STATISTICAL ANALYSIS OF RELATIONSHIP BETWEEN MEDITERRANEAN DIET ADHERENCE AND CARDIOVASCULAR DISEASE INCIDENCE IN MIDDLE-AGED ADULTS: A CROSS-SECTIONAL STUDY IN KERALA, INDIA

Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 17 STATISTICAL ANALYSIS OF RELATIONSHIP BETWEEN MEDITERRANEAN DIET ADHERENCE AND CARDIOVASCULAR DISEASE INCIDENCE IN MIDDLE-AGED ADULTS: A CROSS-SECTIONAL STUDY IN KERALA, INDIA Abstract: Background: Heart diseases and strokes are still India's top cause of death, and Kerala has especially high rates of these illnesses. The Mediterranean diet (MD) has been shown to protect heart health in Western cultures, but its use in India has not been fully studied. Objective: The goal is to look into the statistical link between following a Mediterranean diet and the risk of heart disease in middle-aged people in Kerala, India, ages 40 to 65. Methods: A cross-sectional study was done with 850 people from Kerala's cities and rural areas. A modified Mediterranean Diet Adherence Screener (MEDAS) was used to measure how well people stuck to the Mediterranean diet. The rate of CVD was found by looking at clinical diagnoses and medical data. Chi-square tests, logistic regression, and association analysis were used for statistical studies. Results: Following the Mediterranean diet more closely was linked to a lower risk of CVD (OR=0.43, 95% CI: 0.28–0.67, p<0.001). The risk of CVD was 57% lower in people who followed their MD closely than in people who didn't. Age, level of physical exercise, and smoking status were found to be important factors. Conclusion: Following the Mediterranean diet is strongly linked to a lower risk of CVD in middle-aged people in Kerala. This suggests that dietary changes could be used to help avoid CVD. Keywords: Mediterranean diet, cardiovascular disease, Kerala, statistical analysis, middle-aged adults, dietary patterns. Information about the authors Sankar Goswami Department of Statistics, Gurucharan College, Silchar, Assam, India 1. Introduction Approximately 28.1% of all deaths in India are caused by cardiovascular diseases (CVD). Kerala has the highest rate of CVD in India, at 13.5% (Prabhakaran et al., 2018). This high rate of CVD is partly due to changes in lifestyle and food that have happened in Kerala during the epidemiological transition (Thankappan et al., 2016). Traditional Indian meals have parts that are good for your heart, but as people have moved to cities, they have started eating more processed carbohydrates and saturated fats, which are bad for your health (Sharma et al., 2020). The Mediterranean diet, which includes lots of fruits, veggies, whole grains, legumes, olive oil, and fish, has been shown to protect heart health in both European and American communities (Estruch et al., 2018). The important PREDIMED study showed that people who followed a high-MD diet had 30% fewer cardiovascular events (Martínez-González et al., 2019). However, these results may not be Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 18 applicable to Indian communities because of differences in genetics, current dietary habits, and socioeconomic factors. Kerala is a unique place for this study because 93.91% of its people can read and write, the state has good healthcare facilities, and there has been a recorded nutrition shift (Kutty et al., 2020). Some parts of the state's traditional diet are similar to Mediterranean diets, like eating a lot of legumes and coconut oil, but other parts are very different (Srinivasan & Misra, 2021). Research Gap: Even though there is a lot of data from Western populations, not much study has been done on the Mediterranean diet and CVD in Indian populations, especially using rigorous statistical methods that take into account how the Indian diet has changed over time. Study Objectives: 1. Assess Mediterranean diet adherence levels among middle-aged adults in Kerala 2. Determine CVD incidence rates across different MD adherence categories 3. Analyze the statistical relationship between MD adherence and CVD incidence 4. Identify potential confounding variables influencing this relationship 2. Methods 2.1 Study Design and Population This cross-sectional study took place in four districts of Kerala from January 2022 to December 2023. The districts were Thiruvananthapuram, Ernakulam, Kozhikode, and Thrissur. Adults between the ages of 40 and 65 who had lived in Kerala for at least 10 years were the focus group. Using a 95% confidence level, 80% power, and an estimated effect size of 0.3 to figure out the sample size, 782 people were needed. To account for 10% who didn't respond, 850 participants were recruited. 2.2 Method of Sampling A method called multi-stage stratified random sampling was used. First, two taluks were picked at random from each district. After that, primary health centers (PHCs) were used to recruit people, with listed people aged 40 to 65 being chosen at random. The ratio of urban to rural representatives stayed at 60%, which is in line with Kerala's population split. 2.3 Evaluation of Diet A Mediterranean Diet Adherence Screener (MEDAS) that was widely adapted and changed for the Indian setting was used to measure diet adherence. The 14-item quiz measured how often key MD components were taken in: ➢ Olive oil or coconut oil as principal fat ➢ Vegetables (≥2 servings/day) ➢ Fruits (≥3 servings/day) ➢ Red meat and processed meat (<1 serving/day) ➢ Butter, margarine, cream (<1 serving/day) ➢ Sugar-sweetened beverages (<1 serving/day) ➢ Legumes (≥3 servings/week) ➢ Fish/seafood (≥3 servings/week) ➢ Nuts (≥3 servings/week) ➢ Whole grains preference Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 19 ➢ Tomatoes, onions, garlic sofrito (≥2 servings/week) Scores ranged from 0-14, categorized as: Low adherence (0-5), Moderate adherence (6-9), High adherence (10-14). 2.4 CVD Assessment CVD incidence was determined through: 1. Self-reported physician diagnosis 2. Medical record verification 3. Current medication for CVD 4. ECG abnormalities 5. Previous cardiovascular events (myocardial infarction, stroke, revascularization) 2.5 Covariates Standardized protocols were used to collect demographic information (age, gender, education level, and income), anthropometric information (BMI, waist size), lifestyle information (physical exercise, smoking, and alcohol use), and clinical information (blood pressure, fasting glucose, and lipid profile). 2.6 Analysis of Statistics Python 3.9 with the pandas, scipy, statsmodels, and matplotlib tools were used to analyze the data. Means, standard deviations, and frequency distributions were all types of descriptive statistics. Independent t-tests were used to compare continuous factors, while Chi-square tests looked at category relationships. Taking into account other factors, logistic regression models looked at the link between following your doctor's orders and CVD. The level of statistical significance was set at 0.05. 2.7 Ethical Considerations The Institutional Ethics Committee gave its approval to the study. All subjects gave their written permission after being fully informed. The privacy of the data was kept at all times. 3. Results 3.1 Participant Characteristics Table 1 shows information about the 850 subjects at the start of the study. The average age was 52.4 years old, with 7.2 years of variation. 52.5% of the people were women. 28.2% (n=240) of people had CVD. Age, BMI, smoking status, and amount of physical exercise were all very different between the CVD and non-CVD groups. Table 1: Baseline Characteristics of Study Participants (N=850) Characteristic Total (N=850) CVD Group (n=240) Non-CVD Group (n=610) p-value Age (years), mean±SD 52.4±7.2 56.1±6.8 50.9±7.0 <0.001 Female, n (%) 446 (52.5) 118 (49.2) 328 (53.8) 0.236 BMI (kg/m²), mean±SD 26.3±4.1 27.8±4.3 25.7±3.9 <0.001 Current smoker, n (%) 178 (20.9) 68 (28.3) 110 (18.0) 0.002 Physical activity (METmin/week) 1847±856 1425±742 2018±861 <0.001 Systolic BP (mmHg) 128.4±16.2 136.2±18.4 125.3±14.2 <0.001 Total cholesterol (mg/dL) 198.5±42.3 212.4±45.2 192.8±40.1 <0.001 Fasting glucose (mg/dL) 104.2±28.6 112.8±32.4 100.9±26.2 <0.001 Urban residence, n (%) 510 (60.0) 156 (65.0) 354 (58.0) 0.071 Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 20 3.2 Mediterranean Diet Adherence Distribution Mediterranean diet adherence scores ranged from 2 to 13 (mean=7.4±2.8). Distribution across categories: Low adherence (28.5%, n=242), Moderate adherence (48.8%, n=415), High adherence (22.7%, n=193). Figure 1 illustrates the distribution of MEDAS scores stratified by CVD status. 3.3 Association Between Mediterranean Diet Adherence and CVD Table 2 shows a strong negative relationship between following your doctor's orders and the risk of CVD. After taking into account other factors, high adherence was linked to 57% lower chances of CVD compared to low adherence (OR=0.43, 95% CI: 0.28–0.67, p<0.001). Table 2: Association Between Mediterranean Diet Adherence and CVD Incidence MD Adherence CVD Cases/Total Prevalence (%) Crude OR (95% CI) Adjusted OR* (95% CI) p-value Low (0-5) 102/242 42.1 1.00 (Reference) 1.00 (Reference) - Moderate (6-9) 110/415 26.5 0.49 (0.36-0.68) 0.58 (0.41-0.82) 0.002 High (10-14) 24/193 12.4 0.20 (0.12-0.32) 0.43 (0.28-0.67) <0.001 *Adjusted for age, sex, BMI, smoking status, physical activity, education level, and urban/rural residence 3.4 Individual MEDAS Components and CVD Risk The link between each part of the Mediterranean diet and CVD is shown in Table 3. Using olive or coconut oil as your main fat (OR=0.61), eating more vegetables (OR=0.54), eating fish (OR=0.58), and nuts (OR=0.63) were all linked to lower risk. Table 3: Association of Individual MEDAS Components with CVD MEDAS Component Met Criteria (%) CVD Met Criteria (%) Non-CVD OR (95% CI) p-value Olive/coconut oil principal fat 32.5 48.2 0.61 (0.45-0.82) 0.001 Vegetables ≥2 servings/day 28.8 45.6 0.54 (0.40-0.73) <0.001 Fruits ≥3 servings/day 35.4 52.1 0.68 (0.51-0.91) 0.009 Red meat <1 serving/day 45.0 56.7 0.75 (0.56-1.00) 0.048 Butter/cream <1 serving/day 52.1 58.9 0.84 (0.63-1.12) 0.228 Sugary beverages <1/day 38.3 54.3 0.66 (0.49-0.88) 0.005 Legumes ≥3 servings/week 61.3 68.5 0.79 (0.58-1.07) 0.126 Fish ≥3 servings/week 33.8 49.3 0.58 (0.43-0.78) <0.001 Nuts ≥3 servings/week 25.4 36.9 0.63 (0.46-0.87) 0.005 Whole grains preference 42.5 51.8 0.71 (0.53-0.95) 0.020 Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 21 3.5 Dose-Response Relationship The dose-response relationship between MEDAS score and CVD risks ratio is shown in Figure 2. It shows a linearly negative relationship (p for trend <0.001). 3.6 Subgroup Analysis Table 4 shows studies of subgroups based on gender, BMI, and smoking status. The protective effect of high MD adherence stayed significant across all classes, with bigger effects seen in men (OR=0.38) and people who don't smoke (OR=0.41). Table 4: Subgroup Analysis of Mediterranean Diet Adherence and CVD Subgroup High vs Low Adherence OR (95% CI) p-value p for interaction Gender 0.042 Male 0.38 (0.21-0.68) 0.001 Female 0.51 (0.29-0.89) 0.018 BMI Category 0.156 Normal (<25 kg/m²) 0.46 (0.24-0.88) 0.019 Overweight (25-29.9) 0.42 (0.23-0.76) 0.004 Obese (≥30) 0.38 (0.18-0.79) 0.010 Smoking Status 0.028 Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 22 Never smoker 0.41 (0.25-0.68) <0.001 Former smoker 0.48 (0.22-1.04) 0.063 Current smoker 0.72 (0.32-1.62) 0.428 Physical Activity 0.089 Low (<1500 MET-min/week) 0.52 (0.29-0.93) 0.028 High (≥1500 MET-min/week) 0.37 (0.21-0.66) 0.001 3.7 Multivariate Analysis Multiple logistic regression analysis (Table 5) showed that following your doctor's orders is a strong indicator of CVD even when other common risk factors are taken into account. Each unit rise in the MEDAS score was linked to a 15% drop in the risk of CVD (OR=0.85, 95% CI: 0.80-0.91, p<0.001). Table 5: Multiple Logistic Regression Model for CVD Prediction Variable β Coefficient OR (95% CI) p-value MEDAS score (continuous) -0.162 0.85 (0.80-0.91) <0.001 Age (per year) 0.068 1.07 (1.04-1.10) <0.001 Male gender 0.324 1.38 (0.96-1.99) 0.081 BMI (per kg/m²) 0.087 1.09 (1.04-1.14) <0.001 Current smoking 0.556 1.74 (1.18-2.58) 0.005 Physical activity (per 100 MET-min/week) -0.042 0.96 (0.93-0.99) 0.012 Systolic BP (per mmHg) 0.025 1.03 (1.01-1.04) <0.001 Total cholesterol (per mg/dL) 0.008 1.01 (1.00-1.01) 0.033 Family history CVD 0.682 1.98 (1.42-2.76) <0.001 Urban residence 0.215 1.24 (0.88-1.75) 0.218 Model statistics: χ²=186.4, p<0.001; Pseudo R²=0.324; Hosmer-Lemeshow test p=0.412; AUC=0.798 4. Discussion This study shows that middle-aged people in Kerala, India who follow a Mediterranean diet are less likely to get cardiovascular disease. A 57% drop in the risk of CVD was seen in high adherents compared to low adherents, which shows clinical impact similar to drug treatments. These results show that the Mediterranean diet can help people from India as well as Western countries, even though their physical, cultural, and food backgrounds are different. 4.1 A Comparison with Previous Work Our results are similar to the 30% lower chance of heart disease found in the PREDIMED trial (Estruch et al., 2018), but our study had greater effects. This could be because the cross-sectional design allowed us to see the cumulative effects of the diet. Rosato et al. (2019) did a meta-analysis and found a pooled OR of 0.69 for CVD in people who closely followed their doctor's advice. Our study found an OR of 0.43, which suggests that the effects might be bigger in places like Kerala where CVD risk is already high. The Indo-Mediterranean Diet Heart Study by Singh et al. (2002) found that Indian heart patients who changed their diet to a Mediterranean one had 52% fewer cardiac events. This supports our results in a primary prevention setting. But because they did their intervention study in North India, it can't be used in other places because of the way people eat and their genetic makeup are different in Kerala. 4.2 Thoughts on Mechanisms Mediterranean food can help protect heart health by lowering inflammation, improving lipid profiles, lowering oxidative stress, and supporting gut bacteria regulation (Widmer et al., 2015). In our study, the factors that showed the greatest links were eating vegetables, fish, and healthy oils. These factors contain Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 23 bioactive substances (polyphenols, omega-3 fatty acids, and monounsaturated fats) that work on multiple CVD pathways at the same time. The way people in Kerala have traditionally used coconut oil, which we copied in the MEDAS, contains medium-chain triglycerides that might be good for your metabolism, even though they contain saturated fat (Narayanankutty et al., 2018). This culture adaptation stays true to the principles of the Mediterranean diet while taking into account what foods are available and acceptable in the area. 4.3 Changes to public health Because of the high rate of CVD in Kerala, these results show that dietary interventions based on the Mediterranean diet could greatly lower the number of people who get sick. Because of the dose-response relationship, even small changes in the quality of the food have positive effects. This means that population-wide treatments are possible. Cost-effectiveness could be improved by combining it with other public health projects, such as Kerala's Non-Communicable Disease Prevention Program. The stronger protective benefits in men and people who didn't smoke show that focused interventions might work, even though everyone gained. Even after taking into account socioeconomic factors, the persistent link shows that changing one's food is a fair measure that can be used by people of all income levels. 4.4 Strengths and Limitations The study's strengths are its (1) large, well-characterized sample that is representative of Kerala's population; (2) a validated dietary assessment tool that has been adapted for use in India; (3) thorough statistical analysis that includes dose-response relationships and subgroup analyses; and (4) the ability to account for multiple confounders. Limitations should be taken into account: (1) The cross-sectional design makes it impossible to draw conclusions about causes—reverse causation (CVD diagnosis leading to dietary changes) can't be ruled out; (2) the dietary assessment was based on self-report, which can be affected by recall bias and social desirability; (3) residual confounding from unmeasured variables (genetic factors, childhood nutrition) is still possible; (4) the CVD diagnosis combined self-report with medical records, which could lead to wrongly classifying subclinical disease; and (5) the study's generalizability to other parts of India needs to be proven because Kerala is so different. 4.5 Directions for Future Research Prospective cohort studies that keep track of CVD events that happen over long periods of time would establish time and make it easier to figure out what caused what. Randomized controlled studies that adapt Mediterranean diet interventions for Indian people would give doctors solid proof for their suggestions. Studying how genes and food affect each other, taking Kerala's genetic background into account, could help make dietary suggestions more specific to each person. Comparing dietary treatments to drug-based methods would help with allocating resources through economic studies. Biomarker studies (such as inflammatory markers, fatty subfractions, and metabolomics) would help us figure out how things work in Indian communities. 5. Conclusion This study shows that among middle-aged people in Kerala, India, following a Mediterranean diet is strongly and statistically significantly linked to a lower risk of cardiovascular disease. A dose-response link supports the idea that high adherence lowers the risk of CVD by 57% compared to low adherence. Some parts of a healthy diet, like eating plenty of vegetables, fish, and healthy oils, have their own beneficial effects. These results show that following the Mediterranean diet, with some changes made to fit the Indian setting, is a good, scientific way to keep people in Kerala who are at high risk for CVD from getting it. Journal of Science, Research and Teaching Vol. 3, No. 10, Oct - 2024 ISSN: 2181-4406 24 The large effect sizes seen suggest that food treatments that are added to current prevention programs could have a real effect on public health. But because the study was cross-sectional, it's important to be careful when figuring out what caused what. It is important to do prospective studies and controlled trials to confirm these links and make the Mediterranean diet a proven way for Indian people to avoid heart disease. 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