Validation of the Psychometric Properties of the Merck Vitality Quotient: A Short Self-Questionnaire Dedicated to « Fatigue » Evaluation in Healthy Subject
International Journal of Nutrition and Food Sciences
Volume 3, Issue 6, November 2014, Pages: 515-518
Received: Sep. 2, 2014; Accepted: Sep. 30, 2014; Published: Oct. 30, 2014
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Authors
Allaert Francois-Andre, Chair for Medical Evaluation, Methodology department, ESC, Dijon, France; CEN Nutriment, Dijon, France
Courau Stephanie, Merck Medication Familiale, Medical department, Dijon, France
Forestier Anne, Merck Medication Familiale, Medical department, Dijon, France
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Abstract
Objective: validation of the psychometric properties of the Merck "vitality quotient" questionnaire (VQ) i.e. the measures of its internal consistency, external validation and sensitivity to change. Methods: Prospective observational survey conducted on patients consulting for fatigue and taking Bion3® during winter period. The VQ includes 10 questions describing subjects’ activities and mood, rated from “1: very often” to “10: never”. Its comprehensibility and test-retest reliability has been evaluated in one other study. Each patient was asked to fulfil the VQ and the Pichot scale which is a reference scale for fatigue evaluation at inclusion and every month during three months. Internal consistency of the VQ was measured with Cronbach’s alpha coefficient, external validation by its correlation coefficient with Pichot scale and its sensitivity to change by the paired T test of its average variations during the study period. Results: 132 subjects 48.2 ± 13.5 years old (63.6% women) were followed. The Cronbach’s alpha coefficient has a very high level of 0.93 and therefore indicates a very good internal consistency. The study of the VQ correlation with the fatigue scale of Pichot at baseline shows a high Pearson coefficient of r = -0.67 (p <0.0001) and the study of the correlation of their changes during the three months is of r = -0.75 (p <0.0001). The VQ is also sensitive to change. After one month the VQ increases from 47.3 ± 18.5 to 60.4 ± 20.5 and then to 73.5 ± 18.0 after 2 months and to 80.9 ± 18.1 after 3 months which is highly significant (p<0,0001) and corresponds to improvements of respectively +27.7%, +55.4% and +71.0% of the initial vitality of the subjects taking Bion3®. Conclusion: This study validates psychometrics properties (reliability, external validity and sensitivity to change) of the Merck « vitality quotient » which appears therefore as an effective tool to evaluate food supplements effects in subjects complaining of fatigue, tiredness, exhaustion and expressing a loss of vitality.
Keywords
Fatigue, Self-Questionnaire, Validation
To cite this article
Allaert Francois-Andre, Courau Stephanie, Forestier Anne, Validation of the Psychometric Properties of the Merck Vitality Quotient: A Short Self-Questionnaire Dedicated to « Fatigue » Evaluation in Healthy Subject, International Journal of Nutrition and Food Sciences. Vol. 3, No. 6, 2014, pp. 515-518. doi: 10.11648/j.ijnfs.20140306.14
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