The self-assessment of perceived immune status is important, as this subjective observation leads individuals to decide whether or not to seek medical help or adapt their lifestyle. In addition, it can be used in clinical settings and research. The aim of this series of studies was to develop and validate a short questionnaire to assess perceived immune functioning. Five surveys were conducted among Dutch and International young healthy adults (18–30 years old), and two others among older age groups with various health complaints. For the first study, an existing immune functioning scale was modified and elaborated resulting in 23 immune-health-related items, of which the occurrence was rated on a 5-point Likert scale. A student sample was surveyed, and the results were used to shorten the 23-item listing into a 7-item scale with a predictive validity of 85%. Items include “sudden high fever”, “diarrhea”, “headache”, “skin problems (e.g., acne and eczema)”, “muscle and joint pain”, “common cold” and “coughing”. The scale is named Immune Status Questionnaire (ISQ), and it aims to assess perceived immune status over the preceding year. The second study revealed that the ISQ score correlated significantly with a 1-item perceived immune functioning (r = 0.383, p < 0.0001). In the third study, the final Likert scale descriptors were determined (“never”, “sometimes”, “regularly”, “often” and “(almost) always)”. The fourth study showed that the test–retest reliability of the ISQ is acceptable (r = 0.80). The fifth study demonstrated the association of ISQ scores with various neuropsychological and health correlates in an international sample, including perceived health and immune fitness, as well as levels of stress, fatigue, depression and anxiety. Study 6 demonstrated significant associations between ISQ scores and experiencing irritable bowel syndrome (IBS) symptoms in a sample of insomnia patients. Study 7 compared the effect of a dietary intervention in participants reporting “poor health” versus “normal health”. It is shown that ISQ scores can differentiate between those with poor and normal health, and that an effective intervention is associated with a significant improvement in ISQ scores. Data from Study 7 were further used to determine an ISQ cut-off value for reduced immune functioning, and a direct comparison with 1-item perceived immune functioning scores enabled constructing the final scoring format of the ISQ. In conclusion, the ISQ has appropriate face, content, and construct validity and is a reliable, stable and valid method to assess the past 12 month’s perceived immune status.

Objectives Irritable bowel syndrome (IBS) and insomnia symptoms are often found to occur together. The aim of this study was to investigate the relationship between sleep and IBS complaints, and their impact on reported health and daytime functioning. Methods An online advertisement invited people with difficulty initiating and/or maintaining sleep to participate in an online survey. Sleep characteristics were assessed and the Birmingham IBS Symptoms Questionnaire was completed, including subscales on IBS-related constipation, pain, and diarrhoea. Perceived immune functioning and general health were self-rated and the lapses subscale of the Manchester Driver Behaviour Questionnaire was completed as a proxy of daytime functioning. Results Significant associations were found between sleep symptoms and IBS-related constipation, pain, and diarrhoea reports. Most sleep variables were negatively affected in subjects reporting IBS complaints, as reflected in patients reporting poorer sleep quality and less satisfaction with their sleep pattern. The associations with sleep difficulties were most pronounced for IBS-related pain. Being a woman, of younger age, and having an insomnia diagnosis were factors that were associated with having significantly more severe IBS symptoms. The association with IBS was significant for the severity of difficulty falling asleep, but not for the severity of difficulty maintaining sleep. Conclusion There is a clear relationship between sleep, perceived health, and IBS complaints. The association with IBS complaints was significant for difficulty falling asleep, but not for difficulty maintaining sleep, which may have implications for the combined treatment of sleep difficulties and IBS-related pain.

Randomized controlled trials (RCTs) have eligibility criteria for the inclusion of participants. Ideally, the RCT sample would be representative for the patient population that will use the drug under investigation. However, external validity may be at stake when applying too many or too restrictive eligibility criteria. The current two-part study examined (1) the currently applied eligibility criteria in Phase II and III RCTs examining sleep medication; (2) how these criteria match with the insomnia population as a whole; and (3) how inclusion rates can be changed by an adaptation of these criteria. In the first study, insomnia RCTs were screened at , and relevant eligibility criteria were identified. The second study comprised a survey among self-reported insomnia patients. It was determined to what extent RCT eligibility criteria match the characteristics of this patient population. Of the n = 519 patients that completed the survey only n = 2 (0.4%) met all eligibility criteria of current RCTs. RCT enrolment criteria are not representative for the insomnia patient population as a whole. Being less rigorous in applying upper or lower criteria limits results in a significant increase in the number of eligible patients, and increases the representativeness of RCTs for the insomnia patient population as a whole. The current analysis demonstrates that is important to thoroughly reconsider the use eligibility criteria and their inclusion ranges, and to have a theoretical basis for using them.

Background: Intranasal esketamine demonstrates rapid improvement of depressive symptoms. However, transient adverse effects (dissociation, sedation and dizziness) may occur, which could impact driving performance. Aims: To evaluate the effects of 84 mg intranasal esketamine on driving performance in unipolar major depressive disorder (MDD) or persistent depressive disorder (PDD) patients. Methods: The study consisted of two parts. Part A was a single-blind, double-dummy, randomized three-period, cross-over study to compare effects of esketamine versus placebo on next morning driving, 18 ± 2 h post-treatment. Alcohol was administered to demonstrate assay sensitivity. In Part B, same-day driving, 6 ± 0.5 hours post-treatment, was assessed during twice weekly esketamine administration for 3 weeks. Twenty-seven patients with mild-to-moderate MDD or PDD without psychotic features completed a 100 km on-the-road driving test on a public highway in normal traffic. The primary outcome was standard deviation of lateral position (SDLP; cm; weaving of car). Results: In Part A, alcohol impaired driving performance compared to placebo: Least-square means (95% CI), p-value for delta SDLP (cm) compared with placebo: (ΔSDLP = + 1.83 (1.03; 2.62), p < 0.001), whereas esketamine did not: (ΔSDLP = −0.23 (−1.04; 0.58), p = 0.572). In Part B, weekly driving tests showed no differences between placebo baseline SDLP and after esketamine administration over 3 weeks: Day 11: (ΔSDLP = −0.96 (−3.72; 1.81), p = 0.493), Day 18: (ΔSDLP = −0.56 (−3.33; 2.20), p = 0.686) and Day 25: (ΔSDLP = −1.05 (−3.82; 1.71), p = 0.451). Conclusions: In this study, esketamine did not impair on-road driving performance the next morning following a single dose, or on same day after repeated administration.