Chronic fatigue syndrome and occupational status: a retrospective longitudinal study

Abstract

Background

Few studies into chronic fatigue syndrome (CFS) have emphasized work-related consequences, including return to work after illness.

Aims

This paper explores socio-demographic, work and clinical characteristics that are associated with occupational status among patients who were assessed at baseline and a follow-up point.

Methods

Longitudinal data were assessed from patients affected by CFS who attended an outpatient CFS treatment service between 2007 and 2014. Employment status at baseline and follow-up was available for 316 patients. Data were also included on gender, age, duration of CFS, fatigue severity, type and number of treatment sessions, coping strategies, functional impairment, common mental disorders and physical functioning.

Results

Most patients were female (73%) and had been affected by CFS for longer than 2 years (66%). Patients were followed up for an average of 285 days and over this period 53% of patients who were working remained in employment. Of the patients who were not working at baseline, 9% had returned to work at follow-up. However, of those working at baseline, 6% were unable to continue to work at follow-up. Age, fatigue severity, functional impairment, cognitive and behavioural responses, and depressive symptoms impacted on a patients’ work status at follow-up.

Conclusions

The findings indicated that it is possible for people with CFS to remain in work or return to work, despite having had a disabling illness. Work-related outcomes should be targeted in all people of working age.

Chronic fatigue syndrome, employment, mental disorders, occupation, treatment outcomes, well-being

Key learning points

What is already known about this subject:

• Chronic fatigue syndrome, also known as myalgic encephalomyelitis, is a disorder characterized by persistent or relapsing, and unexplained fatigue lasting for at least 6 months.

• Studies into chronic fatigue syndrome have placed little emphasis on work-related consequences, including return to work after illness.

What this study adds:

• Three hundred and sixteen patients attending a specialist chronic fatigue syndrome treatment service were followed up for an average of 285 days.

• Over half of the patients who were working at baseline were able to remain in work over the follow-up period and 9% returned to work. However, of those working at baseline, 6% were unable to continue to work at follow-up.

• Factors that impacted on a patient’s work status at follow-up included age, fatigue severity, functional impairment, cognitive and behavioural responses and depressive symptoms.

What impact this may have on practice or policy:

• Work-related outcomes should be targeted in chronic fatigue syndrome treatment.

• For those in work, the nature and quality of the work environment should be considered, and possible adjustments discussed.

• This needs to be done in close collaboration with the patient, their health professional, occupational health and management contacts.

Introduction

Chronic fatigue syndrome (CFS) is a disorder characterized by persistent or relapsing, and unexplained fatigue lasting for at least 6 months [1]. Previous studies have shown that the condition is associated with significant disability and dysfunction, including cognitive impairments—for example, problems with attention span and reasoning. Difficulties with mobility and housekeeping are also common [2]. Such symptoms are not only severe, but also enduring. A Danish study that followed up patients diagnosed with CFS found that only ~6% had experienced substantial recovery over a 5-year period despite participating in a wide variety of treatment programmes [3]. Factors associated with better recovery and improvement outcomes included lower levels of fatigue at baseline, feeling in control of symptoms, no psychiatric co-morbidity and people not attributing their symptoms to a physical cause [4].

Lost productivity due to CFS is substantial relative to national estimates for other major illnesses [5]. As such, occupational outcomes can be used as an important indicator of CFS prognosis. A large proportion of individuals ranging from 35% to 69% are unable to work because of CFS [2]. Taylor et al. found that patients with fatigue at follow-up were more likely to have received disability benefits or to have been working fewer hours at their initial clinical assessment, than patients whose symptoms had improved [6]. A detailed systematic review of the prognosis of CFS revealed that few individuals with CFS report returning to work once they stop paid employment [4].

Studies into CFS have placed little emphasis on occupational outcomes, including return to work after illness. While there is evidence that illness severity [7], functional impairment [8] and psychiatric co-morbidity [9], as well as a perceived lack of control over symptoms [4], play a role in occupational impairment and sickness absence, specific factors predicting CFS patients’ return to work after a period of absence have seldom been explored. This lack of research has led to a recommendation in the field to conduct further investigations into this outcome [10]. We also need to improve early treatment and rehabilitation services for those experiencing CFS [11]. Despite the importance of occupational outcomes, including return to work, for patients affected by CFS, few studies have been investigated this using longitudinal data.

The current paper examines socio-demographic, work and clinical characteristics that are associated with occupational status among CFS patients who were assessed before the start of treatment and followed up for up to 3 months after treatment discharge. Specifically, we include CFS symptom severity, functional impairment, psychological coping, anxiety and depression variables. Based on the literature, and considering factors associated with CFS recovery, we hypothesized that depression, severity of illness (defined by symptom severity and impairment) and negative beliefs and unhelpful coping strategies would be associated with remaining out of work or dropping out of work over the course of follow-up.

Methods

The current study included patients attending a CFS treatment service in the UK, who had been routinely assessed both before treatment (at baseline) and after treatment had finished (follow-up) (n = 746). A clinician confirmed the CFS diagnosis when patients visited the service. Patients fulfilled NICE criteria for CFS [12]. Patients were excluded if: (i) their CFS diagnosis was not clinically confirmed (n = 72); (ii) their baseline assessment or follow-up assessment was not completed (n = 78); (iii) they were affected by other health conditions that may have influenced their return to work, such as cancer, eating disorders, epilepsy or bipolar disorder (n = 12); (iv) they reported being retired at their baseline assessment or follow-up assessment (n = 11, of which only one patient moved from temporary sick at baseline to retirement at follow-up); (v) they indicated to be a home maker at their baseline assessment or follow-up assessment (n = 17, of which only five patients changed status at follow-up; three from temporary sick, one from permanently sick/disabled and one from student to looking after home); or (vi) they did not provide information about their occupational status at their baseline assessment or discharge (n = 48).

Patients visiting the unit for the first time were asked to fill in a questionnaire, as well as at the point of treatment discharge. The baseline data used in this project were collected between 2007 and 2014. The outcome variable of interest was employment status, based on combinations of changes in patients’ employment status between their baseline assessment and follow-up assessment. This resulted in four categories for the outcome variable: (i) working at baseline and follow-up; (ii) not working at baseline and follow-up; (iii) dropped out of work from baseline to follow-up; and (iv) returned to work from baseline to follow-up.

People who were in full-time, part-time, students or casual employment were classed as working. People who reported being unemployed, on temporary sick leave or permanently sick or disabled were classed as not working. Participants were also asked whether they were currently on sick leave and if so, for how long they had been absent from work.

The other measures used were all reliable and valid and were collected at patients’ baseline assessment: (i) the 11-item Chalder Fatigue Questionnaire (FQ)—to assess the severity of fatigue [13,14]; (ii) the 10-item Short Form Health Survey (SF-36)—to assess difficulties in physical functioning [15]; (iii) the 42-item Cognitive and Behavioural Responses Questionnaire (CBRQ)—to assess cognitive and behavioural responses to CFS [16,17]; and (iv) the five-item Work and Social Adjustment Scale (WSAS)—to assess impaired functioning [18]. Higher scores suggested worse fatigue on the FQ, more negative cognitions and unhelpful behaviours on the CBRQ and higher levels of impaired functioning on the WSAS. Poorer physical functioning on the SF-36 was indicated by lower scores. The SF-36, CBRQ and WSAS have been shown to be valid and reliable for use in patients with CFS [16,19,20]. The Hospital Anxiety and Depression Scale (HADS) was used to assess symptoms of anxiety and depression, with seven items each [21]. Scores above 10 were used as indicative of the presence of anxiety or depression. In addition, we asked the patients whether they felt their current or past job was challenging physically or mentally.

All patients participated in a treatment programme of cognitive behavioural therapy (CBT), graded exercise therapy (GET) or adaptive pacing therapy. The CBT programme focused on changing the behavioural and cognitive responses of patients that are believed to result in the continuation of their symptoms and disability. The GET programme aimed to support patients in gradually increasing their levels of physical activity [22–24]. Adaptive pacing therapy helped people to balance activities in their lives.

STATA SE 15.0 was used to analyse the data. First, we explored whether baseline characteristics differed between the patients who participated at baseline and discharge. Subsequently, we described how baseline socio-demographic, work and disease characteristics were distributed according to the four work status categories. Due to the small numbers in each category, no further (adjusted) logistic regressions were conducted. Missing data were imputed using the mean score of the individual patient but only if a measure had <25% of data missing [25]. Twenty-five patients did not fill in the questionnaire at discharge. In this case, data from their 3-month follow-up questionnaire were used, if available.

The Audit Committee of the South London and Maudsley NHS approved the study. All patients are asked to provide written consent for their data to be used at the time of their assessment. This was witnessed by a clinical member of staff.

Results

Of the 508 patients with CFS, 316 (62%) patients were included as they reported on employment status on two occasions, before and after therapy.

At baseline, 73% of the patients were female and 56% were single (Table 1). Most patients (66%) had been affected by CFS for longer than 2 years. Thirty per cent of patients reported symptoms of depression and 46% of patients reported symptoms of anxiety. Fifty-five per cent of the patients were employed at baseline. Socio-demographic and work characteristics were comparable among those who participated at baseline and discharge (Table 1). However, those who were working at baseline were less likely to have dropped out of the study. On average, patients were followed up for 285 days (standard deviation (SD) = 118.1) and received 16.5 treatment sessions (SD = 4.4) over this period (data not shown). Two hundred and eighty-five received CBT, 28 received GET and 2 received adaptive pacing therapy. One patient received both CBT and GET.

Table 1.

Socio-demographics, work and disease patient characteristics at baseline among those who participated at baseline and follow-up

	Baseline, N (%)	Follow-up, N (%)
	N = 508	N = 316
Gender, n (%)
Male	139 (27)	86 (27)
Female	369 (73)	230 (73)
Age (years), n (%)
Mean (SD)	37.7 (10.90)	37.1 (10.81)
18–39 years	283 (56)	181 (57)
>39 years	225 (44)	135 (43)
Marital status, n (%)
Single	280 (56)	172 (55)
In a relationship	220 (44)	143 (45)
Education, n (%)
None/secondary school	121 (24)	66 (21)
Polytechnic/university	383 (76)	248 (79)
CFS duration, n (%)
≤2 years	156 (34)	112 (39)
>2 years	299 (66)	177 (61)
Work reported as very physically demanding, n (%)
No, not at all/a little bit	305 (63)	197 (66)
Yes, quite a lot/very much	177 (37)	104 (35)
Work reported as requiring a lot of concentration and mental strain, n (%)
No, not at all/a little bit	64 (13)	35 (12)
Yes, quite a lot/very much	423 (87)	269 (89)
Fatigue severity (FQ) (range 0–33; median (IQR))	26 (22–30)	26 (22–30)
WSAS (range 0–40; median (IQR))	26 (18–32)	25 (17–31)
CBRQ (mean (SD))
Fear avoidance	14.0 (0.19)	14.1 (0.23)
Catastrophizing	8.2 (0.16)	7.9 (0.20)
Damage	10.8 (0.17)	10.8 (0.21)
Embarrassment avoidance	12.4 (0.26)	12.2 (0.32)
Symptom focusing	13.6 (0.23)	13.6 (0.28)
All or nothing behaviour	9.6 (0.22)	9.6 (0.28)
Avoidance/resting behaviour	13.7 (0.26)	13.6 (0.32)
Physical functioning (SF-36) (range 0–100; median (IQR))	47.5 (25–68)	50 (30–70)
Anxiety (HADS), n (%)
Case (>10)	230 (46)	145 (46)
Depression (HADS), n (%)
Case (>10)	149 (30)	89 (28)
Employment status
Not working	229 (45)	122 (39)

Numbers may not add up due to missing data. IQR, interquartile range.

Of the 316 patients with CFS, 119 reported that they were on sick leave from their job (38%) at baseline. The mean duration of sickness absence among those who reported to be working was 4.6 months (SD = 4.23). Among those working at baseline, 51% were in full-time employment (data not shown).

Between baseline and follow-up, older people were more likely to have dropped out of work and younger people were more likely to have returned to work (Table 2). Those higher on avoidance, all or nothing behaviours and beliefs relating to fear avoidance, damage beliefs and catastrophizing, were more likely not to be working at baseline and follow-up. No difference in work status was identified by gender, CFS duration, anxiety symptoms or the number of treatment sessions patients had attended. Patients who reported being more fatigued were more likely to remain out of work or to have dropped out of work. Patients who met criteria for anxiety and depression were more likely to have dropped out of work.

Table 2.

Baseline socio-demographic, work and disease patient characteristics by work status at follow-up (N = 316)

	Working at baseline and follow-up	Not working at baseline and follow-up	Dropped out of work at follow-up	Returned to work at follow-up	P-value#
	N = 167 (53%)	N = 104 (33%)	N = 18 (6%)	N = 27 (9%)
	N (%)	N (%)	N (%)	N (%)
Gender, n (%)					NS (Fisher’s exact)
Male	50 (30)	23 (22)	7 (39)	6 (22)
Female	117 (70)	81 (78)	11 (61)	21 (78)
Age (years), n (%)
18–39 years	107 (64)	50 (48)	7 (39)	17 (63)	<0.05 (Fisher’s exact)
>39 years	60 (36)	54 (52)	11 (61)	10 (37)
Marital status, n (%)					<0.05 (Fisher’s exact)
Single	80 (48)	69 (66)	8 (44)	15 (56)
In a relationship	86 (52)	35 (34)	10 (56)	12 (44)
CFS duration, n (%)					NS (Fisher’s exact)
≤2 years	62 (41)	33 (33)	7 (41)	10 (45)
>2 years	89 (59)	66 (67)	10 (59)	12 (55)
Work reported as very physically demanding, n (%)					<0.001 (Fisher’s exact)
No, not at all/a little bit	125 (77)	44 (47)	13 (72)	15 (56)
Yes, quite a lot/very much	38 (23)	49 (53)	5 (28)	12 (44)
Fatigue severity (FQ) (range 0–33; median IQR))	24 (21–29)	29 (24–32)	28 (25–28)	25 (21–29)	<0.001 (test of medians)
WSAS (range 0–40; median (IQR))	20 (13–26)	31 (26–34)	28 (25–32)	23 (18–31)	<0.001 (test of medians)
CBRQ, mean (SD)
Fear avoidance	13.3 (3.9)	15.3 (4.0)	14.8 (4.3)	14.2 (5.1)	<0.001 (test of means)
Catastrophizing	7.5 (3.5)	8.5 (3.5)	9.0 (4.5)	7.6 (3.6)	0.051 (test of means)
Damage	10.2 (3.8)	11.5 (3.7)	11.7 (3.9)	11.4 (3.6)	<0.05 (test of means)
Embarrassment avoidance	11.7 (5.5)	12.7 (6.3)	12.7 (6.3)	13.4 (4.4)	NS (test of means)
Symptom focusing	13.4 (4.9)	13.6 (5.0)	13.2 (6.3)	14.9 (4.5)	NS (test of means)
All or nothing behaviour	8.9 (5.0)	10.4 (4.7)	8.9 (3.9)	11.5 (5.4)	<0.05 (test of means)
Avoidance/resting behaviour	12.2 (5.2)	15.5 (5.8)	12.7 (5.6)	15.7 (5.2)	<0.001 (test of means)
Physical functioning (SF-36) (range 0–100; median (IQR))	60 (45–75)	30 (17–55)	48 (38–60)	50 (30–70)	<0.001 (test of medians)
Anxiety (HADS), n (%)					NS (Fisher’s exact)
Case (>10)	72 (44)	52 (50)	10 (56)	11 (41)
Depression (HADS), n (%)					<0.001 (Fisher’s exact)
Case (>10)	25 (15)	46 (45)	11 (61)	7 (26)

IQR, interquartile range.

^#Fisher’s exact used if value <10 in a cell, otherwise chi-square test used.

Return to work was more frequently reported among patients who experienced better physical functioning (as measured by the SF-36), and who experienced less functional impairment. Patients who reported physically demanding work were more likely to return to work compared to those who dropped out of work or remained in work. Patients who remained in work were more likely to be in a relationship, and to report better health overall—that is, less depressive symptoms, better physical functioning, less fatigue and less functional impairment (as measured by WSAS).

Discussion

This study contributes to the literature examining occupation in the context of CFS. We found that most patients with CFS who were working at baseline remained in work at follow-up. Unsurprisingly, those who reported better health stayed in work. Those patients who were not working at baseline were also more likely not to be working at follow-up. Factors associated with not working at both time points were more extreme cognitive and behavioural responses, depression and more severe fatigue. About 9% of individuals who were not working at baseline had returned to work at follow-up. Those who returned to work were functioning better and were younger. Caution is needed however, as the number of patients who returned to work was small. Further, 6% of those working at baseline were no longer working at follow-up. When interpreting these findings consideration must be made of job opportunities and employers’ willingness to be flexible regarding gradual return to work schemes.

Overall, these findings are largely in keeping with previous research [4,7,9]. The 9% of patients returning to work in this study is heartening and suggests that people can recover, as previously found in both randomized controlled trials [24] and routine clinical practice [26]. These findings suggest that there is some room for optimism in terms of CFS improving to such an extent that a return to employment is possible for a small, but significant number of patients.

Unhelpful beliefs such as fear of activity and exercise and concerns about causing damage, combined with all or nothing behaviour and behavioural avoidance, were associated with not working and are specifically targeted in CBT and, to some extent, GET. Worries relating to returning to work could be explored more explicitly in therapy, where links between coping responses and the possibility of meaningful occupation could be made. Co-morbid psychiatric conditions that run alongside CFS, especially depression, should be identified and treated appropriately. Employees affected by CFS may benefit from a clinical assessment from a specialist.

This cohort of patients is likely to be representative of those seen in a specialist clinic for CFS. However, the sample may not represent those seen in primary care, those who decline CBT and GET, or are unable to attend an outpatient clinic whether for health or other reasons. The number of people returning to work or stopping work was small, so conservative interpretation is needed. However, evidence suggests that re-employment leads to improved self-esteem and better mental health [27]. It would be interesting to elicit whether any changes in work status were stable long term. Follow-up data were only available for 60% of the sample, so caution is needed with interpretation of the data as it is possible that patients with poorer outcomes were less likely to be followed up. However, when comparing the characteristics of the baseline and follow-up sample, they were comparable, except for baseline occupational status. It is also important to note that there was a large variation in the duration of follow-up among patients (285 days; SD = 118) as this was driven by when patients were discharged from the clinic. Despite the methodological concerns mentioned, results from our sample address the dearth of studies examining occupation in the context of treatment for CFS.

Given the evidence that meaningful occupation is important for well-being and psychosocial needs [27], work-related outcomes should be targeted in CFS treatment. Overall, the beneficial effects of work outweigh the risks and are greater than the harmful effects of long-term sickness absence. For those people who are in work, issues related to occupational stress should be explored by an occupational health (OH) professional or through CBT to maximize the chances of them remaining at work. Account must be taken of the nature and quality of the work environment. Issues such as the importance of taking breaks, the consequences of consistently working long hours and managing workload could be addressed. Adjustments such as working from home, reducing workload or offering support or additional support for tasks that appear to worsen fatigue should be suggested.

The role of OH cannot be overemphasized. We previously trained OH physicians and nurses in treating fatigue in the workplace. General knowledge of fatigue and confidence in fatigue management in OH settings improved after training [28]. In the OH setting, advice and education may be important interventions to support people with early symptoms of CFS from developing coping mechanisms which seem to be associated with more chronic symptoms and disability. However, if this is insufficient, referral to a specialist centre for CFS or assessment for CBT or GET [29] may be necessary. A gradual return to work needs to be carefully negotiated by the CFS patient, their health professional and their OH and management contacts. People with CFS are likely to be covered by the disability remit of the Equality Act 2010, which requires employers to make reasonable adjustments to work and premises.

Our evaluation has limitations. It was an evaluation of occupation in people with CFS before and after treatment in a naturalistic setting and was not part of a randomized controlled trial. We used patient report outcomes with no objective measures but in this context patient perception is all important as the illness is defined by the presence of symptoms and their impact. Just over 62% of those assessed provided follow-up data thus introducing bias. Nevertheless, we have shown that although it is possible for people with CFS to get back to or re-enter work, despite having had a disabling illness many people remain unable to work. Though there is room for some optimism, this important factor needs further research. Work-related outcomes should be targeted routinely but in particular when the individual values work and is keen to return.

Funding

This paper represents independent research part funded by the National Institute for Health Research Maudsley Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London and Applied Research Collaboration South London at King’s College Hospital NHS Foundation Trust and a National Institute for Health Research Advanced Fellowship [ref: 300592]. N.T.F. is part funded by a grant from the UK Ministry of Defence. The views expressed are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research, the Department of Health and Social Care or the UK Ministry of Defence.

Competing interests

T.C. has received royalties from Sheldon Press and Constable and Robinson. She has delivered workshops on persistent physical symptoms and fatigue in the context of long-term conditions. She is the author of self-help books on fatigue. N.T.F. is a specialist member of the Independent Group Advising on the Release of Data for NHS Digital and a trustee of a charity supporting the well-being of serving personnel, veterans and their families. M.H. is a National Institute for Health Research (NIHR) Senior Investigator. S.A.M.S and K.M.M. do not have any competing interests to report.