Reliability and Validity of the 14-point mediterranean diet adherence screener among the Iranian high risk population
Abstract
INTRODUCTION:
The aim of study was to assess the reliability and validity of the14-point Mediterranean Diet Adherence Screener (MEDAS) among Iranian high risk population.
METHODS:
Study was conducted in north of Iran a country with a Shiite majority with religious constraints, so we modified the MEDAS in the Farsi version. We applied reliability analysis using the Kuder – Richardson 20 and the alpha coefficient of Cronbach, with SPSS to interpret the effects of each item of MEDAS in its internal consistency.
RESULTS:
After correcting the item scores, coefficients of Kuder-Richardson-20 was calculated 0.559. The mean±SD of 13 items MEDAS was 5.73±1.88. None of Corrected Item-Total Correlation coefficients were negative. 43%, 53% and 4% participants had low, medium and high adherence to a Mediterranean diet respectively.
CONCLUSION:
In spite of making a few changes in questions, the coefficients of Kuder-Richardson-20 did not decrease in reliability analysis. The MEDAS was translated for the first time into Farsi. Administering this tool in future researches will help to understand how Iranian adhere to the mediterranean diet, aiming at improving cardiovascular health.
1Introduction
Cardio vascular diseases (CVD) are the most important cause of the burden of diseases globally [1]. Also, CVD is the first reason of death in the Iran because of huge demographic changes and epidemiological transition [2]. Despite, preventive intervention have reduced age adjusted mortality rate of CVD in developed countries [3]. But, neglecting of such programs in developing country cause premature deaths and loss of active years of life [2].
Cardio protective effects of a few specific foods have been established by numerous researches [4]. The Mediterranean dietary pattern consists of daily consumption of non-refined products, vegetables, fruits, olive oil and low-fat dairy products, weekly consumption of potatoes, olives, fish, nuts and poultry and monthly consumption of red meat and meat products. Essential components of the Mediterranean diet are wheat, olives and their various derivative products. Olive oil is the principal source of dietary fat in this pattern [5, 6].
Studies have shown that increasing adherence to the Mediterranean diet is associated with desirable effects on several cardiovascular risk factors [7, 8]. A systematic review and meta-analysis revealed that Mediterranean diet may have beneficial effects respect to CVD. However, the results must be interpreted with caution due to restraint and variety of available evidences [9]. However diet does not act in isolate and multiple risk factors such as socio economic status can effect on CVD [10], but Estimating diet quality and determining its association with health factors is a key challenge in nutrition. and various indices of diet quality have been proposed [11]. In epidemiological studies, food frequency questionnaire (FFQ) is the most used method for estimating an individual’s adherence to a healthy eating pattern. However, the full-length FFQ is time consuming for participants and not an optimal option in busy and crowded settings. A short instrument, capable of correctly estimating adherence to the Mediterranean diet would be useful to control for adherence [12].
A 14-point Mediterranean Diet Adherence Screener (MEDAS) [13] was developed to rapidly control for compliance with the dietary intervention of the Prevencio'n con Dieta Mediterranean (PREDIMED) study, a multicenter clinical trial aimed at assessing the effects of the traditional Mediterranean diet on the primary prevention of cardiovascular disease [12]. This screener can also be used to assess dietary compliance in epidemiological studies [14, 15]. Because of the high prevalence of cardiovascular disease in Iran and cardio protective role of Mediterranean diet, it is necessary to conduct some studies to determine whether the dietary habits of some Iranians, according to their culture, are similar to mediterranean diet or not. To the authors’ knowledge, 14-point Mediterranean diet adherence screener has not been used for assessing dietary compliance in Iranian population. For these reasons, the objective of the present study was to determine reliability and validity of the 14-point Mediterranean diet adherence instrument among the Iranian high risk population participants.
2Methods
The 14-point Mediterranean Diet Adherence Screener (MEDAS) is a valid instrument developed in a study with adult patients under 80 years old who had a definite diagnosis of acute myocardial infarction and were admitted to a tertiary hospital in the Pamplona (Spain) [16]. The MEDAS consist of 12 questions on food consumption frequency and 2 questions about food intake habits based on Spanish Mediterranean diet.
Each question was scored 0 or 1 (Table 1). If a respondent adhered to the condition described in each question, he/she would score one. So the total score of the questionnaire ranged from 0 to 14 [11]. Since we wanted to use MEDAS among the people who were not permitted to drink alcoholic beverages due to their religious beliefs, we deleted question 8 (Do you drink wine? How much do you consume per week?). Also we omitted (ham) from meat products, shellfish and pork in the questions 5, 10 and 13 respectively due to the similar reason expressed for the eighth question. And as this study was conducted in a country with a Shiite majority, then we eliminated the question related to rabbit meat consumption (question number 13) because of religious restrictions; however, this kind of meat is not consumed in Iran overall. Moreover, since custard is not popular in Iran and many of our participants may not be familiar with it, we delete it from the Farsi version of MEDAS. Also, in Iranian cuisine sofrito is not well-known, but every ingredient of this sauce is considered as a popular flavor. So we replaced flavoring such as (tomato, onion, leek, garlic and olive oil) with sofrito. Then we translated, native MEDAS to Persian by backward -forward method and two registered dietitian qualitatively approved the final Persian version content and face validity.
Table 1
The 14-point Mediterranean Diet Adherence Screener (MEDAS)
| Questions | Criteria for 1 point | Corrected Item-Total Correlation | Cronbach’s Alpha if Item Deleted | |
| 1 | Do you use olive oil as main culinary fat? | Yes | 0.357 | 0.482 |
| 2 | How much olive oil do you consume in a given day (including oil used for frying, salads, out-of-house meals, etc.)? | ≥4 tbsp* | 0.365 | 0.475 |
| 3 | How many vegetable servings do you consume per day? (1 serving: 200 g [consider side dishes as half a serving]) | ≥2 (≥1 portion raw or as a salad) | 0.309 | 0.479 |
| 4 | How many fruit units (including natural fruit juices) do you consume per day? | ≥3 | 0.278 | 0.490 |
| 5 | How many servings of red meat, hamburger, or meat products (ham*** , sausage, etc.) do you consume per day? (1 serving: 100–150 g) | <1 | 0.152 | 0.521 |
| 6 | How many servings of butter, margarine, or cream do you consume per day? (1 serving: 12 g) | <1 | 0.159 | 0.519 |
| 7 | How many sweet or carbonated beverages do you drink per day? | <1 | 0.257 | 0.506 |
| 8** | How much wine do you drink per week? | ≥7 glasses | – | – |
| 9 | How many servings of legumes do you consume per week? (1 serving: 150 g) | ≥3 | 0.137 | 0.526 |
| 10 | How many servings of fish or shellfish*** do you consume per week? (1 serving 100–150 g of fish or 4–5 units or 200 g of shellfish) | ≥3 | 0.198 | 0.515 |
| 11 | How many times per week do you consume commercial sweets or pastries (not homemade), such as cakes, cookies, biscuits, or custard*** ? | <3 | 0.054 | 0.557 |
| 12 | How many servings of nuts (including peanuts) do you consume per week? (1 serving 30 g) | ≥3 | 0.200 | 0.513 |
| 13 | Do you preferentially consume chicken, turkey, or rabbit *** meat instead of veal, pork*** , hamburger, or sausage? | Yes | 0.122 | 0.526 |
| 14 | How many times per week do you consume vegetables, pasta, rice, or other dishes seasoned with sofrito† (sauce made with tomato and onion, leek, or garlic and simmered with olive oil)? | ≥2 | 0.198 | 0.517 |
[i] *tbsp(tablespoon ≈15 milliliter). **this item has been deleted from Farsi version. ***This word has been deleted from Farsi version. †this word has been changed in Farsi version.
After getting permission from the research council of Guilan University of Medical Sciences, a registered dietitian fulfilled MEDAS by face to face interview with a convenience sample of 100 patients who were admitted to a tertiary hospital in Rasht (center of Guilan province in the North of Iran) because they were chosen for elective angiography, between June 1 and July 31, 2015. The patients who were diagnosed with renal or inflammatory diseases such as rheumatoid arthritis were excluded from the study. The object of the study was explained to the participants and an oral informed consent was taken from them. Kuder-Richardson 20 formula was used for calculating the internal consistency. As Cronbach’s α is analogous to Kuder-Richardson 20 [17], we applied reliability analysis using model alpha, with SPSS Ver (11.5) to interpret the effects of each item of MEDAS in its internal consistency.
3Results
The interview was presented for 110 participants and 100 of them accepted it (90% response rate). The significant difference between respondents and non-respondents was not detected. 49% of participants were women. Demographic characteristics of the participants are shown in (Table 2). After correcting the item scores, coefficients of Kuder-Richardson-20 was calculated 0.559. Question number 2 (How much olive oil do you consume in a given day (including oil used for frying, salads, out-of-house meals, etc.?) and 11 (How many times per week do you consume commercial sweets or pastries (not homemade), such as cakes, cookies, biscuits, or custard?) had the best and the worst correlation with the rest of items respectively (Table 1). Also, deleting question 11 caused a maximum increase in the value of Cronbach’s alpha (Table 1). The mean (SD) of 13 items MEDAS was 5.73 (1.88). According to three categories of adherence to the Mediterranean diet, (≤5, 6–9 and ≥10 points of the 13-item revised questionnaire) 43 (43%), 53 (53%) and 4 (4%) participants had low, medium and high adherence to a Mediterranean diet respectively. The Table 3 shows the frequency of one point (yes answer) for each item of MEDAS questionnaire according to participants’ responses. Majority of the participants responded “yes” to question 14 (How many times per week do you consume vegetables, pasta, rice, or other dishes seasoned with sofrito (sauce made with tomato and onion, leek, or garlic and simmered with olive oil)?). And most “no” responses were equally given to the questions 7 (How many sweet or carbonated beverages do you drink per day?).
Table 2
Demographic characteristics of the participants
| Characteristics | |
| Age [mean (SD) years] | 58.3 (8.9) |
| Gender [number (%)] | |
| Male | 51 (51.0) |
| Female | 49 (49.0) |
| Educational Level [number (%)] | |
| Illiterate | 37 (37.0) |
| Below diploma | 42 (42.0) |
| Diploma | 18 (18.0) |
| Bachelor and higher | 3 (3.0) |
| Residence Characteristic [number (%)] | |
| Urban | 62 (62.0) |
| Rural | 38 (38.0) |
Table 3
The frequency of yes (1-point) or no (0-point) answers to the 13-point Mediterranean Diet Adherence Screener (ME DAS)according to participants’ responses
| Questions | Yes (1 point) Number (%) | No (0 point) Number (%) | |
| 1 | Do you use olive oil as main culinary fat? | 10 (10.0) | 90 (90.0) |
| 2 | How much olive oil do you consume in a given day (including oil used for frying, salads, out-of-house meals, etc.)? | 13 (13.0) | 87 (87.0) |
| 3 | How many vegetable servings do you consume per day? (1 serving: 200 g [consider side dishes as half a serving]) | 46 (46.0) | 54 (54.0) |
| 4 | How many fruit units (including natural fruit juices) do you consume per day? | 77 (77.0) | 23 (23.0) |
| 5 | How many servings of red meat, hamburger, or meat products (ham*** , sausage, etc.) do you consume per day? (1 serving: 100–150 g) | 13 (13.0) | 87 (87.0) |
| 6 | How many servings of butter, margarine, or cream do you consume per day? (1 serving: 12 g) | 8 (8.0) | 92 (92.0) |
| 7 | How many sweet or carbonated beverages do you drink per day? | 6 (6.0) | 94 (94.0) |
| 8** | How much wine do you drink per week? | – | – |
| 9 | How many servings of legumes do you consume per week? (1 serving: 150 g) | 82 (82.0) | 18 (18.0) |
| 10 | How many servings of fish or shellfish*** do you consume per week? (1 serving 100–150 g of fish or 4–5 units or 200 g of shellfish) | 59 (59.0) | 41 (41.0) |
| 11 | How many times per week do you consume commercial sweets or pastries (not homemade), such as cakes, cookies, biscuits, or custard*** ? | 37 (37.0) | 63 (63.0) |
| 12 | How many servings of nuts (including peanuts) do you consume per week? (1 serving 30 g) | 31 (31.0) | 69 (69.0) |
| 13 | Do you preferentially consume chicken, turkey, or rabbit*** meat instead of veal, pork*** , hamburger, or sausage? | 95 (95.0) | 5 (5.0) |
| 14 | How many times per week do you consume vegetables, pasta, rice, or other dishes seasoned with sofrito† (sauce made with tomato and onion, leek, or garlic and simmered with olive oil)? | 96 (96.0) | 4 (4.0) |
[i] *tbsp.(tablespoon ≈15 milliliter). **this item has been deleted from Farsi version. ***this word has been deleted from Farsi version. †this word has been changed in Farsi version.
4Discussion
In spite of removing question 8 and making a few changes in questions 5, 10, 11, 13 and 14 due to religious reasons, the coefficients of Kuder-Richardson-20 did not decrease by 0.5 or below in reliability analysis. None of Corrected Item-Total Correlation coefficients were negative. The low agreement(0.559) in our study is probably due to homogenous sample of patients, however our result in calculation of internal consistency is very similar to Schroder, H. et al. (ICC = 0.51) [18]. It seems there is a tremendous diversity in the pattern of adherence to Mediterranean diet according to results of MEDAS questionnaire in different regions. As UNESCO (United Nations Educational, Scientific and Cultural Organization) accredited, the Mediterranean diet is not just the specific foods and nutrients, but, a complex of social cultural expression of the different food culture of the Mediterranean [19]. Therefore, it was predictable that the patterns of the consumption of Mediterranean dietary components among our participants were different from those of other peoples and cultures.
Although Iran produces significant amounts of olive [20], the consumption of olive oil compared with other countries in the Mediterranean region is lower in this country. Only 5% of our participants use olive oil as a main culinary fat. And the amount of consumption of this nutrient in 95 percent of our respondents is lower than 60 milliliter (approximately 54 grams) [21] in a given day. While in other countries such as Morocco weekly consumption of olive oil for cooking and dressing was 59.7% up to 89.3% in people with low to high Mediterranean diet adherence respectively [22]. Also in the Framingham offspring cohort 36.9% of participants met the recommended intakes of olive oil [23] and among older Spanish men and women, according to MEDAS screener 90.9 and 70.9 percent used olive oil as the principal source of fat for cooking and consumed 15 milliliter of olive oil or even more [11]. This pattern of high consumption of olive oil (89.9% positive in use of olive oil as main culinary lipid and 70.0 percent positive in >15 milliliter daily olive oil consumption) can be seen in another study with participants at high risk of cardiovascular diseases in Spain [24]. The daily use of olive oil in Greece and Italy is also high like Spain [14, 25]. Regardless of olive oil, we found that the pattern of the Mediterranean diet, according to MEDAS, was different among our participants.
According to MEDAS screener, consumption of legumes, poultry and especially sofrito was more among our participatnts compared with that in other studies [11, 14, 24]. In comparison, the lower use of vegetables and fruits on the one hand, and higher consumption of red/processed meat, butter, cream, margarine and soda drinks on the other hand were the negative points among our participants [11, 14, 24]. Also consumption of dietary components such as fish/seafood, commercial sweets/pastries and tree nuts among our participants was similar to that of others researches [11, 14, 24]. The cause of low Item-Total Correlation in questions can be due to the pattern of the answers to the MEDAS screener in our study. And this phenomenon is related to sociocultural elements that can affect people’s choice of their food and diet. As a limitation of our study we did not evaluate dietery estimate of our participant by a instrumnt such as FFQ (food frequency questionarie), so further study is proposed to evaluate criterion validity of the Persian version of the MEDAS questionnaire.
5Conclusion
In summary, the MEDAS questionnaire was translated into Persian and adjusted according to religious considerations for the first time and its reliability and validity was examined among people who were candidate of elective angiography. This questionnaire screens the adherence to a Mediterranean diet and application of this instrument can help dietician to understand how Iranian adhere to the Mediterranean diet quantitatively and qualitatively. However research on sufficent hetrogenous sample of population highly recommended.
Ethical approval
This paper is the product of a research proposal with the code number of IR. GUMS.REC.1394.184 approved by the research and technology directorate of Guilan University of Medical Sciences.
Competing Interests
Authors declare that they have no competing interests.
References
[1] | Roth GA , Johnson C , Abajobir A , Abd-Allah F , Abera SF , Abyu G , et al. Global, Regional, and national burden of cardiovascular diseases for 10 causes, 1990 to 2015. Journal of the American College of Cardiology. (2017) ;70: (1):1-25. |
[2] | Sadeghi M , Haghdoost AA , Bahrampour A , Dehghani M . Modeling the burden of cardiovascular diseases in Iran from 2005 to 2025: The impact of demographic changes. Iranian Journal of Public Health. (2017) ;46: (4):506-16. |
[3] | Mensah GA , Wei GS , Sorlie PD , Fine LJ , Rosenberg Y , Kaufmann PG , et al. Decline in cardiovascular mortality: Possible causes and implications. Circulation Research. (2017) ;120: (2):366-80. |
[4] | Mozaffarian D , Appel LJ , Van Horn L . Components of a cardioprotective diet. New Insights. (2011) ;123: (24):2870-91. |
[5] | Bach-Faig A , Berry EM , Lairon D , Reguant J , Trichopoulou A , Dernini S , et al. Mediterranean diet pyramid today. Science and cultural updates. Public Health Nutrition. (2011) ;14: (12A):2274-84. |
[6] | Panagiotakos DB , Pitsavos C , Stefanadis C . Dietary patterns: A Mediterranean diet score and its relation to clinical and biological markers of cardiovascular disease risk. Nutrition, Metabolism, and Cardiovascular Diseases: NMCD. (2006) ;16: (8):559-68. |
[7] | Grosso G , Mistretta A , Marventano S , Purrello A , Vitaglione P , Calabrese G , et al. Beneficial effects of the mediterranean diet on metabolic syndrome. Current Pharmaceutical Design. (2014) ;20: (31):5039-44. |
[8] | Grosso G , Pajak A , Mistretta A , Marventano S , Raciti T , Buscemi S , et al. Protective role of the Mediterranean diet on several cardiovascular risk factors: Evidence from Sicily, southern Italy. Nutrition, Metabolism, and Cardiovascular Diseases: NMCD. (2014) ;24: (4):370-7. |
[9] | Liyanage T , Ninomiya T , Wang A , Neal B , Jun M , Wong MG , et al. Effects of the mediterranean diet on cardiovascular outcomes—a systematic review and meta-analysis. PLoS One. (2016) ;11: (8):e0159252. |
[10] | Tchicaya A , Lorentz N , Demarest S , Beissel J . Persistence of socioeconomic inequalities in the knowledge of cardiovascular risk factors five years after coronary angiography. European Journal of Cardiovascular Nursing: Journal of the Working Group on Cardiovascular Nursing of the European Society of Cardiology. (2018) ;17: (2):136-47. |
[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. The Journal of Nutrition. (2011) ;141: (6):1140-5. |
[12] | Hu EA , Toledo E , Diez-Espino J , Estruch R , Corella D , Salas-Salvado J , et al. Lifestyles and risk factors associated with adherence to the Mediterranean diet: A baseline assessment of the PREDIMED trial. PLoS One. (2013) ;8: (4):e60166. |
[13] | Martinez-Gonzalez M , Fernandez-Jarne E , Serrano-Martinez M , Wright M , Gomez-Gracia E . Development of a short dietary intake questionnaire for the quantitative estimation of adherence to a cardioprotective Mediterranean diet. European Journal of Clinical Nutrition. (2004) ;58: (11):1550-2. |
[14] | Barrea L , Balato N , Di Somma C , Macchia P , Napolitano M , Savanelli M , et al. Nutrition and psoriasis: Is there any association between the severity of the disease and adherence to the Mediterranean diet? J Transl Med. (2015) ;13: (1):18. |
[15] | Hatmi Z , Tahvildari S , Motlag AG , Kashani AS . Prevalence of coronary artery disease risk factors in Iran: A population based survey. BMC Cardiovascular Disorders. (2007) ;7: (1):32. |
[16] | Martínez-González MA , Fernández-Jarne E , Serrano-Martínez M , Marti A , Martinez JA , Martín-Moreno JM . Mediterranean diet and reduction in the risk of a first acute myocardial infarction: Anoperational healthy dietary score. European Journal of Nutrition. (2002) ;41: (4):153-60. |
[17] | Cortina JM . What is coefficient alpha? An examination of theory and applications. Journal of Applied Psychology. (1993) ;78: (1):98. |
[18] | Schröder H , Marrugat J , Vila J , Covas MI , Elosua R . Adherence to the traditional Mediterranean diet is inversely associated with body mass index and obesity in a Spanish population. The Journal of Nutrition. (2004) ;134: (12):3355-61. |
[19] | Dernini S , Berry EM . Mediterranean diet: From a healthy diet to a sustainable dietary pattern. Frontiers in Nutrition. (2015) ;2: :15. |
[20] | http://www.internationaloliveoil.org/documents/viewfile/6770-iran |
[21] | |
[22] | El Rhazi K , Nejjari C , Romaguera D , Feart C , Obtel M , Zidouh A , et al. Adherence to a Mediterranean diet in Morocco and its correlates: Cross-sectional analysis of a sample of the adult Moroccan population. BMC Public Health. (2012) ;12: (1):345. |
[23] | 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: (6):1150-6. |
[24] | Martínez-González MA , García-Arellano A , Toledo E , Salas-Salvado J , Buil-Cosiales P , Corella D , et al. A 14-item Mediterranean diet assessment tool and obesity indexes among high-risk subjects: The PREDIMED trial. PLoS One. (2012) ;7: (8):e43134. |
[25] | Pitsavos C , Panagiotakos DB , Tzima N , Chrysohoou C , Economou M , Zampelas A , et al. Adherence to the Mediterranean diet is associated with total antioxidant capacity in healthy adults: The ATTICA study. Am J Clin Nutr. (2005) ;82: (3):694-9. |
