Background

Does the occurrence of type 2 diabetes (T2D) affect the morbidity and mortality of cardiovascular diseases (cerebrovascular disease, coronary heart disease (CHD), and peripheral vascular disease) among adults of Indian descent in rural India?  

Background

Diabetes is endemic in India (Anjana, et al., 2011; International Diabetes Federation, 2013). According to a 2017 report by the International Diabetes Federation (IDF), India ranks second (behind China) on the list of the top ten countries with the highest number of living with diabetes. On the actual prevalence, approximately 65 million persons live with T2D and this number is bound to double within two decades (IDF, 2017). In urban India, the reported prevalence of diabetes is the highest worldwide and it is only comparable to that of nations of West Asia and Pacific (Ramachandran, et al., 2010). However, minimal data is available for rural India where more than 70% of the population lives. Reference can only be drawn to a 2005 study by Yusuf, et al., (2005) who claimed that t rural India may soon experience the same trends as those of urban India. It is an established fact that cardiovascular diseases are the chief causes of morbidity and mortality in T2D. about sixty to eighty percent of persons who present with diabetes succumb to cardiovascular events. The increased risk is attributed to the high prevalence of major cardiovascular risk factors, as well as those for diabetes. Hypertension, smoking and lipid abnormalities for the former and diabetic dyslipidaemia and hyperglycaemia for the latter. (Fonseca, et al., 2006) 

Controlling cardiovascular risk factors among diabetics can delay or prevent cardiovascular disease. A number of studies do report on the effectiveness of therapies that are directed at controlling blood pressure and low-density lipoprotein cholesterol in the prevention of macrovascular events in diabetes (Bangalore, et al., 2011; de Vries, et al., 2012). According to Sridhar, and fellows (2010), there is a significant prevalence of metabolic cardiovascular risk factors among clinic-based Indian patients presenting with diabetes. There are minimal studies which have established the incidence of risk factors for cardiovascular disease among inhabitants of rural India. A further review of literature yields nil results with regard to the number of studies that have evaluated whether Indians presenting with diabetes have the awareness, and also seek treatment for, or control of high blood pressure (hypertension) and high cholesterol (hypercholesterolemia) which stand as the two most important risk factors for cardiovascular disease among this population.

Controlling Cardiovascular Risk Factors among Diabetics

As such, this study seeks to determine the prevalence of diabetes and cardiovascular risk factors in population-based patients in rural India presenting with diabetes. Further, the study seeks to investigate the people’s awareness, treatment, and control of hypertension and hypercholesterolemia – the most important risk factors for cardiovascular events.

Study Design

This study will adopt a multi-site exploratory study design to identify the prevalence of risk factors for cardiovascular diseases among adults who live in rural India and present with diabetes. The rationale for choosing this design is that multisite studies do provide large, diverse samples with sufficient statistical power to detect association between the variables under study, the findings are also more generalizable compared to studies conducted in a single site, and as a result, can provide a true picture of the real situation on the ground. Further, an exploratory design spread across various reasons will be able to show the differences and similarities in the different regions of the country. There is also the illustrated need to perform multisite studies for the determination of the prevalence of cardiovascular risk factors and their trends across rural regions of India, as the methodology has been successfully adopted elsewhere.  The United States National Health and Nutrition Evaluation Surveys (Schargrodsky, et al., 2008), The British Regional Heart Study (Walker, et al., 2004), and other studies across Europe have been able to successfully report on the variable prevalence of risk factors

Neither a cohort study nor a case-control study could be adopted for this study as both designs take a significant amount of time for follow-up.

Population

Approximately 70% (885,393,900) of Indian’s population lives in rural areas (Ministry of Home Affairs, Government of India, 2013). The reported prevalence of diabetes in rural India varies. While the WHO criteria and American Diabetes Association reports it to be 2.7% and 1.9% respectively, other studies such have demonstrated a prevalence of as high as 12.5% and 13.2% in rural Kerala and Andhra Pradesh respectively (Misra, et al., 2011). This study adopts the WHO criteria. Therefore, approximately 23, 905, 635 persons are eligible for this study.

However, due to financial and time constraints, a careful sampling methiodal will have to be adopted to ensure inclusivity in a smaller sample.

Purposive sampling will be adopted for the selection of the sites while simple cluster sampling will be performed at each site for the purposes of selecting the participants. A list of rural areas based on municipal classification will be obtained by the researcher from the respective authority. The investigator will then purposively select the sample size based on some predefined criteria based on demographic characteristics, level of living, occupation, per capita income, development, economic activity and rate of population growth (Sanghvi, 2015). In the identified areas, the researcher will identify a sample size of about 250 men and 250 women (n=500). According to WHO, such a sample size is adequate in identifying a 20% difference in the mean level of biophysical and biochemical risk factors (Luepker, 2004). The investigator will aim a sample of 6,000 that will be spread across approximately 24 rural sites.  At least 800-1000 eligible participants will be invited at each site so as to ensure the participation of at least 500 of them assuming a response rate of 70% as observed in studies conducted earlier (Gupta, et al., 2002; Gupta, et al., 2014).

Study Design

Data Collection

A developed uniform protocol will be adopted across all sites. Surveys will be preceded by meetings with community leaders to drum support for favourable participation. The participants will then be invited in their fasting state to a health facility with each site, depending on the researcher’s schedule. Research assistants will inquire details from a participant and then fill a study case report. Other than demographic data, information on socioeconomic status as depicted by educational level, type of family, disease history, history of known high blood pressure, lipid abnormalities, diabetes and cardiovascular diseases will also be sought. Details will also be inquired on smoking habits (type and number), and alcohol consumption habits. While focused questions will be used to obtain details of other diet and physical activity.

Measurements of height, weight, and waist and hip circumference will also be taken as using standardised equipment as per the WHO guidelines (Luepker, 2004). Sitting blood pressure will also be measured at least 5-minute rest using standardised instruments. For BP, at least 3 readings will be taken and then averaged. Technicians at the respective health centres will be tasked with taking fasting blood samples from the participants after fasting for at least 8 to 10 hours. Blood glucose will be analysed at the laboratories of the facilities while blood for cholesterol, cholesterol lipoproteins, and triglyceride estimation will be transported under recommended conditions to a nearby referral laboratory. Cholesterol, triglyceride and high-density lipoprotein (HDL) cholesterol levels will be measured using enzyme-based assays. The Friedwald’s equation will be used to calculate LDL cholesterol (Gupthaa, et al., 2014). It should be noted that a uniform laboratory protocol will be used for all measurements.

Data Analysis

Both STATA 15 for Windows (STATA Co., College Station, TX, USA) and SPSS package 20.0 version (SPSS Inc, Chicago, Illinois, USA). The values for either gender will be analysed separately. Means and percentages with 95% confidence intervals adjusted for age will be given for continuous carriables and categorical variables respectively. Age adjustment will be performed by direct standardization method based on the 2011 census data before performing statistical tests. the prevalence of the different risk factors in subjects with diabetes and those without will be reported and significance of differences evaluated using the Mantel-Haenszel X² test. p Values <0.05 will considered significant.

Ethical issuesThe study will be conducted in line with the Declaration of Helsinki (Snezana, 2001). Permission will be sought from the Institutional Ethics Committee and the administration of the local authorities and health facilities. Leaders of respective rural areas will also be invited for discussions, they will be oriented on the purpose of the study and will also be requested to comment on the study and encourage participation of their people.

Population

Informed verbal consent will be obtained from all participants. The rationale for verbal consent is pegged on the fact that approximately 35.7% (86 million) Indians in rural India are illiterate (Ministry of Rural Development Government of India, 2012), therefore, a written consent could lead to a selection bias. Before enrolling for the researcher will read out to each potential participant the purpose of the study and seek their consent to be included in the study. The investigator will also inform them that they were free to refuse or drop out of the study at any given time.

Collected data will be stored in such a way that separated personal identifiers from the samples and collected data on the survey tool. As such, there will be no way one can identify the participants through the identifiers.

All patients will receive a hardcopy of their laboratory results. Those exhibiting abnormal test results will be encouraged and facilitated to seek appropriate health services. On the other hand, those diagnosed with diabetes, cardiovascular diseases or presented with risk factors for either will be recruited into respective prevention intervention programs.

References

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