VALIDATION OF A QUESTIONNAIRE TO MEASURE OVERALL MEDITERRANEAN LIFESTYLE HABITS FOR RESEARCH APPLICATION: THE MEDITERRANEAN LIFESTYLE INDEX (MEDLIFE)

Abstract

Background: the Mediterranean Lifestyle index (MEDLIFE) was developed as a questionnaire to capture adherence to an overall Mediterranean healthy lifestyle. The reliability of the MEDLIFE as an independent questionnaire must be evaluated prior its use in research studies.

Objective: to assess the inter-method reliability of the MEDLIFE as a short and independent research tool.

Design: the 28-item MEDLIFE questionnaire and a 142-item validated questionnaire (full-Q) from which we derived the 28-items MEDLIFE (MEDLIFE-derived) were administered simultaneously to 196 adults (mean age 41.4 ± 9.2 y) living in Madrid, Spain. The reliability was assessed by Kappa (k) statistics, intra-class correlation coefficients (ICC) and limits of agreement (LOA).

Results: overall correlation between the two instruments was 0.626. MEDLIFE had an acceptable ability to rank participants by MEDLIFE-derived from full-Q (ICC = 0.544). Absolute agreement showed very good concordance for 10.7% of the items evaluated; good to moderate concordance for most items, and fair concordance for 32.1% of the items. Intake of sweets, processed meats, low-fat dairy products and cereals were overestimated by MEDLIFE. About 38%, 15%, 12% and 10% of participants who scored 1-point for those items in MEDLIFE also scored 1-point in the MEDLIFE-derived respectively. Bland Altman's analysis showed that LOA ranged from -4.66 to 7.45 (mean = 1.40).

Conclusion: the MEDLIFE is a valid instrument to measure overall adherence to the Mediterranean lifestyle in middle age adults from a Spanish population, and could be used as an independent questionnaire in clinical and epidemiological studies for such population. Its generalizability and predictive validity for clinical outcomes remains to be investigated.

Conflict of interest statement

Conflict of interest

All authors declare no conflict of interest

Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Figures

Fig. 1

Scatter plot of MEDLIFE by MEDLI-FE derived score (numbers of plot indicate repeat values).

Fig. 2

Bland-Altman plot indicating the mean difference between indices obtained from the full-Q and the corresponding to MEDLIFE vs the mean of the two indices.