Robustness of parameter and standard error estimates against ignoring a contextual effect of a subject-level covariate in cluster-randomized trials.

In experimental research, it is not uncommon to assign clusters to conditions. When analysing the data of such cluster-randomized trials, a multilevel analysis should be applied in order to take into account the dependency of first-level units (i.e., subjects) within a second-level unit (i.e., a cluster). Moreover, the multilevel analysis can handle covariates on both levels. If a first-level covariate is involved, usually the within-cluster effect of this covariate will be estimated, implicitly assuming the contextual effect to be equal. However, this assumption may be violated. The focus of the present simulation study is the effects of ignoring the inequality of the within-cluster and contextual covariate effects on parameter and standard error estimates of the treatment effect, which is the parameter of main interest in experimental research. We found that ignoring the inequality of the within-cluster and contextual effects does not affect the estimation of the treatment effect or its standard errors. However, estimates of the variance components, as well as standard errors of the constant, were found to be biased.

Influence of sleep on symptom improvement and return to work in clinical burnout.

OBJECTIVES: The current study examined the extent to which symptom improvement and full return to work occurs among clinically burnt-out employees and what the influence of concurring sleep problems is with respect to health recovery. METHODS: Fifty-nine burnt-out employees on extended sick leave assessed their symptoms for 2 weeks using an electronic diary. After 6 months, the measurements were repeated. Symptom levels were compared with those of a healthy reference group that was assessed only once. RESULTS: After 6 months, all burnout symptoms had decreased significantly, and full return to work was achieved by 37% of the burnt-out individuals. The symptom levels at 6 months of follow-up among those who had fully returned to work were similar to healthy levels and significantly lower than the levels of those still on sick leave. The persons who benefited poorly from sleep at baseline had higher exhaustion levels at follow-up than those who benefited from sleep. Trouble falling asleep and less refreshing sleep at baseline hampered eventual full work resumption. CONCLUSIONS: The results show that a significant number of clinically burnt-out employees is able to recover in a 6-month period and that sleep plays an important role both in symptom improvement and in return to work.

Electronic diary evidence on energy erosion in clinical burnout.

Burnout is generally defined as a state of severe exhaustion. So far, research has predominantly focused on relatively mild burnout in employees able to work despite their complaints. This study examines energy depletion in clinical burnout (e.g., the severest cases on extended sick leave) by comparing the diurnal patterns of fatigue and exhaustion with those of healthy individuals. Sixty clinically burned-out and 40 healthy participants kept an electronic diary for 14 days, 7 times a day, yielding a total of 8,116 diary entries. This study shows that burned-out individuals typically suffer continuously from a severe fatigue throughout the day. The resulting flattened diurnal cycles mark a stable exhaustion that is uncommon in healthy persons. The current results provide novel support for the existence of severe energy erosion in clinical burnout.

Evidence that impaired sleep recovery may complicate burnout improvement independently of depressive mood.

OBJECTIVE: This article examines recovery through sleep in relation to sleep quality, exhaustion, and depression in clinical burnout. We focus on actual recovery per night, given its relevance to burnout improvement. METHODS: Sixty clinically burned-out participants and 40 healthy controls recorded symptoms with an electronic diary for 2 weeks at random times per day. Recovery through sleep was defined as the difference in fatigue between late evening and the next morning. RESULTS: In clinical burnout, sleep quality and recovery are impaired, and depression is elevated. Poor recovery through sleep is associated with poor same-night sleep quality, clarifying the mechanisms underlying poor recovery. Individual differences in recovery though sleep were related to differences in refreshed awakening, but not to other sleep problems. Impaired recovery was also related to severity of exhaustion, but not to severity of depressive mood, indicating that, in burnout, nonprofit from sleep is a symptom of energy depletion, not a sign of depression. CONCLUSION: Impaired recovery through sleep may hamper recovery from burnout independently of the influence of depression.

Electronic momentary assessment in chronic pain II: pain and psychological pain responses as predictors of pain disability.

OBJECTIVES AND METHODS: More than 7,100 electronic diaries from 80 patients with chronic pain (mean: 89.3, range 30-115) entered multilevel analyses to establish the statistical prediction of disability by pain intensity and by psychological functioning (fear avoidance, cognitive, and spousal pain responses). We also tested the differences between pre-chronic, recently chronic, and persistently chronic pain in the prediction of disability (impaired physical and mental capacity, pain interference with activities, immobility due to pain). RESULTS: Pain intensity explained 8% to 19% of the disability variance. Beyond this psychological functioning explained 7% to 16%: particularly fear-avoidance and cognitive pain responses predicted chronic pain disorder disability; spousal responses predicted immobility better than other aspects of disability. Immobility due to actual pain occurred infrequently. When it did, however, it was better predicted by avoidance behavior in the patient and by spousal discouragement of movement than by actual pain intensity. The prediction of immobility due to pain by, respectively, avoidance behavior and catastrophizing was better in chronic pain (>6 months) and that of physical impairment by catastrophizing better in persistently chronic pain (>12 months) than in pain of shorter duration. DISCUSSION: The psychological prediction of chronic pain disorder disability was determined beyond that accounted for by pain intensity. Nonetheless, psychological functioning explained substantial variance in chronic pain disorder disability. The psychological prediction of immobility and physical impairment was stronger with longer pain duration. Patient characteristics and momentary states of disability-and in particular of immobility-should be carefully distinguished and accounted for in chronic pain disorder.

Electronic momentary assessment in chronic pain I: psychological pain responses as predictors of pain intensity.

OBJECTIVES AND METHODS: Electronic momentary assessment was employed to substantiate the relevance of psychological functioning in chronic pain. More than 7,100 electronic diaries from 80 patients with varying IASP classified types of chronic pain served to investigate to what extent fear-avoidance, cognitive and spousal solicitous and punishing pain responses explained fluctuations in pain intensity and whether patients with pre-chronic, recently chronic and persistently chronic pain differed in this regard. RESULTS: Psychological pain responses explained 40% of the total variance in pain intensity: almost 24% concerned pain variance that occurred between the CPD patients and 16% pertained to pain variance due to momentary differences within these patients. Separately tested fear-avoidance and cognitive responses each explained about 28% of the total pain variance, while spousal responses explained 9%. Catastrophizing emerged as the strongest pain predictor, followed by pain-related fear and bodily vigilance. Results did not differ with the duration of chronicity. DISCUSSION: Exaggerated negative interpretations of pain, and fear that movement will induce or increase pain strongly predicted CPD pain intensity. Spousal responses-assessed only when the spouse was with the patient who at that moment was in actual pain-may more strongly affect immobility due to pain than pain intensity per se (see part II of the study). The findings substantiate the importance of catastrophizing, fear and vigilance identified primarily in low back pain and extend this to other forms of chronic pain. The compelling evidence of momentary within-patients differences underscores that these must be accounted for in chronic pain research and practice.

Feasibility of an electronic diary in clinical burnout.

Electronic diaries overcome important drawbacks of retrospective reports and capture fluctuations of psychological states and behavior. This study represents the first use of this method in clinically burned-out participants and aims to establish its feasibility concerning participant acceptability, compliance, and reactivity in this sample. Electronic diary measurement of burnout symptoms was performed 5 times a day for 2 weeks in 60 burned-out participants on sick leave and in 40 healthy controls. The method was well accepted, compliance was high (81%-96%), and no reactivity effect was found on the recording of burnout symptoms. We conclude that the electronic diary employed is accurate, reliable, and a promising tool in capturing key symptoms and their fluctuations in clinical burnout.