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Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience
Nutrition, Metabolism & Cardiovascular Diseases (2018) xx, 1e8
Available online at www.sciencedirect.com
Nutrition, Metabolism & Cardiovascular Diseases journal homepage: www.elsevier.com/locate/nmcd
Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience P. Gnagnarella a,*, D. Dragà a, A.M. Misotti b, S. Sieri c, L. Spaggiari d,e, E. Cassano f, F. Baldini g, L. Soldati h, P. Maisonneuve a a
Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy UOSD Dietologia e Nutrizione Clinica, ASST Melegnano e Martesana, Italy c Department of Research, Epidemiology and Prevention Unit, Fondazione IRCSS Istituto Nazionale dei Tumori, Milan, Italy d Department of Thoracic Surgery, European Institute of Oncology, Milan, Italy e Department of Oncology and Emato-Oncology, University of Milan, Milan, Italy f Breast Imaging Division, European Institute of Oncology, Milan, Italy g Division of Melanoma, Sarcoma and Rare Cancer, European Institute of Oncology, Milan, Italy h Department of Health Sciences, University of Milan, Milan, Italy b
Received 12 March 2018; received in revised form 11 June 2018; accepted 11 June 2018 Handling Editor: A. Siani Available online - - -
KEYWORDS Mediterranean diet; Validation study; Questionnaire
Abstract Background and aims: A greater adherence to the Mediterranean diet has been associated with a reduced risk of major chronic diseases and cancer. The aim of the study was to assess the validity of a new short self-administered 15-item questionnaire (QueMD) to measure adherence to the Mediterranean diet in Italy. Methods and results: Four-hundred and eighty three participants to cancer-screening programmes at the European Institute of Oncology, Milan (Italy) were invited to join this study. Those interested compiled the QueMD and a validated Food Frequency Questionnaire (FFQ) reporting their usual food consumption during the previous six months. We derived the alternate Mediterranean score (aMED) from both questionnaires with values ranging from 0 (minimal adherence) to 9 (maximal adherence). Complete dietary data were available for 343 individuals (participation rates 71.0%). Spearman correlation coefficient between the responses to the 15 questions of the QueMD and corresponding food intake derived from the FFQ ranged from 0.15 to 0.84. A moderate correlation was found between the aMED scores calculated from the QueMD and the FFQ (intraclass correlation coefficient 0.50; 95% CI, 0.42e0.58), while agreement between the two instruments was only poor to fair for 7 of the 9 single items composing the aMED score, with values ranging from 53.0% for wholegrain products to 79.5% for fruits. Conclusion: This new self-administered 15-item questionnaire could be a useful tool to assess adherence to the Mediterranean diet in the Italian population. ª 2018 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.
* Corresponding author. Divisione di Epidemiologia e Biostatistica, Istituto Europeo di Oncologia, Via Ripamonti 435, 20141 Milan, Italy. E-mail address: [email protected] (P. Gnagnarella). https://doi.org/10.1016/j.numecd.2018.06.006 0939-4753/ª 2018 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
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P. Gnagnarella et al.
Introduction The Mediterranean diet represents a healthy dietary pattern indicated for the prevention of non-communicable diseases, being associated with better general health status and longer lifespan [1,2]. It has been acknowledged as an Intangible Cultural Heritage of Humanity by UNESCO in 2013 (https://ich.unesco.org/en/RL/mediterranean-diet00884), and is defined as a dietary pattern common in countries around the Mediterranean basin, rich in foods of vegetable origin (cereals, fruits, vegetables, legumes, nuts, seeds), with olive oil as the principal source of fat, with moderate consumption of fish and seafood, eggs, poultry and dairy products, alcohol (mainly wine) and low consumption of red meat and meat product [3]. In addition to the evaluation of food patterns by means of factorial analysis, principal component analysis or cluster analysis (a posteriori method), more recently, many indexes or scores to measure the adherence to Mediterranean diet have been developed [4]. They attempt to evaluate the overall quality of the diet based on a pattern defined a priori [5]. They combine and weight foods and/or nutrients consumption, converting them into a single score that describes people’s health diet [6,7]. A single method to measure adherence to Mediterranean diet does not exist, mainly because its definition is not universal, being influenced by socio-cultural, religious and economic factors [3]. Differences between the various Mediterranean diet scores proposed are mainly determined by the selection of the variables or components and the different cutoff points or scoring algorithms adopted [8]. However, the use of food frequency questionnaires (FFQs) is strongly recommended to evaluate with accuracy food pattern and quality of diet. FFQs collect information on consumption frequencies and portion size for a broad list of foods and beverages, typically including from 80 to
200 food items, to assess the total diet. These instruments are very useful to determine the dietary intake in term of single nutrients, single foods and food groups, but they are time-consuming, requiring complex data management and processing, and consequently are usually expensive and unsuitable for experimental or observational studies [9]. In time-limited settings, such as intervention or epidemiological studies, alternative instruments for a rapid assessment of the diet are needed. In the context of the 7th examination of the Framingham Offspring Cohort, Rumawas et al. proposed the Mediterranean-Style Dietary Pattern Score (MSDPS) for characterizing dietary patterns, following the principles of the Mediterranean diet [10]. More recently, a Mediterranean Diet Adherence Screener was developed and validated for the PREDIMED study, a multicenter clinical trial aimed to assess the effect of the traditional Mediterranean diet for the prevention of cardiovascular disease in a Spanish population [11]. Short questionnaires have also been recently proposed and validated in other countries [12,13]. To our knowledge, only one short questionnaire to measure adherence to the Mediterranean diet has been developed in Italy [14]. However, this 9-item literaturebased instrument, administered by trained personnel, has only been validated against another short 11-item diet score developed in Greece [15], limiting the overall value of the validation. In the context of the COSMOS study (Continuous Observation of Smoking Subjects), a screening programme for the early diagnosis of lung cancer in high-risk population, we previously studied the association between dietary intake and lung cancer risk using a FFQ. We found that high adherence to Mediterranean diet was associated with a reduced risk of lung cancer [16]. This finding reinforces the importance of this dietary pattern for the prevention of forms of cancer for which the evidence is
Table 1 Characteristics of the participants in the cancer screening groups.
Total Gender Men Women Age (years) Mean SD <50 50-59 60-69 70þ BMI (kg/m2) Mean SD Underweight Normal weight Overweight Obese
All N (%)
Lung cancer screening N (%)
Dermatological control N (%)
Breast cancer screening N (%)
343 (100)
133 (100)
102 (100)
108 (100)
117 (34.1) 226 (65.9)
82 (61.7) 51 (38.3)
35 (34.3) 67 (65.7)
e 108 (100)
57.6 10.5 60 (17.5) 115 (33.5) 136 (39.7) 32 (9.3)
63.9 4.6 e 29 (21.8) 88 (66.2) 16 (12.0)
48.7 12.5 57 (55.9) 21 (20.6) 19 (18.6) 5 (4.9)
58.4 7.1 3 (2.8) 65 (60.2) 29 (26.9) 11 (10.2)
24.2 3.8 6 (1.7) 210 (61.2) 102 (29.7) 25 (7.3)
25.8 3.8 1 (0.8) 59 (44.4) 54 (40.6) 19 (14.3)
22.9 3.2 2 (2.0) 75 (73.5) 22 (21.6) 3 (2.9)
23.5 3.6 3 (2.8) 76 (70.4) 26 (24.1) 3 (2.8)
Abbreviations: SD, Standard deviation; BMI, Body mass index.
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
Validation of a questionnaire to record Adherence to the Mediterranean Diet
still weak. As traditional diet in Mediterranean countries is also changing [17], short validated questionnaires for rapid and repeated assessments of the Mediterranean diet are needed. Therefore, the aim of this study was to validate of a new short self-administered questionnaire to measure adherence to Mediterranean diet in the Italian population. Methods Study population For this validation study, we approached 483 consecutive healthy participants to cancer-screening programmes (mammography for breast cancer, low-dose computed tomography for lung cancer and dermatological check-up for skin cancer) at the European Institute of Oncology (IEO) in Milan, Italy, between May 2014 and June 2015 (Table 1). Subjects were invited to participate to the study during their screening visit. Those interested received an informed consent form and the study questionnaires with the instruction to report their usual diet in the past six months. Only those who signed the consent form and returned the study questionnaires compiled were included in the study. Ethical approval was obtained from the Ethics Committee of the IEO (R53/ 14eIEO 60). Questionnaire to measure Mediterranean diet (QueMD) We developed a self-administered 15-item questionnaire to measure the adherence to Mediterranean diet (QueMD). We included questions for the nine food items usually considered as key components of the Mediterranean diet (wholegrain cereals, raw or cooked vegetables, legumes, fresh fruits, dried fruits, red or processed meat, fish, wine and olive oil), using two separate questions to assess the consumption of wholegrain cereals (wholegrain pasta or rice and wholegrain bread and substitutes). We included additional items, such as the consumption of white meat (chicken, turkey, and rabbit). We decided to explore the consumption of dairy products, focusing only on milk and yogurt (excluding cheese), due to the different portion size of these items and the contrasting effect of different dairy products on cancer risk (i.e., protective for colon, risk for prostate) [18,19]. Finally we included questions for three additional food groups that are not typical of the Mediterranean diet: carbonated and/or sugar sweetened beverages (soft drinks); butter, margarine or cooking cream; and manufactured sweets, pastries and cakes. For each of the 15 food items, responders can choose between five consumption levels ranging from “never or seldom” to a high frequency. The food items were ordered according to their consumption frequency: daily for wholegrain cereals, vegetables, fruits, dairy products, olive oil, butter and wine, or weekly for red and white meat, soft drinks, sweets, fish, dried fruit and pulses. For each question, a standard portion [20] was indicated to help
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reporting consumption as correctly as possible. The questionnaire is available in Supplemental Table 1. EPIC food frequency questionnaire Participants also completed a validated FFQ [21]. This questionnaire developed for the European Prospective Investigation into Cancer and Nutrition (EPIC) study has been regularly used as reference method for estimating the habitual diet in terms of foods and nutrients. It contains 248 questions about 188 different food items, covering 14 sections representing the different courses of a meal. Responders should indicate how many times they consume a given food item (per day, week, month or year) and choose between a selection of images or predefined standard portions, to indicate the food quantity. An ad-hoc software converts collected data into average daily intakes of foods, energy and nutrients [22]. Conversion from foods to nutrients is based on the Italian food composition database that was specifically developed for epidemiological studies [23]. Scoring system for the alternate Mediterranean diet (aMED) in the QueMD and EPIC-FFQ We calculated the aMED score ranging from 0 (minimal adherence to Mediterranean diet) to 9 (maximal adherence) from both questionnaires (QueMD and EPIC-FFQ) following the method proposed by Trichopoulou et al. [24] and successively modified [2,25]. The aMED score from the short QueMD was calculated assigning 1 point to participants reporting consumptions above the average Italian National levels [26] for each of the following foods that are characteristic of the Mediterranean diet [27]: vegetables (2/day), fresh fruits (2/ day), dried fruits (2/week), wholegrain cereals (1/day), pulses (2/week), fish (2/week) and olive oil intakes (3/day). We also assigned 1 point to those consuming red and processed meat 1e3/week and 1 point for men drinking 1e2 glasses of wine per day or women drinking limited amount of wine (>0 < 1/day) (Table 3). The aMED score from the EPIC-FFQ was calculated adding 1 point if the consumption of selected foods was above or below the sex-specific median value of consumption reported by all study participants; vegetables (M > 229.4 g; F > 239.6 g), fruits (M > 282.3 g; F > 311.3 g), nuts (M > 6.5 g; F > 5.3 g), wholegrain cereals (M > 12.0 g; F > 20.1 g), pulses (M > 14.1 g; F > 12.2 g), fish (M > 37.4 g; F > 37.6 g) or olive oil (M > 30.3 g; F > 26.1 g), red and processed meat (M < 7.8 g; F < 62.6 g); finally 1 point was given if wine consumption was comprised between 125 and 250 ml (corresponding to 1e2 glasses/day) for men or between 62.5 and 125 ml (corresponding to 1/2-1 glass/day) for women (Table 3). An alternative score was constructed using mean daily consumptions reported in a large National Italian Survey (IRAN-SCAI 2005e2006) [28,29] instead of the median consumption reported in our study (Supplementary Table 3).
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
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P. Gnagnarella et al.
Table 2 Spearman correlation between responses to the 15 items included in the QueMD and corresponding daily consumption recorded by the EPIC-FFQ. Food Items
1. Wholegrain pasta or rice 2. Vegetables, all type (raw and cooked) 3. Fruits, all types fresh and fresh juices 4. Milk and yoghurt
5. Wholegrain bread and substitutes 6. Olive oil to cook and to dress 7. Butter, margarine or cooking cream 8. Wine (white and red)
9. Red meat (beef, veal, pork), meat products
10. White meat (chicken, turkey, rabbit) 11. Carbonated and/or sugarsweetened beverages 12. Manufactured sweets, pastries, biscuits, creams.
13. Fish (fresh or frozen) or sea foods 14. Dried fruits (nuts, almonds, hazelnuts) 15. Pulses (chickpeas, lentils, peas, beans)
QueMD (Frequency of consumption) Reference portions
Never or seldom
<1 per day
1 per day 2 per day 3 per day
EPIC-FFQ (g/day) Mean SD
80 g 200 g 80 g (salad) 150 g
48.4% 0.6%
30.9% 13.1%
19.2% 34.4%
1.2% 46.1%
0.3% 5.8%
6.2 13.6 0.15* 260.8 131.2 0.36**
4.1%
12.8%
27.1%
41.4%
14.6%
332.2 200.0 0.57**
125 g
25.9%
15.7%
47.5%
8.5%
2.3%
193.1 199.5 0.72**
Never or seldom
<1 per day
1e2 per day
3e4 per day
5 per day
41.4%
22.4%
31.5%
4.4%
0.3%
27.5 48.9
0.38**
0.0%
6.4%
67.9%
22.2%
3.5%
28.9 13.3
0.23**
75.5%
20.7%
3.87%
0.0%
0.0%
3.0 3.8
0.34**
42.9%
27.1%
23.0%
5.8%
1.2%
120.9 159.4 0.84**
Never or seldom
<1 per week
1e3 per week
4e6 per week
7 per week
14.9%
23.0%
51.6%
9.3%
1.2%
77.8 52.4
0.53**
6.1%
27.1%
60.6%
5.8%
0.3%
46.9 47.1
0.44**
200 ml (1 glass) 74.9%
13.7%
7.3%
1.7%
2.3%
42.5 123.7 0.65**
100 g
30.0%
27.7%
27.7%
10.5%
4.1%
52.4 58.3
0.49**
Never or seldom
<1 per week
1 per week
2e3 per week
4 per week
9.0%
18.1%
36.4%
33.5%
2.9%
45.3 33.4
0.62**
31.8%
24.5%
15.2%
18.1%
10.5%
14.5 18.5
0.62**
11.4%
26.2%
35.6%
22.4%
4.4%
16.4 14.8
0.63**
50 g (1e2 slices) 10 ml (1 spoon) 10 g (1 spoon) 125 ml (1 glass)
100 g (raw meat) 50 g (meat products) 100 g
150 g (fish) 50 g (fish products) 30 g (1 fist) 50 g (dried) 150 g (canned/raw)
Spearman correlation coefficient
Abbreviations: SD, Standard deviation. *p Z 0.005; **p < 0.0001.
Statistical analyses For each of the 15 food items included in the QueMD, we used the Spearman coefficient to assess the correlation between the daily food intakes estimated from the EPICFFQ and the ranking frequency of consumption (1e5) reported in the QueMD. We also prepared box and whiskers plots showing the food intake distribution assessed from the EPIC-FFQ for each intake category of the QueMD. We used the Kappa statistic, with 95% confidence intervals (CIs), to quantify the agreement between the EPIC-FFQ and QueMD for the assignment of each of the 9 points contributing to the aMED score and provided the percentage of agreement between the two instruments for each of its components. Finally, we used intraclass
correlation coefficient (ICC), with 95% CIs, to quantify the agreement between the aMED score evaluated from the EPIC-FFQ and the QueMD. All analyses were performed with the SAS software version 9.4 (Cary, NC).
Results Seventy four (15.3%) of the 483 invited subjects declined to participate to the study and 66 (13.7%) returned incomplete questionnaires and were therefore excluded. Complete dietary data were available for the remaining 343 individuals (participation rates 71.0%). Characteristics of the participants are presented in Table 1. One hundred and thirty three (38.8%) were enrolled during lung cancer screening, 108 (31.5%) breast
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
Validation of a questionnaire to record Adherence to the Mediterranean Diet
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Table 3 Agreement between the QueMD and EPIC-FFQ for the allocation of points to the nine components of the alternate Mediterranean (aMED) score. Food Items
Wholegrain Productsa Vegetables
Pulses
Fruits
Dried fruits
Red meat and meat product Fish
Olive oil
Wine
a b
Gender
Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All
Criteria for 1 point
EPIC-FFQ/QueMD
FFQ Daily intakeb
QueMD Frequency
0/0
0/1
1/0
1/1
>12.0 g >20.1 g
1/day
>229.4 g >239.6 g
2/day
>14.1 g >12.2 g
2/week
>282.3 g >311.3 g
2/day
>6.5 g >5.3 g
2/week
<78.8 g <62.6 g
3/week
>37.4 g >37.6 g
2/week
>30.3 g >26.1 g
3/day
125e250 ml 62.5e125 ml
1e2/day >0 < 1/day
34 81 115 49 58 107 52 102 154 47 64 111 55 102 157 12 20 32 50 95 145 48 94 142 68 147 215
25 32 57 10 55 65 6 11 17 12 49 61 4 12 16 47 93 140 8 18 26 10 19 29 12 34 46
30 54 84 32 26 58 33 64 97 12 28 40 31 57 88 1 3 4 28 45 73 41 72 113 19 22 41
28 59 87 26 87 113 26 49 75 46 85 131 27 55 82 57 110 167 31 68 99 18 41 59 18 23 41
Percent of agreement
Kappa (95% CI)
53.0% 61.9% 58.9% 64.1% 64.2% 64.1% 66.7% 66.8% 66.8% 79.5% 65.9% 70.6% 70.1% 69.5% 69.7% 59.0% 57.5% 58.0% 69.2% 72.1% 71.1% 56.4% 59.7% 58.6% 73.5% 75.2% 74.6%
0.06 0.24 0.18 0.28 0.28 0.28 0.34 0.34 0.34 0.59 0.32 0.41 0.40 0.39 0.39 0.18 0.15 0.16 0.39 0.44 0.42 0.13 0.19 0.17 0.35 0.29 0.32
(0.00e0.24) (0.11e0.36) (0.07e0.28) (0.12e0.44) (0.16e0.40) (0.18e0.38) (0.18e0.49) (0.23e0.44) (0.25e0.42) (0.44e0.74) (0.20e0.44) (0.32e0.51) (0.25e0.55) (0.28e0.50) (0.30e0.48) (0.07e0.30) (0.07e0.23) (0.10e0.23) (0.23e0.54) (0.33e0.56) (0.33e0.52) (0.00e0.28) (0.08e0.31) (0.08e0.26) (0.17e0.54) (0.15e0.44) (0.20e0.43)
Obtained from the combination of questions 1 and 5 “wholegrain pasta or rice” and “wholegrain bread and substitutes” in the QueMD. Based on the sex-specific median daily consumption reported among study participants.
cancer screening, and 102 (29.7%) dermatological control. Majority of participants were women (n Z 226, 65.9%); their mean age was 57.6 10.5 years and their mean body mass index (BMI) calculated from self-reported measurements was 24.2 3.8 kg/m2. Overall, the majority of subjects in the dermatological control and breast cancer screening groups referred a normal weight (73.5% and 70.4% respectively), while majority of subjects in the lung cancer screening group were either overweight or obese (54.9%). Correlation between the consumption frequencies for the 15 questions of the QueMD and the daily consumption of the corresponding food items assessed from the EPICFFQ are presented in Table 2 and Supplemental Fig. 1a and b. The correlation was poor for the intake of wholegrain pasta and rice (spearman correlation coefficient r Z 0.15) and for olive oil (r Z 0.23), moderate for butter and margarine (r Z 0.34), vegetables (r Z 0.36), wholegrain bread and substitutes (r Z 0.38), white meat (r Z 0.44) and manufactured sweets, pastries & biscuits (r Z 0.49), high for red meat (r Z 0.53), fresh fruits (r Z 0.57), fish (r Z 0.62), dried fruits (r Z 0.62), pulses (r Z 0.63), soft drinks (r Z 0.65), milk and yoghurt (r Z 0.72), and highest for wine consumption (r Z 0.84). Results were similar in males and in females (Supplemental Table 2). The agreement between the QueMD and the EPIC-FFQ for the assignment of points to the nine items part of the
aMED score, are reported in Table 3. The percent of agreement between the two instruments was comprised between 53.0% for wholegrain products and 79.5% for fresh fruits, with little variation between genders. The Kappa statistic demonstrated only poor agreement (kappa values comprised between 0 and 0.20) for wholegrain
Figure 1 Correlation between the aMED scores evaluated from the QueMD and EPIC-FFQ. Abbreviation: ICC, Intraclass Correlation Coefficient.
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
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products, red meat and olive oil, fair agreement (kappa 0.21e0.40) for vegetables, pulses, dried fruits, and wine, and moderate agreement (kappa 0.41e0.60) for fresh fruits and fish. Results were similar when we changed the cut-off values for the assignments of points in the EPIC-FFQ, substituting median values reported in all participants in our study by National mean daily consumptions [28,29] (Supplemental Table 3). Fig. 1 shows the correlation between the aMED score (with values ranging from 0 to 9) obtained from the QueMD and the EPIC-FFQ. The ICC was 0.50 (95% CI, 0.42e0.58), similar in men ICC Z 0.51 (0.37e0.63) and in women ICC Z 0.49 (0.39e0.59). Supplemental Tables 4 and 5 present the daily nutrients intake, total energy intake, and daily consumption of main food groups derived from the EPIC-FFQ to provide a broad description of the diet in our study population. For both genders combined, the mean energy intake was 2359 kcal (9923 kJ) per day. Protein contributed on average to 15% of total food energy, fat to 35%, carbohydrates to 46% and alcohol to 4%. We observed a higher intake of total fat, total saturated fatty acids (FSA) (11% of total calories), cholesterol (325 mg/day), soluble carbohydrates (20% of total calories) and a low intake of dietary fiber (20 g/day), compared to the national recommendations [20]. Discussion The present study aimed to validate a self-administered short questionnaire (QueMD) for the assessment of the adherence to Mediterranean diet in an Italian population. This is the first short Italian questionnaire to assess adherence to the Mediterranean diet, being validated against an established FFQ. It is a fast and simple tool, which could easily be either self- or in-person administered, and perform reasonably well for the assessment of a number of foods, including those characterizing the Mediterranean diet. It is particularly adapted for epidemiological studies in situations in which the use of longer questionnaires is not feasible, but it should not be used for evaluating dietary adequacy of responders. The need of short dietary instrument has been increasingly recognized [9,11,14,30] and in specific setting, short FFQs perform as well as full questionnaires [31]. Replacement of long questionnaires by shorter versions has also been shown to be appropriate for clinical and research purposes in many other areas [32,33] and is associated with higher response rates [34]. We found a moderate correlation between the aMED score obtained from the QueMD and reference EPIC-FFQ (ICC Z 0.50, 95% CI, 0.42e0.58). This result is in line with those obtained from other validations studies. SotosPrieto et al. [35] reported an overall correlation of r Z 0.63 of a 28-item questionnaire tested against a FFQ developed for the Spanish population. Similar results (ICC of r Z 0.52 in men and in women) were obtained for the 14-point MEDAS questionnaire developed for the PREDIMED study [11].
P. Gnagnarella et al.
The agreement between the single items of the aMED score ranged from 53.0% to 79.5% (Table 3), being poor to fair for 7 of the 9 food items composing the Mediterranean diet. This variation could largely be ascribed to differences in the instruments, with single specific targeted questions in the QueMD versus comprehensive food assessment in the FFQ. For instance, the frequency of “red meat and meat products” in the QueMD was compared with the aggregation of more than 30 questions inquiring single type of raw meat and meat products in two different sections (EPIC-FFQ), resulting in a poor agreement (all gender 58.0%) between the two instruments. A poor agreement (all gender 58.9%) was also found for wholegrain cereal products, mainly because consumption of wholegrain pasta or rice is not specifically addressed in the EPIC-FFQ, which was designed in the late 90s. Poor agreement was also observed for olive oil (all gender 58.6%), probably because olive oil consumption in the FFQ is derived from many questions (including recipes, cooking and seasoning), which could have led to an overestimation, compared to the single question in the QueMD. On the contrary, a moderate agreement was found for fruits and fish (all gender 70.6% and 71.1% respectively), probably because the consumption of this food are generally more regular and simple to remember. The assignment of points to the aMED score is based on low or high food consumption levels established by the median consumption reported in the study population [2,24,25]. This approach is valid for national population-based studies and large-scale cohort studies. Our population was however selected among participants to cancer-screening programmes and may not be representative of the general population, being more attentive to general prevention recommendations in the breast and skin cancer screening groups, or less attentive in the lung cancer screening group which is restricted to heavy smokers. Using median intakes in our series to define the cut-offs for the definition of the aMED score may have introduced a bias. Therefore, we performed an alternative evaluation using published National mean daily food consumptions [28,29], but the results were similar (Supplemental Table 3). Similarly, we based assignment of points in the QueMD on general recommendations [26], but the limited number of available categories (5 levels from “never or seldom” to high frequency) and common response to food item such as olive oil, for which 67.9% of participants reported a typical consumption of “once per day”, may again have introduced some bias. We also evaluated the correlations between the 15 items of the QueMD and the corresponding food items assessed from the EPIC-FFQ (Table 2). The correlation coefficient for the 9 items included in the aMED score are aligned with the kappa statistic, but it is interesting to note that the remaining items (milk and yogurt, butter, white meat, carbonated and/or sugar-sweetened beverages and sweets) present good correlations. These items could be used with the other items to build a global score for the QueMD. This study presents the validation of an original short tool to measure the Mediterranean diet in the Italian population. Such instrument is lacking as often researchers
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
Validation of a questionnaire to record Adherence to the Mediterranean Diet
use the translation of questionnaires developed and validated in other countries to measure the adherence to the Mediterranean diet [36,37]. A similar validation study from Italy has been recently published [14] using, as reference, another short instrument to measure the Mediterranean diet validated in Greece [15]. The two scores presented an overall good correlation (r Z 0.70), but this was expected as they were both specifically developed to measure the same dietary pattern. They contain similar questions (nine in the MEDI-LITE vs eleven in the MDS) about the consumption of food items typical of the Mediterranean diet. The validation was made between the two short instruments, without a real gold standard for measuring dietary intake. Validation studies usually test new instruments against FFQ [9,13,35] or multiple 24h-recalls [11], which are considered superior standard methods [38] recording consumption of a wider list of foods. Use of a FFQ as reference method can however represent a limitation as this tool is not error-free, unlike other instruments usually used as gold-standard in nutritional epidemiology [39]. However, FFQ gives a good surrogate of the true diet providing detailed information about habitual dietary intake in term of nutrients, single food and food groups. A potential limitation is the representativeness of our study sample, as subjects were enrolled among participants to cancer screening programme in a private comprehensive cancer center. This selected group is likely to have higher socioeconomic status, and different nutritional behavior than the general population. Moreover, the sample was unbalanced, with more women than men, due to the enrollment of participants to breast cancer screening. In addition, majority (82.5%) of the participants were over age 50, as breast and lung cancer screening programmes are recommended after age 50 in Italy. Finally, those enrolled in the lung cancer screening programme were all heavy smokers. Despite these limitations, consumption of food and nutrients assessed by the EPIC-FFQ were in line with levels reported in the last National Food Consumption Survey (INRAN-SCAI 2005) [28,40]. Finally, we were not able to correlate the aMED score obtained from the QueMD questionnaires with serological biomarkers or other clinical characteristics that could be associated with the Mediterranean diet, such as hypertension, diabetes, obesity and hypercholesterolemia [15,41]. We foresee to confirm the validity of our QueMD in the near future. In conclusion, this short self-administered questionnaire is a reasonable tool for the rapid assessment of adherence to Mediterranean diet. It can reduce the total costs and data collection in large epidemiological studies, but it could also be useful in time-limited setting, helping dietitians to monitor dietary pattern over time and to give immediate feedback to participants. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors.
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Conflicts of interest None. Acknowledgements We thank William Russel-Edu for help with the literature. Appendix A. Supplementary data Supplementary data related to this article can be found at https://doi.org/10.1016/j.numecd.2018.06.006. References [1] Dinu M, Pagliai G, Casini A, Sofi F. Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomised trials. Eur J Clin Nutr 2018;72: 30e43. [2] Schwingshackl L, Hoffmann G. Adherence to Mediterranean diet and risk of cancer: a systematic review and meta-analysis of observational studies. Int J Cancer 2014;135:1884e97. [3] Bach A, Serra-Majem L, Carrasco JL, Roman B, Ngo J, Bertomeu I, et al. The use of indexes evaluating the adherence to the mediterranean diet in epidemiological studies: a review. Publ Health Nutr 2006;9:132e46. [4] England CY, Andrews RC, Jago R, Thompson JL. A systematic review of brief dietary questionnaires suitable for clinical use in the prevention and management of obesity, cardiovascular disease and type 2 diabetes. Eur J Clin Nutr 2015;69:977e1003. [5] Schulze MB, Hoffmann K. Methodological approaches to study dietary patterns in relation to risk of coronary heart disease and stroke. Br J Nutr 2006;95:860e9. [6] Kourlaba G, Panagiotakos DB. Dietary quality indices and human health: a review. Maturitas 2009;62:1e8. [7] Wirt A, Collins CE. Diet qualityewhat is it and does it matter? Publ Health Nutr 2009;12:2473e92. [8] Martinez-Gonzalez MA, Bes-Rastrollo M, Serra-Majem L, Lairon D, Estruch R, Trichopoulou A. Mediterranean food pattern and the primary prevention of chronic disease: recent developments. Nutr Rev 2009;67(Suppl 1):S111e6. [9] Martínez-González MA, Fernández-Jarne E, Serrano-Martínez M, Wright M, Gomez-Gracia E. Development of a short dietary intake questionnaire for the quantitative estimation of adherence to a cardioprotective Mediterranean diet. Eur J Clin Nutr 2004;58: 1550e2. [10] Rumawas ME, Dwyer JT, McKeown NM, Meigs JB, Rogers G, Jacques PF. The development of the Mediterranean-style dietary pattern score and its application to the American diet in the Framingham Offspring Cohort. J Nutr 2009;139:1150e6. [11] Schröder H, Fitó M, Estruch R, Martínez-González MA, Corella D, Salas-Salvadó J, et al. A short screener is valid for assessing Mediterranean diet adherence among older Spanish men and women. J Nutr 2011;141:1140e5. [12] Athanasiadou E, Kyrkou C, Fotiou M, Tsakoumaki F, Dimitropoulou A, Polychroniadou E, et al. Development and validation of a mediterranean oriented culture-specific semi-quantitative food frequency questionnaire. Nutrients 2016;8(9). [13] Hebestreit K, Yahiaoui-Doktor M, Engel C, Vetter W, Siniatchkin M, Erickson N, et al. Validation of the German version of the mediterranean diet adherence screener (MEDAS) questionnaire. BMC Cancer. 2017;17:341. [14] Sofi F, Dinu M, Pagliai G, Marcucci R, Casini A. Validation of a literature-based adherence score to Mediterranean diet: the MEDI-LITE score. Int J Food Sci Nutr 2017;68:757e62. [15] Panagiotakos DB, Pitsavos C, Arvaniti F, Stefanadis C. Adherence to the Mediterranean food pattern predicts the prevalence of hypertension, hypercholesterolemia, diabetes and obesity, among healthy adults; the accuracy of the MedDietScore. Prev Med 2007; 44:335e40.
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8 [16] Gnagnarella P, Maisonneuve P, Bellomi M, Rampinelli C, Bertolotti R, Spaggiari L, et al. Red meat, Mediterranean diet and lung cancer risk among heavy smokers in the COSMOS screening study. Ann Oncol 2013;24:2606e11. [17] Naska A, Trichopoulou A. Back to the future: the Mediterranean diet paradigm. Nutr Metabol Cardiovasc Dis 2014;24:216e9. [18] World Cancer Research Fund International/American Institute for Cancer Research. Continuous update project report: diet, nutrition, physical activity and colorectal cancer. 2017. [19] World Cancer Research Fund International/American Institute for Cancer Research. Continuous update project report: diet, nutrition, physical activity and prostate cancer. 2014. [20] LARN. IV Revisione dei Livelli di Assunzione di Riferimento di Nutrienti ed energia per la popolazione italiana. Società Italiana di Nutrizione Umana (SINU); 2014. [21] Pisani P, Faggiano F, Krogh V, Palli D, Vineis P, Berrino F. Relative validity and reproducibility of a food frequency dietary questionnaire for use in the Italian EPIC centres. Int J Epidemiol 1997; 26(Suppl 1):S152e60. [22] Pala V, Sieri S, Palli D, Salvini S, Berrino F, Bellegotti M, et al. Diet in the Italian EPIC cohorts: presentation of data and methodological issues. Tumori 2003;89:594e607. [23] Gnagnarella P, Parpinel M, Salvini S, Franceschi S, Palli D, Boyle P. The update of the Italian food composition database. J Food Compos Anal 2004;17:509e22. [24] Trichopoulou A, Kouris-Blazos A, Wahlqvist ML, Gnardellis C, Lagiou P, Polychronopoulos E, et al. Diet and overall survival in elderly people. BMJ 1995;311:1457e60. [25] Hoffman R, Gerber M. Evaluating and adapting the Mediterranean diet for non-Mediterranean populations: a critical appraisal. Nutr Rev 2013;71:573e84. [26] AAVV. Gruppo di esperti costituito presso l’Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione (INRAN). Linee guida per una sana alimentazione italiana. Ministero delle Politiche Agricole e Forestali e INRAN. 2003. [27] Bach-Faig A, Berry EM, Lairon D, Reguant J, Trichopoulou A, Dernini S, et al. Mediterranean Diet Foundation Expert Group. Mediterranean diet pyramid today. Science and cultural updates. Publ Health Nutr 2011;14:2274e84. [28] Leclercq C, Arcella D, Piccinelli R, Sette S, Le Donne C, Turrini A. INRAN-scai 2005-06 study group. The Italian national food consumption survey INRAN-SCAI 2005-06: main results in terms of food consumption. Publ Health Nutr 2009;12:2504e32.
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Nutrition, Metabolism & Cardiovascular Diseases journal homepage: www.elsevier.com/locate/nmcd
Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience P. Gnagnarella a,*, D. Dragà a, A.M. Misotti b, S. Sieri c, L. Spaggiari d,e, E. Cassano f, F. Baldini g, L. Soldati h, P. Maisonneuve a a
Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy UOSD Dietologia e Nutrizione Clinica, ASST Melegnano e Martesana, Italy c Department of Research, Epidemiology and Prevention Unit, Fondazione IRCSS Istituto Nazionale dei Tumori, Milan, Italy d Department of Thoracic Surgery, European Institute of Oncology, Milan, Italy e Department of Oncology and Emato-Oncology, University of Milan, Milan, Italy f Breast Imaging Division, European Institute of Oncology, Milan, Italy g Division of Melanoma, Sarcoma and Rare Cancer, European Institute of Oncology, Milan, Italy h Department of Health Sciences, University of Milan, Milan, Italy b
Received 12 March 2018; received in revised form 11 June 2018; accepted 11 June 2018 Handling Editor: A. Siani Available online - - -
KEYWORDS Mediterranean diet; Validation study; Questionnaire
Abstract Background and aims: A greater adherence to the Mediterranean diet has been associated with a reduced risk of major chronic diseases and cancer. The aim of the study was to assess the validity of a new short self-administered 15-item questionnaire (QueMD) to measure adherence to the Mediterranean diet in Italy. Methods and results: Four-hundred and eighty three participants to cancer-screening programmes at the European Institute of Oncology, Milan (Italy) were invited to join this study. Those interested compiled the QueMD and a validated Food Frequency Questionnaire (FFQ) reporting their usual food consumption during the previous six months. We derived the alternate Mediterranean score (aMED) from both questionnaires with values ranging from 0 (minimal adherence) to 9 (maximal adherence). Complete dietary data were available for 343 individuals (participation rates 71.0%). Spearman correlation coefficient between the responses to the 15 questions of the QueMD and corresponding food intake derived from the FFQ ranged from 0.15 to 0.84. A moderate correlation was found between the aMED scores calculated from the QueMD and the FFQ (intraclass correlation coefficient 0.50; 95% CI, 0.42e0.58), while agreement between the two instruments was only poor to fair for 7 of the 9 single items composing the aMED score, with values ranging from 53.0% for wholegrain products to 79.5% for fruits. Conclusion: This new self-administered 15-item questionnaire could be a useful tool to assess adherence to the Mediterranean diet in the Italian population. ª 2018 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.
* Corresponding author. Divisione di Epidemiologia e Biostatistica, Istituto Europeo di Oncologia, Via Ripamonti 435, 20141 Milan, Italy. E-mail address: [email protected] (P. Gnagnarella). https://doi.org/10.1016/j.numecd.2018.06.006 0939-4753/ª 2018 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
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P. Gnagnarella et al.
Introduction The Mediterranean diet represents a healthy dietary pattern indicated for the prevention of non-communicable diseases, being associated with better general health status and longer lifespan [1,2]. It has been acknowledged as an Intangible Cultural Heritage of Humanity by UNESCO in 2013 (https://ich.unesco.org/en/RL/mediterranean-diet00884), and is defined as a dietary pattern common in countries around the Mediterranean basin, rich in foods of vegetable origin (cereals, fruits, vegetables, legumes, nuts, seeds), with olive oil as the principal source of fat, with moderate consumption of fish and seafood, eggs, poultry and dairy products, alcohol (mainly wine) and low consumption of red meat and meat product [3]. In addition to the evaluation of food patterns by means of factorial analysis, principal component analysis or cluster analysis (a posteriori method), more recently, many indexes or scores to measure the adherence to Mediterranean diet have been developed [4]. They attempt to evaluate the overall quality of the diet based on a pattern defined a priori [5]. They combine and weight foods and/or nutrients consumption, converting them into a single score that describes people’s health diet [6,7]. A single method to measure adherence to Mediterranean diet does not exist, mainly because its definition is not universal, being influenced by socio-cultural, religious and economic factors [3]. Differences between the various Mediterranean diet scores proposed are mainly determined by the selection of the variables or components and the different cutoff points or scoring algorithms adopted [8]. However, the use of food frequency questionnaires (FFQs) is strongly recommended to evaluate with accuracy food pattern and quality of diet. FFQs collect information on consumption frequencies and portion size for a broad list of foods and beverages, typically including from 80 to
200 food items, to assess the total diet. These instruments are very useful to determine the dietary intake in term of single nutrients, single foods and food groups, but they are time-consuming, requiring complex data management and processing, and consequently are usually expensive and unsuitable for experimental or observational studies [9]. In time-limited settings, such as intervention or epidemiological studies, alternative instruments for a rapid assessment of the diet are needed. In the context of the 7th examination of the Framingham Offspring Cohort, Rumawas et al. proposed the Mediterranean-Style Dietary Pattern Score (MSDPS) for characterizing dietary patterns, following the principles of the Mediterranean diet [10]. More recently, a Mediterranean Diet Adherence Screener was developed and validated for the PREDIMED study, a multicenter clinical trial aimed to assess the effect of the traditional Mediterranean diet for the prevention of cardiovascular disease in a Spanish population [11]. Short questionnaires have also been recently proposed and validated in other countries [12,13]. To our knowledge, only one short questionnaire to measure adherence to the Mediterranean diet has been developed in Italy [14]. However, this 9-item literaturebased instrument, administered by trained personnel, has only been validated against another short 11-item diet score developed in Greece [15], limiting the overall value of the validation. In the context of the COSMOS study (Continuous Observation of Smoking Subjects), a screening programme for the early diagnosis of lung cancer in high-risk population, we previously studied the association between dietary intake and lung cancer risk using a FFQ. We found that high adherence to Mediterranean diet was associated with a reduced risk of lung cancer [16]. This finding reinforces the importance of this dietary pattern for the prevention of forms of cancer for which the evidence is
Table 1 Characteristics of the participants in the cancer screening groups.
Total Gender Men Women Age (years) Mean SD <50 50-59 60-69 70þ BMI (kg/m2) Mean SD Underweight Normal weight Overweight Obese
All N (%)
Lung cancer screening N (%)
Dermatological control N (%)
Breast cancer screening N (%)
343 (100)
133 (100)
102 (100)
108 (100)
117 (34.1) 226 (65.9)
82 (61.7) 51 (38.3)
35 (34.3) 67 (65.7)
e 108 (100)
57.6 10.5 60 (17.5) 115 (33.5) 136 (39.7) 32 (9.3)
63.9 4.6 e 29 (21.8) 88 (66.2) 16 (12.0)
48.7 12.5 57 (55.9) 21 (20.6) 19 (18.6) 5 (4.9)
58.4 7.1 3 (2.8) 65 (60.2) 29 (26.9) 11 (10.2)
24.2 3.8 6 (1.7) 210 (61.2) 102 (29.7) 25 (7.3)
25.8 3.8 1 (0.8) 59 (44.4) 54 (40.6) 19 (14.3)
22.9 3.2 2 (2.0) 75 (73.5) 22 (21.6) 3 (2.9)
23.5 3.6 3 (2.8) 76 (70.4) 26 (24.1) 3 (2.8)
Abbreviations: SD, Standard deviation; BMI, Body mass index.
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
Validation of a questionnaire to record Adherence to the Mediterranean Diet
still weak. As traditional diet in Mediterranean countries is also changing [17], short validated questionnaires for rapid and repeated assessments of the Mediterranean diet are needed. Therefore, the aim of this study was to validate of a new short self-administered questionnaire to measure adherence to Mediterranean diet in the Italian population. Methods Study population For this validation study, we approached 483 consecutive healthy participants to cancer-screening programmes (mammography for breast cancer, low-dose computed tomography for lung cancer and dermatological check-up for skin cancer) at the European Institute of Oncology (IEO) in Milan, Italy, between May 2014 and June 2015 (Table 1). Subjects were invited to participate to the study during their screening visit. Those interested received an informed consent form and the study questionnaires with the instruction to report their usual diet in the past six months. Only those who signed the consent form and returned the study questionnaires compiled were included in the study. Ethical approval was obtained from the Ethics Committee of the IEO (R53/ 14eIEO 60). Questionnaire to measure Mediterranean diet (QueMD) We developed a self-administered 15-item questionnaire to measure the adherence to Mediterranean diet (QueMD). We included questions for the nine food items usually considered as key components of the Mediterranean diet (wholegrain cereals, raw or cooked vegetables, legumes, fresh fruits, dried fruits, red or processed meat, fish, wine and olive oil), using two separate questions to assess the consumption of wholegrain cereals (wholegrain pasta or rice and wholegrain bread and substitutes). We included additional items, such as the consumption of white meat (chicken, turkey, and rabbit). We decided to explore the consumption of dairy products, focusing only on milk and yogurt (excluding cheese), due to the different portion size of these items and the contrasting effect of different dairy products on cancer risk (i.e., protective for colon, risk for prostate) [18,19]. Finally we included questions for three additional food groups that are not typical of the Mediterranean diet: carbonated and/or sugar sweetened beverages (soft drinks); butter, margarine or cooking cream; and manufactured sweets, pastries and cakes. For each of the 15 food items, responders can choose between five consumption levels ranging from “never or seldom” to a high frequency. The food items were ordered according to their consumption frequency: daily for wholegrain cereals, vegetables, fruits, dairy products, olive oil, butter and wine, or weekly for red and white meat, soft drinks, sweets, fish, dried fruit and pulses. For each question, a standard portion [20] was indicated to help
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reporting consumption as correctly as possible. The questionnaire is available in Supplemental Table 1. EPIC food frequency questionnaire Participants also completed a validated FFQ [21]. This questionnaire developed for the European Prospective Investigation into Cancer and Nutrition (EPIC) study has been regularly used as reference method for estimating the habitual diet in terms of foods and nutrients. It contains 248 questions about 188 different food items, covering 14 sections representing the different courses of a meal. Responders should indicate how many times they consume a given food item (per day, week, month or year) and choose between a selection of images or predefined standard portions, to indicate the food quantity. An ad-hoc software converts collected data into average daily intakes of foods, energy and nutrients [22]. Conversion from foods to nutrients is based on the Italian food composition database that was specifically developed for epidemiological studies [23]. Scoring system for the alternate Mediterranean diet (aMED) in the QueMD and EPIC-FFQ We calculated the aMED score ranging from 0 (minimal adherence to Mediterranean diet) to 9 (maximal adherence) from both questionnaires (QueMD and EPIC-FFQ) following the method proposed by Trichopoulou et al. [24] and successively modified [2,25]. The aMED score from the short QueMD was calculated assigning 1 point to participants reporting consumptions above the average Italian National levels [26] for each of the following foods that are characteristic of the Mediterranean diet [27]: vegetables (2/day), fresh fruits (2/ day), dried fruits (2/week), wholegrain cereals (1/day), pulses (2/week), fish (2/week) and olive oil intakes (3/day). We also assigned 1 point to those consuming red and processed meat 1e3/week and 1 point for men drinking 1e2 glasses of wine per day or women drinking limited amount of wine (>0 < 1/day) (Table 3). The aMED score from the EPIC-FFQ was calculated adding 1 point if the consumption of selected foods was above or below the sex-specific median value of consumption reported by all study participants; vegetables (M > 229.4 g; F > 239.6 g), fruits (M > 282.3 g; F > 311.3 g), nuts (M > 6.5 g; F > 5.3 g), wholegrain cereals (M > 12.0 g; F > 20.1 g), pulses (M > 14.1 g; F > 12.2 g), fish (M > 37.4 g; F > 37.6 g) or olive oil (M > 30.3 g; F > 26.1 g), red and processed meat (M < 7.8 g; F < 62.6 g); finally 1 point was given if wine consumption was comprised between 125 and 250 ml (corresponding to 1e2 glasses/day) for men or between 62.5 and 125 ml (corresponding to 1/2-1 glass/day) for women (Table 3). An alternative score was constructed using mean daily consumptions reported in a large National Italian Survey (IRAN-SCAI 2005e2006) [28,29] instead of the median consumption reported in our study (Supplementary Table 3).
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
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Table 2 Spearman correlation between responses to the 15 items included in the QueMD and corresponding daily consumption recorded by the EPIC-FFQ. Food Items
1. Wholegrain pasta or rice 2. Vegetables, all type (raw and cooked) 3. Fruits, all types fresh and fresh juices 4. Milk and yoghurt
5. Wholegrain bread and substitutes 6. Olive oil to cook and to dress 7. Butter, margarine or cooking cream 8. Wine (white and red)
9. Red meat (beef, veal, pork), meat products
10. White meat (chicken, turkey, rabbit) 11. Carbonated and/or sugarsweetened beverages 12. Manufactured sweets, pastries, biscuits, creams.
13. Fish (fresh or frozen) or sea foods 14. Dried fruits (nuts, almonds, hazelnuts) 15. Pulses (chickpeas, lentils, peas, beans)
QueMD (Frequency of consumption) Reference portions
Never or seldom
<1 per day
1 per day 2 per day 3 per day
EPIC-FFQ (g/day) Mean SD
80 g 200 g 80 g (salad) 150 g
48.4% 0.6%
30.9% 13.1%
19.2% 34.4%
1.2% 46.1%
0.3% 5.8%
6.2 13.6 0.15* 260.8 131.2 0.36**
4.1%
12.8%
27.1%
41.4%
14.6%
332.2 200.0 0.57**
125 g
25.9%
15.7%
47.5%
8.5%
2.3%
193.1 199.5 0.72**
Never or seldom
<1 per day
1e2 per day
3e4 per day
5 per day
41.4%
22.4%
31.5%
4.4%
0.3%
27.5 48.9
0.38**
0.0%
6.4%
67.9%
22.2%
3.5%
28.9 13.3
0.23**
75.5%
20.7%
3.87%
0.0%
0.0%
3.0 3.8
0.34**
42.9%
27.1%
23.0%
5.8%
1.2%
120.9 159.4 0.84**
Never or seldom
<1 per week
1e3 per week
4e6 per week
7 per week
14.9%
23.0%
51.6%
9.3%
1.2%
77.8 52.4
0.53**
6.1%
27.1%
60.6%
5.8%
0.3%
46.9 47.1
0.44**
200 ml (1 glass) 74.9%
13.7%
7.3%
1.7%
2.3%
42.5 123.7 0.65**
100 g
30.0%
27.7%
27.7%
10.5%
4.1%
52.4 58.3
0.49**
Never or seldom
<1 per week
1 per week
2e3 per week
4 per week
9.0%
18.1%
36.4%
33.5%
2.9%
45.3 33.4
0.62**
31.8%
24.5%
15.2%
18.1%
10.5%
14.5 18.5
0.62**
11.4%
26.2%
35.6%
22.4%
4.4%
16.4 14.8
0.63**
50 g (1e2 slices) 10 ml (1 spoon) 10 g (1 spoon) 125 ml (1 glass)
100 g (raw meat) 50 g (meat products) 100 g
150 g (fish) 50 g (fish products) 30 g (1 fist) 50 g (dried) 150 g (canned/raw)
Spearman correlation coefficient
Abbreviations: SD, Standard deviation. *p Z 0.005; **p < 0.0001.
Statistical analyses For each of the 15 food items included in the QueMD, we used the Spearman coefficient to assess the correlation between the daily food intakes estimated from the EPICFFQ and the ranking frequency of consumption (1e5) reported in the QueMD. We also prepared box and whiskers plots showing the food intake distribution assessed from the EPIC-FFQ for each intake category of the QueMD. We used the Kappa statistic, with 95% confidence intervals (CIs), to quantify the agreement between the EPIC-FFQ and QueMD for the assignment of each of the 9 points contributing to the aMED score and provided the percentage of agreement between the two instruments for each of its components. Finally, we used intraclass
correlation coefficient (ICC), with 95% CIs, to quantify the agreement between the aMED score evaluated from the EPIC-FFQ and the QueMD. All analyses were performed with the SAS software version 9.4 (Cary, NC).
Results Seventy four (15.3%) of the 483 invited subjects declined to participate to the study and 66 (13.7%) returned incomplete questionnaires and were therefore excluded. Complete dietary data were available for the remaining 343 individuals (participation rates 71.0%). Characteristics of the participants are presented in Table 1. One hundred and thirty three (38.8%) were enrolled during lung cancer screening, 108 (31.5%) breast
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
Validation of a questionnaire to record Adherence to the Mediterranean Diet
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Table 3 Agreement between the QueMD and EPIC-FFQ for the allocation of points to the nine components of the alternate Mediterranean (aMED) score. Food Items
Wholegrain Productsa Vegetables
Pulses
Fruits
Dried fruits
Red meat and meat product Fish
Olive oil
Wine
a b
Gender
Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All Men Women All
Criteria for 1 point
EPIC-FFQ/QueMD
FFQ Daily intakeb
QueMD Frequency
0/0
0/1
1/0
1/1
>12.0 g >20.1 g
1/day
>229.4 g >239.6 g
2/day
>14.1 g >12.2 g
2/week
>282.3 g >311.3 g
2/day
>6.5 g >5.3 g
2/week
<78.8 g <62.6 g
3/week
>37.4 g >37.6 g
2/week
>30.3 g >26.1 g
3/day
125e250 ml 62.5e125 ml
1e2/day >0 < 1/day
34 81 115 49 58 107 52 102 154 47 64 111 55 102 157 12 20 32 50 95 145 48 94 142 68 147 215
25 32 57 10 55 65 6 11 17 12 49 61 4 12 16 47 93 140 8 18 26 10 19 29 12 34 46
30 54 84 32 26 58 33 64 97 12 28 40 31 57 88 1 3 4 28 45 73 41 72 113 19 22 41
28 59 87 26 87 113 26 49 75 46 85 131 27 55 82 57 110 167 31 68 99 18 41 59 18 23 41
Percent of agreement
Kappa (95% CI)
53.0% 61.9% 58.9% 64.1% 64.2% 64.1% 66.7% 66.8% 66.8% 79.5% 65.9% 70.6% 70.1% 69.5% 69.7% 59.0% 57.5% 58.0% 69.2% 72.1% 71.1% 56.4% 59.7% 58.6% 73.5% 75.2% 74.6%
0.06 0.24 0.18 0.28 0.28 0.28 0.34 0.34 0.34 0.59 0.32 0.41 0.40 0.39 0.39 0.18 0.15 0.16 0.39 0.44 0.42 0.13 0.19 0.17 0.35 0.29 0.32
(0.00e0.24) (0.11e0.36) (0.07e0.28) (0.12e0.44) (0.16e0.40) (0.18e0.38) (0.18e0.49) (0.23e0.44) (0.25e0.42) (0.44e0.74) (0.20e0.44) (0.32e0.51) (0.25e0.55) (0.28e0.50) (0.30e0.48) (0.07e0.30) (0.07e0.23) (0.10e0.23) (0.23e0.54) (0.33e0.56) (0.33e0.52) (0.00e0.28) (0.08e0.31) (0.08e0.26) (0.17e0.54) (0.15e0.44) (0.20e0.43)
Obtained from the combination of questions 1 and 5 “wholegrain pasta or rice” and “wholegrain bread and substitutes” in the QueMD. Based on the sex-specific median daily consumption reported among study participants.
cancer screening, and 102 (29.7%) dermatological control. Majority of participants were women (n Z 226, 65.9%); their mean age was 57.6 10.5 years and their mean body mass index (BMI) calculated from self-reported measurements was 24.2 3.8 kg/m2. Overall, the majority of subjects in the dermatological control and breast cancer screening groups referred a normal weight (73.5% and 70.4% respectively), while majority of subjects in the lung cancer screening group were either overweight or obese (54.9%). Correlation between the consumption frequencies for the 15 questions of the QueMD and the daily consumption of the corresponding food items assessed from the EPICFFQ are presented in Table 2 and Supplemental Fig. 1a and b. The correlation was poor for the intake of wholegrain pasta and rice (spearman correlation coefficient r Z 0.15) and for olive oil (r Z 0.23), moderate for butter and margarine (r Z 0.34), vegetables (r Z 0.36), wholegrain bread and substitutes (r Z 0.38), white meat (r Z 0.44) and manufactured sweets, pastries & biscuits (r Z 0.49), high for red meat (r Z 0.53), fresh fruits (r Z 0.57), fish (r Z 0.62), dried fruits (r Z 0.62), pulses (r Z 0.63), soft drinks (r Z 0.65), milk and yoghurt (r Z 0.72), and highest for wine consumption (r Z 0.84). Results were similar in males and in females (Supplemental Table 2). The agreement between the QueMD and the EPIC-FFQ for the assignment of points to the nine items part of the
aMED score, are reported in Table 3. The percent of agreement between the two instruments was comprised between 53.0% for wholegrain products and 79.5% for fresh fruits, with little variation between genders. The Kappa statistic demonstrated only poor agreement (kappa values comprised between 0 and 0.20) for wholegrain
Figure 1 Correlation between the aMED scores evaluated from the QueMD and EPIC-FFQ. Abbreviation: ICC, Intraclass Correlation Coefficient.
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
6
products, red meat and olive oil, fair agreement (kappa 0.21e0.40) for vegetables, pulses, dried fruits, and wine, and moderate agreement (kappa 0.41e0.60) for fresh fruits and fish. Results were similar when we changed the cut-off values for the assignments of points in the EPIC-FFQ, substituting median values reported in all participants in our study by National mean daily consumptions [28,29] (Supplemental Table 3). Fig. 1 shows the correlation between the aMED score (with values ranging from 0 to 9) obtained from the QueMD and the EPIC-FFQ. The ICC was 0.50 (95% CI, 0.42e0.58), similar in men ICC Z 0.51 (0.37e0.63) and in women ICC Z 0.49 (0.39e0.59). Supplemental Tables 4 and 5 present the daily nutrients intake, total energy intake, and daily consumption of main food groups derived from the EPIC-FFQ to provide a broad description of the diet in our study population. For both genders combined, the mean energy intake was 2359 kcal (9923 kJ) per day. Protein contributed on average to 15% of total food energy, fat to 35%, carbohydrates to 46% and alcohol to 4%. We observed a higher intake of total fat, total saturated fatty acids (FSA) (11% of total calories), cholesterol (325 mg/day), soluble carbohydrates (20% of total calories) and a low intake of dietary fiber (20 g/day), compared to the national recommendations [20]. Discussion The present study aimed to validate a self-administered short questionnaire (QueMD) for the assessment of the adherence to Mediterranean diet in an Italian population. This is the first short Italian questionnaire to assess adherence to the Mediterranean diet, being validated against an established FFQ. It is a fast and simple tool, which could easily be either self- or in-person administered, and perform reasonably well for the assessment of a number of foods, including those characterizing the Mediterranean diet. It is particularly adapted for epidemiological studies in situations in which the use of longer questionnaires is not feasible, but it should not be used for evaluating dietary adequacy of responders. The need of short dietary instrument has been increasingly recognized [9,11,14,30] and in specific setting, short FFQs perform as well as full questionnaires [31]. Replacement of long questionnaires by shorter versions has also been shown to be appropriate for clinical and research purposes in many other areas [32,33] and is associated with higher response rates [34]. We found a moderate correlation between the aMED score obtained from the QueMD and reference EPIC-FFQ (ICC Z 0.50, 95% CI, 0.42e0.58). This result is in line with those obtained from other validations studies. SotosPrieto et al. [35] reported an overall correlation of r Z 0.63 of a 28-item questionnaire tested against a FFQ developed for the Spanish population. Similar results (ICC of r Z 0.52 in men and in women) were obtained for the 14-point MEDAS questionnaire developed for the PREDIMED study [11].
P. Gnagnarella et al.
The agreement between the single items of the aMED score ranged from 53.0% to 79.5% (Table 3), being poor to fair for 7 of the 9 food items composing the Mediterranean diet. This variation could largely be ascribed to differences in the instruments, with single specific targeted questions in the QueMD versus comprehensive food assessment in the FFQ. For instance, the frequency of “red meat and meat products” in the QueMD was compared with the aggregation of more than 30 questions inquiring single type of raw meat and meat products in two different sections (EPIC-FFQ), resulting in a poor agreement (all gender 58.0%) between the two instruments. A poor agreement (all gender 58.9%) was also found for wholegrain cereal products, mainly because consumption of wholegrain pasta or rice is not specifically addressed in the EPIC-FFQ, which was designed in the late 90s. Poor agreement was also observed for olive oil (all gender 58.6%), probably because olive oil consumption in the FFQ is derived from many questions (including recipes, cooking and seasoning), which could have led to an overestimation, compared to the single question in the QueMD. On the contrary, a moderate agreement was found for fruits and fish (all gender 70.6% and 71.1% respectively), probably because the consumption of this food are generally more regular and simple to remember. The assignment of points to the aMED score is based on low or high food consumption levels established by the median consumption reported in the study population [2,24,25]. This approach is valid for national population-based studies and large-scale cohort studies. Our population was however selected among participants to cancer-screening programmes and may not be representative of the general population, being more attentive to general prevention recommendations in the breast and skin cancer screening groups, or less attentive in the lung cancer screening group which is restricted to heavy smokers. Using median intakes in our series to define the cut-offs for the definition of the aMED score may have introduced a bias. Therefore, we performed an alternative evaluation using published National mean daily food consumptions [28,29], but the results were similar (Supplemental Table 3). Similarly, we based assignment of points in the QueMD on general recommendations [26], but the limited number of available categories (5 levels from “never or seldom” to high frequency) and common response to food item such as olive oil, for which 67.9% of participants reported a typical consumption of “once per day”, may again have introduced some bias. We also evaluated the correlations between the 15 items of the QueMD and the corresponding food items assessed from the EPIC-FFQ (Table 2). The correlation coefficient for the 9 items included in the aMED score are aligned with the kappa statistic, but it is interesting to note that the remaining items (milk and yogurt, butter, white meat, carbonated and/or sugar-sweetened beverages and sweets) present good correlations. These items could be used with the other items to build a global score for the QueMD. This study presents the validation of an original short tool to measure the Mediterranean diet in the Italian population. Such instrument is lacking as often researchers
Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006
Validation of a questionnaire to record Adherence to the Mediterranean Diet
use the translation of questionnaires developed and validated in other countries to measure the adherence to the Mediterranean diet [36,37]. A similar validation study from Italy has been recently published [14] using, as reference, another short instrument to measure the Mediterranean diet validated in Greece [15]. The two scores presented an overall good correlation (r Z 0.70), but this was expected as they were both specifically developed to measure the same dietary pattern. They contain similar questions (nine in the MEDI-LITE vs eleven in the MDS) about the consumption of food items typical of the Mediterranean diet. The validation was made between the two short instruments, without a real gold standard for measuring dietary intake. Validation studies usually test new instruments against FFQ [9,13,35] or multiple 24h-recalls [11], which are considered superior standard methods [38] recording consumption of a wider list of foods. Use of a FFQ as reference method can however represent a limitation as this tool is not error-free, unlike other instruments usually used as gold-standard in nutritional epidemiology [39]. However, FFQ gives a good surrogate of the true diet providing detailed information about habitual dietary intake in term of nutrients, single food and food groups. A potential limitation is the representativeness of our study sample, as subjects were enrolled among participants to cancer screening programme in a private comprehensive cancer center. This selected group is likely to have higher socioeconomic status, and different nutritional behavior than the general population. Moreover, the sample was unbalanced, with more women than men, due to the enrollment of participants to breast cancer screening. In addition, majority (82.5%) of the participants were over age 50, as breast and lung cancer screening programmes are recommended after age 50 in Italy. Finally, those enrolled in the lung cancer screening programme were all heavy smokers. Despite these limitations, consumption of food and nutrients assessed by the EPIC-FFQ were in line with levels reported in the last National Food Consumption Survey (INRAN-SCAI 2005) [28,40]. Finally, we were not able to correlate the aMED score obtained from the QueMD questionnaires with serological biomarkers or other clinical characteristics that could be associated with the Mediterranean diet, such as hypertension, diabetes, obesity and hypercholesterolemia [15,41]. We foresee to confirm the validity of our QueMD in the near future. In conclusion, this short self-administered questionnaire is a reasonable tool for the rapid assessment of adherence to Mediterranean diet. It can reduce the total costs and data collection in large epidemiological studies, but it could also be useful in time-limited setting, helping dietitians to monitor dietary pattern over time and to give immediate feedback to participants. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors.
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Please cite this article in press as: Gnagnarella P, et al., Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience, Nutrition, Metabolism & Cardiovascular Diseases (2018), https://doi.org/10.1016/j.numecd.2018.06.006