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Background: Generic quality of life (QoL) instruments provide important measures of self-reported wellbeing that can be compared across healthy and clinical populations. The aim of this analysis is to validate the ten-item QoL instrument "QOL10", as well as to confirm the validity of the embedded "QOL5" questionnaire and single-item "QOL1" in measuring overall QoL among adults in a substance use disorder treatment study.Methods: We used exploratory factor analysis and measured internal and convergent validity of the QOL10 against the gold standard measure of the WHOQOL-BREF, in a subsample of 107 participants in a substance use disorder treatment study.Results: The QOL10 displayed internal and convergent validity to the gold standard measure. Factor analysis revealed a two-factor structure that can be interpreted as "social QoL", containing items about relationships and social functioning, and "global QoL", comprised of items about health, working ability, self-evaluation, and an overall QoL estimation.Conclusions: The QOL10 provides clinically useful and valid measures of social-related QoL and global QoL via two subscales. Interestingly, the QOL10's social QoL measure, from the current sample, had little relationship to the analyzed groups previously reported to have differential global QoL: social QoL appears to be not only conceptually distinct from global QoL, but also to be less influenced by typical substance- and treatment-specific factors. [ABSTRACT FROM AUTHOR]

Background: To create and find accurate and reliable instruments for the measurement of physical activity has been a challenge in epidemiological studies. We investigated the reliability and validity of two different physical activity questionnaires in 71 adolescents aged 13-18 years; the WHO, Health Behaviour in Schoolchildren (HBSC) questionnaire, and the International Physical Activity Questionnaire (IPAQ, short version). Methods: The questionnaires were administered twice (8-12 days apart) to measure reliability. Validity was assessed by comparing answers from the questionnaires with a cardiorespiratory fitness test (VO2peak) and seven days activity monitoring with the ActiReg, an instrument measuring physical activity level (PAL) and total energy expenditure (TEE). Results: Intraclass correlation coefficients for reliability for the WHO HBSC questionnaire were 0.71 for frequency and 0.73 for duration. For the frequency question, there was a significant difference between genders; 0.87 for girls and 0.59 for boys (p < 0.05). The intraclass correlation coefficients the IPAQ varied between 0.10 and 0.62 for the reliability. Spearman correlation coefficients for validity for both the WHO HBSC questionnaire and the IPAQ (recoded into low, moderate and high activity) measured against VO2peak were fair, ranging between 0.29 - 0.39. The WHO HBSC questionnaire measured against VO2peak for girls were acceptable, ranging between 0.30 - 0.55. Both questionnaires, except the walking question in IPAQ, showed a low correlation with PAL and TEE, ranging between 0.01 and 0.29. Conclusion: These data indicate that the WHO HBSC questionnaire had substantial reliability and were acceptable instrument for measuring cardiorespiratory fitness, especially among girls. None of the questionnaires however seemed to be a valid instrument for measuring physical activity compared to TEE and PAL in adolescents. [ABSTRACT FROM AUTHOR]

In the original publication of this article [1] the author Marc Du Bois was omitted. In this correction article the author and the corresponding details are provided. The publisher apologizes to the readers and authors for the inconvenience. [ABSTRACT FROM AUTHOR]

Background: To assess cross-cultural validity between Dutch and English versions of the FVQ_CYP, a patient-reported outcome measure developed in the United Kingdom (UK) for children and adolescents with (severe) visual impairment or blindness (VI for brevity) to measure functional vision.Methods: The 36-item FVQ_CYP was translated and adapted into Dutch using standard guidelines. The questionnaire was administered to Dutch children and adolescents aged 7-17 years (N = 253) with impaired vision (no restrictions regarding acuity). Data were compared to existing UK data of children and adolescents aged 10-15 years (N = 91) with VI (acuity LogMar worse than 0.48). As with the original UK FVQ_CYP validation, a rating scale model (RSM) was applied to the Dutch data.Results: Minor adaptations were needed in translation-rounds. Significant differences in item responses were found between the Dutch and UK data. Item response theory assumptions were met, but fit to the RSM was unsatisfactory. Therefore, psychometric properties of the Dutch FVQ_CYP were analysed irrespective of the original model and criteria used. A graded response model led to the removal of 12 items due to missing data, low information, overlapping content and limited relevance to Dutch children. Fit indices for the remaining 24 items were adequate.Conclusions: Differences in population characteristics, distribution of responses, non-invariance at the model level and small sample sizes challenged the cross-cultural validation process. However, the Dutch adapted FVQ_CYP showed high measurement precision and broad coverage of items measuring children's functional vision. The underlying reasons for differences between countries in instrument performance are discussed with implications for future studies. [ABSTRACT FROM AUTHOR]