Limitations
humour, depression, fatigue, ill
There was major attrition in this study, leading to many incomplete datasets and only very few patients that were treated according to protocol, even though we had shortened and simplified assessment instruments and intervention following a pilot testing. Most randomized patients did not consent to participate in the study due to feeling fatigued or being sedated, and most of those who participated were not available for a second humour intervention as they had been discharged or transferred to another place of care. Therefore an intention-to-treat analysis was not feasible. With almost zero questionnaire data available from these patients, imputation was not possible, and an elevation of The control group did not receive an alternative intervention, due to feasibility reasons. This inactive control group setting creates the risk of performance bias. Lack of an active control also prevented adequate blinding and allocation concealment. These limitations may limit the transferability of the results. However, inclusion rates did not differ significantly between the intervention and control group, indicating a low risk of allocation bias. Methodologically, it would have been useful to set a cut-off value for cheerfulness to rule out bias by higher levels of cheerfulness in the persons who agreed to participate in the study. However, since levels of state cheerfulness did not show significant differences between intervention and control group, it can at least be assured that there was no bias due to allocation. The effect of cheerfulness on the willingness to participate might not be specific to humour interventions though, as a higher level of depression has been shown to limit the willingness to participate in any kind of study [The comparison of control and intervention group at the start of data collection showed that there was no significant difference between groups. Even though allocation was not concealed, these data seem to ensure comparability of both groups.Ethical aspects of collecting complex data with severely ill patients at the end of their lives need to be discussed [In the original study plan, we had included a semi-structured interview for day 5 of the data collection. This was only possible in very few cases due to patient discharge, fatigue, and exhaustion of patients after the data collection and interventions.