The context dependency of the self-report version of the Strength and Difficulties Questionnaire (SDQ): a cross-sectional study between two administration settings.

BACKGROUND: The Strength and Difficulties Questionnaire (SDQ) is a screening instrument for psychosocial problems in children and adolescents, which is applied in "individual" and "collective" settings. Assessment in the individual setting is confidential for clinical applications, such as preventive child healthcare, while assessment in the collective setting is anonymous and applied in (epidemiological) research. Due to administration differences between the settings it remains unclear whether results and conclusions actually can be used interchangeably. This study therefore aims to investigate whether the SDQ is invariant across settings. METHODS: Two independent samples were retrieved (mean age = 14.07 years), one from an individual setting (N = 6,594) and one from a collective setting (N = 4,613). The SDQ was administered in the second year of secondary school in both settings. Samples come from the same socio-geographic population in the Netherlands. RESULTS: Confirmatory factor analysis showed that the SDQ was measurement invariant/equivalent across settings and gender. On average, children in the individual setting scored lower on total difficulties (mean difference = 2.05) and the psychosocial problems subscales compared to those in the collective setting. This was also reflected in the cut-off points for caseness, defined by the 90th percentiles, which were lower in the individual setting. Using cut-off points from the collective in the individual setting therefore resulted in a small number of cases, 2 to 3%, while ∼10% is expected. CONCLUSION: The SDQ has the same connotation across the individual and collective setting. The observed structural differences regarding the mean scores, however, undermine the validity of the cross-use of absolute SDQ-scores between these settings. Applying cut-off scores from the collective setting in the individual setting could, therefore, result in invalid conclusions and potential misuse of the instrument. To correctly apply cut-off scores these should be retrieved from the applied setting.

Need for recovery from work in relation to age: a prospective cohort study.

PURPOSE: To investigate the impact of increasing age on the need for recovery (NFR) over time among day workers METHODS: The study is based on data from the first 2 years of follow-up of the Maastricht Cohort Study (n = 7,734). To investigate whether age predicted the onset of elevated NFR, multivariate survival analyses were conducted RESULTS: The highest levels of NFR were observed in the age group of 46-55 years. The relative risk for developing elevated NFR was highest in the age groups 36-45 years (RR 1.30; 1.07-1.58) and 46-55 years (RR 1.25; 1.03-1.52) in men and 46-55 years (RR 1.36; 1.04-1.77) in women when compared to the reference group CONCLUSIONS: While NFR increased with age until the age of 55, this was followed by decreased levels of NFR among older employees. Explanations for the decreasing levels of NFR in the highest age group can be found in several domains such as the work environment, private situation and compensation strategies.

Psychological job demands as a risk factor for common cold in a Dutch working population.

OBJECTIVE: We investigated the effect of Psychological Job Demands (PJD) on the occurrence of the clinical symptoms of common cold. METHODS: Subjects, participating in a large prospective cohort study on psychological determinants of fatigue at work, were asked to fill in a questionnaire on the occurrence of common cold during the previous four months. High PJD were considered as a potential risk factor. Other factors such as age, gender, and having young children were considered as potential confounders. RESULTS: In logistic regression analysis, the adjusted odds ratio (OR) for having a recent cold in subjects reporting high PJD vs. those reporting low PJD was 1.20 (95% confidence interval (CI), 1.08-1.33). A higher risk emerged among those with young children (OR, 1.70; 95% CI, 1.47-1.96), those having a history of asthma (OR, 1.69; 95% CI, 1.28-2.22), or being under the age of 40 (OR, 1.28; 95% CI, 1.14-1.43) and among smokers (OR, 1.23; 95% CI, 1.09-1.38). CONCLUSION: The results support an association between PJD and common cold. In spite of the almost inevitable shortcoming of a large cohort study using questionnaires, this study gave us the opportunity to study the relationship between common cold and work-related factors in a nonexperimental setting with participants observed in a natural environment with all the normal everyday hassles.

Associations between infections and fatigue in a Dutch working population: results of the Maastricht Cohort Study on Fatigue at Work.

The relationship between fatigue and common infections was further explored, as part of a 3 year prospective cohort study on Fatigue at Work. The current study is based on seven successive questionnaires, covering the first 2 years of follow-up. The overall response at baseline was 45% (n = 12,140). On T1 10,592 (87.2% compared to baseline response) employees returned the questionnaire. For T2, T3, T4, T5 and T6, 10,270 (84.6%), 9655 (79.5%), 8956 (73.8%), 8692 (71.6%) and 8070 (66.5%) employees respectively returned the questionnaire. Self-administered questionnaires were used to determine the level of fatigue with the Checklist Individual Strength (CIS) and the occurrence of common cold, flu-like illness and gastroenteritis. Regression analysis using generalized estimated equations (GEE) were used for data analysis. We found a cross-sectional relationship between fatigue and the infections flu-like illness and gastroenteritis, and a longitudinal relationship between an infection as a predictor of fatigue. For fatigue as a predictor of an infection, we found odds ratios (ORs) of 1.35 (confidence interval (CI) 1.28-1.42) for flu-like illness and 1.33 (CI: 1.25-1.42) for gastroenteritis. The highest incidence of infections was found among employees who reported high fatigue levels on two successive occasions. The increased incidence of infections, is regarded as a substantial effect of fatigue because it is associated with significant absenteeism from work and leads to discomfort.