Our main results show that the course of illness, measured as symptoms of burnout, depression and anxiety in patients treated with MMT for stress-related exhaustion, was not related to sex or age. The burden of mental symptoms in this group of patients is high and is similar for female and male patients. The proportion of patients who had a high score for burnout decreased gradually over time, and the most pronounced decrease is seen at the first follow-up after three months of treatment. However, as many as one-third of the patients still reported high symptom burden after 18 months, indicating a need for further treatment. At the same time of follow-up, only one out of 10 scored above the cut-off for probable depression or anxiety, indicating a rather good effect of the treatment on the co-morbid conditions. Thus, the results indicate that this patient category, characterised by a high burden of mental and psychosomatic symptoms, often needs a long time to recover from the symptoms of burnout. This is the case even when intensive, individualised MMT at a specialised clinic is offered up to 18 months. Interestingly, this seems to apply to both sexes as well as young and old patients.
The group of patients included in this study reported burnout with extensive exhaustion and co-morbid depression and anxiety. This might explain the difference in the course of illness compared to what has been seen in previous studies, for example, in patients with adjustment disorder, which is considered to represent patients with minor mental health problems, usually without other complicating co-morbid psychiatric conditions . Thus, patients who seek care for stress-related mental health problems can differ considerably in respect of recovery and time needed for rehabilitation and this could partly be explained by the severity of mental health symptoms. In a four-year follow-up, a comparison between three groups from a working population showed that the group with combined burnout/fatigue problems had the most unfavourable course in terms of persistence of symptoms and absenteeism compared to individuals who reported only burnout or fatigue. The pure burnout group had the fastest rate of recovery . The patient group in our study seems to be more comparable to this combined burnout/fatigue group. Thus, consideration regarding the clinical characteristics of the patient group is important when estimating plausible time for recovery.
A substantial proportion of the patients still have a high score for burnout after 12 months, and the majority of these patients are still above the selected cut-off at 18 months. More studies are needed to explore this group and the plausible reason for this long-term course of illness and lack of further improvement, at least within the time frame of this study. One plausible explanation could be ongoing stress exposure or new stressors during the course of illness and rehabilitation. Furthermore, fifteen persons out of 121 who scored below the cut-off at 12 months scored above cut-off at 18 months indicating a fluctuating course, at least in some cases.
Men and women show a similar course of symptoms
Commonly, the prevalence of burnout and other stress-related complaints are higher among women than men. This has been shown in population studies in Sweden and other countries, using either the same burnout measure as in this present study or, for example, the Maslach Burnout Inventory [8–10]. This is also confirmed in our clinical work as about two-thirds of the patients referred to the clinic are women. However, we did not find any statistically significant difference between the sexes at any time point regarding the level of burnout or symptoms of depression and anxiety. Hence, in contrast with the large sex difference seen for the prevalence rate, women and men who seek medical care for stress-related exhaustion do not seem to differ substantially regarding the burden of symptoms. A slight sex difference in the decrease of symptoms during the 18 months follow-up was seen. Among women, there was a continuous and statistically significant decrease in symptoms of burnout from baseline to 12 months. There was a similar trend among men, but the decrease was only significant between baseline and follow-up after three months. This could be due to the small sample size for men. Recently a longitudinal study from Canada showed a disadvantage for women in remission of mental disorders . Similarly, in a prospective observational cohort study of patients with fatigue in primary care, male sex was positively associated with a faster recovery , a finding that is not supported by our results. One possible explanation could be a difference between the patient groups included in these studies. The present study represents the most severe cases remitted from primary care with generalised symptoms of exhaustion, cognitive weariness and extensive co-morbidity. One explanation for the lack of sex difference could thus be due to the severity of symptoms, as this is similar for both male and female patients.
Age does not predict recovery
There were no differences in symptoms of burnout, depression or anxiety at any time point measured between young and old patients in this present study, and age did not predict the recovery of burnout symptoms. It is unclear from previous literature, how and whether age predicts recovery of mental health symptoms. Similar to our data, Huibers and co-workers showed that age does not predict recovery in fatigued employees on sick leave . However, other studies have shown that higher age predicts longer recovery time until return to work due to mental disorders . Also, a better outcome with regard to remission was shown for young persons in a primary care study of patients treated for depression . There are indications that age is related to biological changes in the response to chronic stress [36, 37]. One plausible explanation for the fact that age does not matter in this study could be that the majority of the patients is between 30 and 50, and thus even if the group is divided into young and old, conceivable differences that might be present are not detected. However, we also performed additional analyses both treating age as a continuous and as a trichotomized variable, none of which showed a statistically significant association with symptom recovery regarding burnout.
Symptom duration: A significant predictor for course of illness
While recovery of mental symptoms was not associated with sex, age, education or co-morbid depression, the patients who reported symptom duration longer than one year before seeking specialist care were less likely to score below the cut-off for burnout at six and 12 months.
Remission rates were investigated in a study of depressed outpatients commencing antidepressant therapy. Higher remission rates were correlated with a lower number of previous episodes and shorter current episode duration . Our finding that the only significant predictor of course of illness in this patient group is symptom duration prior to their seeking medical care underlines the importance of early detection of patients at risk of developing stress-related exhaustion. It is quite common, in our experience, that patients with this type of health problem report that they have been experiencing symptoms for several years prior to specialist consultation. Women could be expected to seek help earlier when experiencing symptoms [36, 37]. The patients often report that they have sought medical care for somatic symptoms such as chest pain, headache or gastrointestinal problems and that they received treatment for the single symptom only. Thus, screening for stress exposure in patients seeking medical help for one or several symptoms commonly related to stress should be considered as a preventive tool for avoiding long-term sick leave.
There was no difference between women and men or young and old patients in antidepressant (AD) use, and such medication did not predict the course of burnout symptoms. Clinical observation however, confirms that the patients on AD often report subjective improvement as less irritability and fewer symptoms of anxiety and depression, which could facilitate engagement and participation in other treatments included in the MMT module, and diminish family conflicts. We can, however, not conclude from this study whether AD is beneficial for patients with ED, and randomised controlled studies are needed to explore this issue.
Methodological consideration regarding self-rating symptoms of depression and anxiety
Only 40% of the participants diagnosed with clinical depression scored above 10 on the HAD at baseline. This is in line with the previous finding from Demyttenaere and co-workers , showing that 66% of clinically depressed patients scored 'probable depressive disorder' on HAD. The large divergence between self-report and clinical diagnosis needs to be further studied, and it is clear that caution has to be exercised when using self-ratings of symptoms as an indicator of depression. A previous review on the validity of the HAD found the scale to perform well in assessing the symptom severity and caseness of anxiety disorders and depression in somatic, psychiatric and primary care patients and in the general population , but this does not seem to be the case for this patient group. If we used the cut-off of seven instead in this study, which was earlier recommended for probable depression or anxiety disorders , it seems to capture the clinical diagnosis in this patient group better as 81% of the patients with clinical depression scored above this lower cut-off.
Clinicians in general practice and occupational health services who meet patients with mental health problems due to prolonged stress-exposure need to be aware that patients with symptoms of extensive exhaustion, co-morbid depression and anxiety constitute an important subgroup in need of special attention. Pronounced exhaustion together with cognitive weariness is nevertheless the core and longest-lasting symptom. Thus, treating the depression or anxiety solely is not sufficient, and the main focus should be on symptoms of burnout as these are still present in one-third of the patients after 18 months of follow-up according to this study. Mental health problems, including burnout and exhaustion, are more frequent among women, and more women are seeking help for stress-related mental health problems. However, the sex aspect of prevalence of stress-related mental health problems does not seem to apply when considering recovery of symptoms in clinically ill patients. Clinicians should therefore expect the duration of illness in this patient group to be similar for both sexes, and similar attention should be given to patients suffering from stress-related exhaustion, irrespective of age. Early detection of possible cases of stress-related exhaustion is recommended. We have recently published a study presenting a self-rating instrument for ED . Individuals reporting ED who were still working were more likely to report a period of sick leave at the follow-up conducted two years later. We suggest that this instrument might be useful for both primary care and occupational health services for identifying a possible risk of future severe mental health problems.
Limitations and strengths
Several limitations and strengths of this study need to be discussed. One major issue which needs to be highlighted is that the present study is not a randomised treatment study. We are following patients consecutively during treatment at the clinic regarding symptoms of mental health complaints. The patients are treated according to the same model but with somewhat different components, as the MMT is individually based. The decline of symptoms over time could thus to some extent depend on different treatments within the MMT model. Different groups (such as women and men) studied could have received different treatment. We did some additional analyses to see whether there were any apparent differences between women and men or young and old patients regarding which treatments were offered. No differences were seen when comparing available information in the medical records, and we have no reason to believe that the groups differ considerably regarding participation in different treatment alternatives. One major difference could be that some, but not all, patients were taking AD, but medication did not predict recovery.
There seems to be referral bias in that persons with higher education are more inclined to ask for more specialised care when consulting their general practitioner. Thus, the patients included were mostly well educated and differed in this aspect from the general population, so inference to other groups has to be done with caution. The strength of our data set is the relatively large number of patients treated at one clinic and seen by only two senior physicians. The course of mental symptoms during such a long-term follow-up as 18 months has, to our knowledge, not previously been studied in patients treated for stress-related exhaustion.
Unfortunately the largest loss of data due to missing values on single items was on SMBQ, leading to the exclusion of thirty-eight persons from those analyses. Most commonly the item "I feel no energy for going to work in the morning" was missing. This is expected since many patients were on sick leave when filling in the questionnaire. Also, severely ill patients are more likely to give incomplete answers due to their difficulties to concentrate. The total mean SMBQ score at baseline in the missing group was somewhat higher (5.6) compared to the analysed group (5.3). This could suggest that the proportion of patients not recovered from symptoms of burnout at 18 months may be even higher than our analysis show. The complementary analyses with imputation for missing values gave support to this assumption.