but one item did not fit well, and in line with other research, was omitted.29 All scales have a range of 0–6. Burnout cases were defined according to the Dutch MBI-GS manual as having a score higher than the 75th percentile on exhaustion (>2.4) as well as either a score higher than the 75th percentile on cynicism (>2.25) or a score lower than the 25th percentile on professional efficacy (<3.5).
Health related factors
Psychological distress was assessed using the 12-item General Health Questionnaire (GHQ-12, Cronbach's 0.89).30,31 The GHQ-12 was developed as a screening instrument for detecting minor psychiatric disorders. The traditional binary scoring method (0, 0, 1, 1) was used to define probable cases of minor psychiatric disorder. This gives a range of scores of 0–12. The cut-off for case classification was 4 or higher.32
Self-reported chronic conditions (somatic and psychological) were assessed by asking participants if they suffered from a chronic condition and if so, if they could indicate, by means of a list of 15 items, from which chronic condition they suffered.33 Based on these responses participants were classified as having a somatic and/or a psychological chronic condition.
Perceived general health was assessed with one item from the Dutch version of the Short Form Health Survey (SF-36).34,35 Participants indicated on a 5-point scale whether they thought their perceived general health was excellent (1), very good (2), good (3), moderate (4), or bad (5). This variable was dichotomized into good perceived general health (1–3) and bad perceived general health (4–5).
Work-related factors
Working hours, work schedule, managerial position (yes/no) and absenteeism were all assessed by self-report. Working hours were assessed in five categories (<16, 16–25, 26–35, 36–40, >40), which were dichotomized into two categories: full-time work (36 hours/week) and part-time work (<36 hours/week). Work schedule was assessed by asking participants if their normal working hours were between 7 am and 7 pm (yes = day work, no = shift work/irregular working hours). Self-reported sickness absenteeism was defined as being either completely or partially absent (working limited hours or able to do limited activities) in the past 4 months.
The psychosocial work characteristics of psychological job demands (5 items, Cronbach's 0.70), skill discretion (6 items, Cronbach's 0.73), decision authority (3 items, Cronbach's 0.73), decision latitude (9 items, Cronbach's 0.82), co-worker social support (4 items, Cronbach's 0.76), and supervisor social support (4 items, Cronbach's 0.85), were assessed using the validated Dutch version of the Job Content Questionnaire.36,37 Higher scores indicate higher levels on these scales.
Demographic factors
Age, gender and education were all assessed by self report.
Definition of subgroups
Four exclusive subgroups were formed based on the cut-off points for burnout and/or prolonged fatigue caseness described in the measures section: pure fatigue cases (prolonged fatigue case but no burnout case), pure burnout cases (burnout case but no prolonged fatigue case), fatigue and burnout cases (burnout and prolonged fatigue case simultaneously), and neither fatigue nor burnout cases. Similarly subgroups were also formed based on exhaustion and subjective fatigue status: pure subjective fatigue cases, pure exhaustion cases, subjective fatigue and exhaustion cases and neither subjective fatigue nor exhaustion cases.
Statistical analysis
Principal component analysis was used to determine if the CIS and MBI-GS were able to discriminate between burnout and prolonged fatigue. The CIS and MBI-GS were analysed simultaneously by means of a forced two-factor solution to determine the discriminative ability on a construct level. The CIS and MBI-GS were also analysed simultaneously with an unforced factor solution to refine these results, and to see whether and which domains can be distinguished within these constructs. An oblimin rotation was used, and the eigenvalue criterion >1 was used to extract factors. Double loadings were defined as secondary factor loadings of 0.4 or higher. Factor loadings (including cross loadings) of at least 0.3 were interpreted (the highest is interpreted in the event of an item loading on two factors). Moreover, Pearson correlations were calculated between the scales of the measures.
Kruskal-Wallis tests were used to analyse differences between the subgroups on continuous variables. To analyse differences between the groups on dichotomous or categorical variables, 
2 tests were used. All analyses used SPSS (version 12.0).
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Pearson correlations
Pearson correlation coefficients between the subscales of the CIS and MBI-GS were calculated in order to gain some insight into their associations. The correlations between the subscales were moderate to strong, ranging from 0.26 to 0.72. Notably, the strongest correlation (0.72) is between the CIS subscale subjective fatigue and the MBI-GS subscale exhaustion.
Principal component analysis
Simultaneous analysis of CIS and MBI-GS (forced two-factor solution)
To examine the ability of the CIS and MBI-GS to discriminate between two different constructs, the items of these two instruments were analysed with PCA using a forced two-factor solution (Table 1). The first factor consisted of the five exhaustion items of the MBI-GS, the eight subjective fatigue items of the CIS, the four motivation items of the CIS and four of the five concentration items of the CIS. The second factor consisted of the six professional efficacy items of the MBI-GS, the four cynicism items of the MBI-GS, one of the five items of the concentration subscale of the CIS, and the three activity items of the CIS. Items of the cynicism and professional efficacy subscales of the MBI-GS scales loaded on the second factor, whereas the exhaustion items of the MBI-GS loaded on the first factor along with the subjective fatigue, concentration, and motivation subscales of the CIS (Table 1). Moreover, the CIS activity items loaded on the second factor, although the majority of the items of the other three subscales of the CIS loaded on the first factor.
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Simultaneous analysis of CIS and MBI-GS (unforced factor solution)
PCA of the CIS and MBI-GS with an unforced factor solution yielded six factors (Table 2). The first consisted of the eight subjective fatigue items of the CIS, one motivation item of the CIS and one exhaustion item of the MBI-GS; the second captured the six professional efficacy items of the MBI-GS; the third, the three activity items of the CIS; the fourth, the five concentration items of the CIS; the fifth, four of the five exhaustion items of the MBI-GS as well as the four cynicism items of the MBI-GS; and the six, three of the four motivation items of the CIS. The results of this PCA show double loadings of one cynicism item (MBI-GS, factors 2 and 5) and one motivation item (CIS, factors 1 and 6) (Table 2). The items of the exhaustion subscale and the cynicism subscale of the MBI-GS were clustered together on one factor.
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Overlap in constructs and complaints
We looked at the extent to which the constructs of burnout and prolonged fatigue, as well as exhaustion and subjective fatigue, overlapped. We found that 63% of the burnout cases were also prolonged fatigue cases, whereas 51% of the prolonged fatigue cases were also burnout cases (specific data not shown). Moreover, 61% of the exhaustion cases were also subjective fatigue cases, and 68% of the subjective fatigue cases were also exhaustion cases (specific data not shown). There was a considerable overlap between burnout and prolonged fatigue on the one hand, and their respective main complaints exhaustion and subjective fatigue on the other (Table 3).
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Characteristics of sub-groups based on prolonged fatigue and burnout status
Table 4 shows characteristics of pure fatigue cases, pure burnout cases, fatigue and burnout cases and neither burnout nor fatigue cases. Due to the large number of participants, most of the comparisons between the groups (even small differences) on the presented variables were statistically significant.
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There were no notable differences between the subgroups in demographic factors, except for a slightly lower percentage of men in the pure fatigue group compared to the other subgroups. The most notable differences between the subgroups were in perceived general health and GHQ caseness. The proportion of GHQ-cases was highest in the fatigue & burnout group. Moreover, the proportion of GHQ-cases in the pure fatigue group was higher than in the pure burnout group. The same pattern was also observed for perceived bad general health. The pure fatigue, pure burnout and fatigue and burnout groups were quite comparable with respect to self-reported chronic conditions. Mean CIS and MBI-GS scores were higher in the fatigue and burnout group than in the pure fatigue group and the pure burnout group, respectively. Pure fatigue cases and the neither fatigue nor burnout cases reported doing day-work slightly more often than pure burnout cases and the fatigue and burnout cases. The pure burnout group and the fatigue and burnout group tended to have more unfavourable scores than the other two groups in terms of demands, skill discretion, decision authority, decision latitude and supervisor social support. Those who were both burned out and fatigued reported a higher percentage of absenteeism than any of the other groups.
Characteristics of sub-groups based on subjective fatigue and exhaustion status
In general, the same patterns emerged as with the burnout and prolonged fatigue subgroups analysis (Table 5). However, there were a few differences. There was a lower percentage of men in the pure subjective fatigue group than in the other subgroups. The difference between pure subjective fatigue and pure exhaustion in GHQ caseness frequency is smaller than between pure fatigue and pure burnout cases. Differences emerged with respect to attributions: the pure exhaustion subgroup and the subjective fatigue and exhaustion group reported a psychological attribution for their fatigue complaints more often than in the other two subgroups. Moreover, pure exhaustion cases reported less somatic attributions for their fatigue complaints than the other subgroups. Finally, only the neither subjective fatigue nor exhaustion subgroup differed from the other subgroups with respect to shift work.
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Principal component analysis
The forced two-factor PCA indicates that the discriminative ability of the CIS and the MBI-GS with respect to discriminating between burnout and prolonged fatigue on a construct level is moderate. The discriminative ability could be described as good if the CIS items and the MBI-GS items loaded on two separate factors in a forced two-factor solution as for example has been shown for the GHQ and the CIS.38 However, in our results the exhaustion items of the MBI-GS cannot be adequately discriminated from the CIS items that measure prolonged fatigue. This is not an unexpected finding as exhaustion is strongly related to (especially) the subjective fatigue component of the CIS. This finding is also in line with other research that found that the exhaustion component of burnout along with several measures of fatigue (among which the CIS) measured the same concept.8,19,20
As the CIS has four subscales and the MBI-GS three subscales, we would have expected to find seven separate factors in the unforced PCA. However, we found six factors, as the exhaustion and cynicism items of the MBI-GS load on one factor. In contrast to the forced two-factor analysis, we see that the exhaustion subscale loads on a separate factor from the subjective fatigue subscale, which could indicate a subtle distinction between subjective fatigue and exhaustion items. Taking the result together, in general the MBI-GS and the CIS can discriminate between burnout and prolonged fatigue. Although exhaustion (MBI-GS) measures the construct of fatigue it seems to be slightly different than the subjective fatigue subscale of the CIS.
Overlap
There was a considerable overlap between burnout and fatigue cases, as well as between exhaustion and subjective fatigue. However, the conditions did not overlap completely, meaning that burnout and prolonged fatigue, and exhaustion and subjective fatigue, can evidently occur as separate conditions. This is a surprising finding since exhaustion is regarded as a specific (work related) form of non-specific general fatigue.
Pure fatigue and pure burnout
Pure fatigue and pure burnout cases in this study were quite similar with respect to demographic factors and attributions. The latter finding is somewhat unexpected. Although there is a small difference, one might expect burnout cases to report a psychological attribution for fatigue complaints more often than fatigue cases, as it is thought to be a psychological condition. There were differences between the pure fatigue and pure burnout groups on several health and work-related factors. With respect to the health-related factors (i.e. GHQ cases and perceived bad general health) the pure fatigue group tended to do worse than the pure burnout group. The pure burnout group, however, tended toward more negative work conditions such as a higher percentage of shift workers, higher demands, less control and supervisor support than the pure fatigue group. This finding could support the notion that burnout is not merely fatigue but rather a specific work-related syndrome.4 Alternatively, employees might evaluate their work more negatively if their complaints are labelled as 'burnout'.
Concurrent fatigue and burnout
Being concurrently fatigued and burned out seemed to be associated with worse outcomes than having only one of these conditions. This finding was more pronounced for health-related than for work-related outcomes (absenteeism however, was higher in this group than in the other three subgroups). Mean scores on the MBI-GS and CIS dimensions indicate that the level of both prolonged fatigue and burnout is more severe in this group than in the other groups. Moreover, a high percentage (65%) of the group meeting the criteria for both prolonged fatigue and burnout also met the criteria for a GHQ case (minor psychiatric cases).
These results are in line with other research findings. One study reported that 70% of a group of severe burnout cases could be classified as psychiatric cases based on the GHQ-12.1,39 In a study aiming to examine the relationship between burnout and depressive disorders, 53% of those with severe burnout also had a depressive disorder.40 Studies on fatigue have also found considerable associations between fatigue and psychological distress.38,41 Moreover, it was found that the association increased as the severity of fatigue increased.41 Several explanations can be given for the tendency of more severe complaints to be associated with co-occurrence of other conditions. One is the possibility of a synergistic effect, causing higher scores on the CIS and MBI-GS as well as more health complaints in this group compared to the single condition groups. Another possibility could be that those who develop or have both conditions concurrently are from the outset the more severe cases, or more susceptible, and thus also tend to have higher scores on other clinical symptoms.
Subjective fatigue and exhaustion
After comparing subgroups based on subjective fatigue and exhaustion status, the same pattern emerged as with the comparison of burnout and prolonged fatigue status. However, causal attributions did differ between these groups in the expected direction. Specifically, the pure exhaustion group and the subjective fatigue and exhaustion group reported a psychological attribution for fatigue more often than the other subgroups. Moreover, the pure exhaustion group reported fewer somatic attributions for their fatigue complaints than the other subgroups. This suggests that attribution might play a role in the distinction of prolonged fatigue and burnout, as previously found by Huibers et al.25 However, in this study, attributions seem to play a role at the level of the main complaints of burnout and prolonged fatigue.
Methodological considerations
A methodological consideration when using continuous measures to examine the prevalence and overlap in burnout and prolonged fatigue cases is the use of cut-off points. The prevalence of caseness and the degree of overlap is partly dependent on the cut-off and can therefore vary according to the chosen cut-off point. Another issue is the instrument (and its underlying construct definition) used to operationalize fatigue or burnout. Using another measure for fatigue for example (with other cut-off criteria) would probably lead to a different prevalence and overlap. Non-responders at baseline were less likely to report fatigue complaints, absenteeism and difficulty in work execution. This could have led to a slight overestimation of the prevalence with respect to fatigue cases and possibly burnout cases. Overestimation of the observed associations due to the influence of common method variance (owing to the sole use of questionnaires in this study) and stable third variables such as negative affectivity cannot be ruled out.
Conclusion
Our study suggests there are some relevant differences between burnout and fatigue with respect to work and health factors, and that burnout and fatigue can occur both separately as well as simultaneously. Having both conditions simultaneously seems to be associated with worse outcomes than having either separately, particularly in terms of health-related factors such as psychological distress and self-reported general health. Pure fatigue seems to be more associated with health-related factors, whereas pure burnout seems to be more associated with work-related factors. A longitudinal study of prolonged fatigue and burnout may provide valuable information as to whether and how these differences influence their respective courses.
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Acknowledgments |
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This study was funded by the Occupational Health Epidemiology program of the Research Institute Caphri, Maastricht University, The Netherlands. The authors wish to thank W. Schaufeli for his valuable comments on the manuscript.
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