Diabetes and correlates of cardiovascular diseases among women aged 15-49 years in Benin: evidence from a Demographic and Health Survey

Background: Sub-Saharan Africa (SSA) countries are facing an epidemiological shift from infectious diseases to chronic diseases, such as cardiovascular diseases (CVDs). The burden of CVDs in a population results from the prevalence of several factors. This study was to determine the association of diabetes and correlates with heart and lung diseases. Methods: We used Benin Demographic and Health Survey (BDHS) population-based cross-sectional data. BDHS 2017-18 is the fth of its kind. A total of 7712 women of reproductive age were included in this study. Heart and lung diseases were the outcome variables. Percentage and logistic regression model were used to analyze the data. The level of statistical signicance was set at 5%. Results: The prevalence of heart disease was 1.3% (95%CI: 1.0%-1.7%) and lung disease was approximately 1.5% (95%CI: 1.2%-1.9%). Women who had diabetes were also found to be 3.57 times signicantly more likely to have heart disease when compared with those who do not have diabetes (AOR= 3.57; 95%CI: 1.51 – 8.45). Furthermore, women with diabetes were 4.55 times signicantly more likely to also have lung diseases when compared with those who do not have diabetes (AOR= 4.55; 95%CI: 2.06 – 10.06). Women who had hypertension were found to be 3.18 times signicantly more likely to have heart disease when compared with those who had no hypertension (adjusted odds ratio (AOR) = 3.18; 95%CI: 2.02 – 4.98). Conclusion:

Regardless of this burden, the sub-region is now witnessing a rapid epidemiological evolution which is characterized by a move from dominance of communicable diseases to non-communicable ones, just as its being observed in many other low and middle-income economies around the globe (13). Nevertheless, there is a growing research indicating that disease conditions such as diabetes (14,15) lung-related and respiratory diseases (16), and other CVDs (17,18), have now become serious disease-burden in many SSA countries. Risk factors for lung and heart diseases' surveillance in SSA for the past three to four decades show that majority of young adults are exposed to one or more NCDs risk factors. These risk factors include tobacco and excessive alcohol use, poor diet, sedentary lifestyle, hypertension as well as overweight or obesity (19).
In the SDGs, the challenges of the NCDs across the globe were put into consideration. The document targets the reduction by 30% by the year 2030, including all premature deaths caused by the foremost NCDs such as lungs and heart-related diseases. It also targets the promotion of general wellbeing and mental health, as enshrined in the SDGs goal 3 (11,20). This is also one of the targets of the Global NCDs Action Plan 2013-2020 (21). The achievement of these targets by any of the countries in SSA, such as Benin Republic, will be dependent on a total overhauling of the health systems by making sure all the bottlenecks such as underfunding, poor and inadequate training and poor equipment of the health sector, are arrested. The majority of the health systems in SSA are fragmented, under-funded, fragile and infrastructurally limited to handle this ever-increasing communicable and non-communicable disease burden (22,23). In light of the above, we undertook this study to examine the association between diabetes and correlates of cardiovascular diseases among women aged 15-49 years in Benin.

Data source
We used BDHS population-based cross-sectional data. BDHS 2017-18 is the fth of its kind. A total of 7712 women of reproductive age were included in this study. BDHS used a strati ed multi-stage cluster random sampling technique for the data collection. Data was collected on vital reproductive health issues via structured interviewer-administered questionnaires. DHS program was established by the United States Agency for International Development (USAID) in 1984. It was designed as a follow-up to the World Fertility Survey and the Contraceptive Prevalence Survey projects. It was rst awarded in 1984 to Westinghouse Health Systems (which subsequently evolved into part of OCR Macro). The project has been implemented in overlapping ve-year phases; DHS-I ran from 1984 to1990; DHS-II from 1988 to1993; and DHS-III from 1992 to1998. In 1997, DHS was folded into the new multi-project MEASURE program as MEASURE DHS+. Since 1984, more than 130 nationally representative household-based surveys have been completed under the DHS project in about 70 countries.
Many of the countries have conducted multiple DHS to establish trend data that enable them to gauge progress in their programs. Countries that participate in the DHS program are primarily countries that receive USAID assistance; however, several non-USAID supported countries have participated with funding from other donors such as UNICEF, UNFPA or the World Bank. DHS are designed to collect data on fertility and reproductive health, child health, family planning and HIV/AIDS. Due to the subject matter of the survey, women of reproductive age  are the main focus of the survey. Women eligible for an individual interview are identi ed through the households selected in the sample. Therefore, all DHS surveys utilize a minimum of two questionnaires-a Household Questionnaire and a Women's Questionnaire. DHS data is publicly available and can be accessed from the MEASURE DHS database at http://dhsprogram.com/data/available-datasets.cfm. DHS are usually implemented by the National Population Commission (NPC) with nancial and technical assistance by ICF International provisioned through the USAID-funded MEASURE DHS program. DHS involved multi-stage strati ed cluster design based on a list of enumeration areas (EAs), which are systematically selected units from localities and constitute the Local Government Areas (LGAs). Details of the sampling procedure have been reported previously (24).

Geography of Benin
The country spans from north to south and indeed a long stretched country in West Africa, which is The chronic diseases were measured dichotomously (yes vs. no) as reported by the women; "In the past 12 months, ever told has heart disease" and "ever diagnosed with lung disease by doctor or nurse".

Explanatory variables
Hypertension and diabetes were measure dichotomously (yes vs. no); usage of tobacco products/cigarette (use vs. not use); ever used anything to delay getting pregnant (yes vs. no); parity: 1-2/3-4/>4/no birth; total lifetime number of sex partners: Alibori/Atacora/Atlantique/Borgou/Collines/Couffo/Donga/Littoral/Mono/ Quémé/Plateau and Zou; place of residence: urban/rural; marital status: not married/currently married or living with a partner/formerly married; maternal education: no formal education/primary/secondary+; participation in the labour force: working vs. not working; covered by health insurance: covered vs. not covered. Household wealth quintile: principal components analysis (PCA) was used to assign the wealth indicator weights. This procedure assigned scores and standardized the wealth indicator variables such as; bicycle, motorcycle/scooter, car/truck, main oor material, main wall material, main roof material, sanitation facilities, water source, radio, television, electricity, refrigerator, cooking fuel, furniture, number of persons per room. The factor coe cient scores (factor loadings) and z-scores were calculated. For each household, the indicator values were multiplied by the loadings and summed to produce the household's wealth index value. The standardized z-score was used to disentangle the overall assigned scores to the poor/middle/rich categories (27,28).

Ethical consideration
We utilized population-based secondary datasets available in the public domain/ online with all identifier information removed. The authors were granted access to use the data by MEASURE DHS/ICF International. DHS Program is consistent with the standards for ensuring the protection of respondents' privacy. ICF International ensures that the survey complies with the U.S. Department of Health and Human Services regulations for the respect of human subjects. No further approval was required for this study. More details about data and ethical standards are available at http://goo.gl/ny8T6X.

Analytical approach
We used the built-in survey command of Stata for all analyses to account for the sampling strata, primary sampling unit, and sampling weight provided in the dataset. Prevalence of the heart and lung diseases were reported in percentages. The correlation matrix was used to conduct multicollinearity diagnostics to examine the interdependence between explanatory variables using a cut-off minimum of 0.8 known to cause concerns in multicollinearity (29). All signi cant variables in the unadjusted logistic regression model were retained in the model due to lack of collinearity. Multivariable binary logistic regression was used to analyze the data. The level of statistical signi cance was set at 5%. All data analyses were conducted using Stata 14.0 (StataCorp, College Station, Texas, United States of America).

Results
The prevalence of heart disease was 1.3% (95%CI: 1.0%-1.7%). Results from Table 2 showed 4.7% and 8.4% of women, who had hypertension and diabetes respectively, also had heart diseases, in contrast to 1.0% and 1.2% of those who do not have hypertension and diabetes but have heart disease respectively. Women who had hypertension were found to be 3.18 times more likely to have heart diseases when compared with those who had no hypertension (AOR = 3.18 95%CI: 2.02-4.98). Those who had diabetes were also found to be 3.57 times more likely to have heart disease when compared with those who do not have diabetes (AOR = 3.57; 95%CI: 1.51-8.45). Furthermore, women aged 30-34 years were 3.49 times as likely to have heart disease when compared with women aged 15-19 years (AOR = 3.49; 95%CI: 1.18, 10.31). The geographical region was also signi cantly associated with heart disease (See Table 1 for the details).  Table 2 for the details).

Discussion
This study is the rst of its kind in the provision of a nationwide report of the prevalence of heart and lung diseases among women of reproductive age in the Republic of Benin, West Africa. Some studies from other SSA countries have reported ndings similar to the one reported here. However, no report has been made on the status of heart and lung diseases and their relationship with hypertension and diabetes among reproductive-age women in Benin Republic.
The prevalence of lung and heart diseases as observed in this study were approximately 2% each. This is similar to the 2.4% reported in Yaounde, Cameroon (30), but lower than 20.2% reported in urban and rural Uganda (31) and 17.8% reported in Abeshge District of Ethiopia (32). Reports by several researchers show that the prevalence of chronic obstructive pulmonary disease, which is the third leading cause of mortality caused by non-communicable diseases globally (10), in SSA ranges from 4.1% − 22.2% (33). The difference observed in this study may be interpreted to be due to the fact that this study utilizes a national data and in this case, only the known cases of lung and heart diseases are reported as the interviewers did not screen the participants to clearly determine those that have lung and hearts diseases, but depended on the medical history supplied to them by the participants. Therefore, there may be some study participants who may have lung or heart disease but because she has not been diagnosed, would have no clue that she has the disease.
This study shows that 4.7% and 8.4% of women, who had hypertension and diabetes respectively, also were with known heart diseases, in comparison to 1.0% and 1.2% of those who have heart disease but do not have hypertension and diabetes respectively. Our study observed an association between hypertension and diabetes, and heart diseases. Hypertension and diabetes were risk factors for heart disease. This association is very much in agreement with several studies ndings across SSA countries, which have also come up with reports that hypertension or/and diabetes are risk factors of CVDs; such as Nigeria (34), Cameroon (35,36), Benin (37), and 2010 Global Burden of Diseases report on CVDs in SSA (18). Mandi et al, also reported that hypertension was the most prevalent risk factor of CVD in rural Burkina Faso (38).
More so, a four-country SSA cross-sectional study reported that 50.0% of the people with hypertension that participated in the study were unaware of being hypertensive (39) This implies that the menace of hypertension may be much more that is currently known among SSA population, as some studies have also suggested (40)(41)(42). This therefore, suggests that a large proportion of the region's hypertension cases remain undiagnosed, untreated, or inadequately treated, hence may be the highest contributor for morbidity and mortality caused by complications of CVD (42)(43)(44). Over the past decades, in SSA, the attention of governments and funding agencies have been directed to the ght against communicable diseases such as HIV/AIDS, Tuberculosis, Malaria, with NCDs being neglected or relegated to the background (3,4). The burden of hypertension is such a public health concern as reports have it that it is the single leading cause of death and hospitalization globally (41,(45)(46)(47). The current trends in globalization may have contributed to the rise in the cases of non-communicable diseases in many low and middle-income countries such as SSA countries as lifestyles and dietary habits' changes have occurred among people in low and middle-income economies (19).
Our study also found an association between diabetes and lung diseases among the studied participant.
Approximately 9.6% of those with known lung disease also have diabetes compared with 1.6% who had lung diseases without elevated blood glucose. Several other reports have shown that diabetes is a comorbidity with lung diseases (48)(49)(50)(51)(52)(53)(54). The relationship between lung diseases and diabetes has been extensively studied, though the mechanism with which this association exist has not been well understood. Explanations have been offered on the possible mechanisms; that hyperglycemic effects on the physiologic status of the lungs, in ammatory responses or the lungs susceptibility to infections may be a signi cant contributor to this association (55,56), another possible mechanism is offered by Zheng et al, which attributed the association to a sustained diabetes level resulting in oxidative stress (OS) thereby causing tissue damage (57). Aside from these possibilities, lifestyles such as tobacco use, sedentary life, physical inactivity, air pollution as well as age have been implicated as possible risk factors for both heart and lung diseases (37,51,(58)(59)(60).
This study observed that geographical departments and age of the participants are determining factors for heart and lung diseases. Benin Republic has twelve departments with three of them being essentially urban; Oueme, Littoral and Atlantic, another three are essentially rural; Atakora, Borgou and Zou, while the rest are essentially semi-urban (61,62). We observed that participants from the rural departments were found to be less likely to have heart and lung diseases compared with participants from the essentially urban departments. This nding is in corroboration with the report from South Africa; it was reported that the most developed areas in the study recorded higher heart and lungs diseases (63). Another study has reported that the burden of heart-related diseases was in the urban areas and the densely populated part of the city (60). The study also revealed that the majority of the CVDs were in the elite and middle-class neighborhoods.
Therefore, CVD was predominantly high in rich environment, while generally low in the middle-income and more rural/urban sprawl neighborhoods (60). Two South African studies also are in agreement that heart diseases are higher in urban areas than in rural areas (64,65). The high prevalence observed among participants from urban departments compared with those from the essentially rural departments can be explained in the view of industrialization and urbanization (urban cities come with much day-to-day hustles to catch up with day's activities, stress from tra cs, and vehicular as well as industrial pollutions). People in urban cities are also prone to poor dietary lifestyle as majority often depend on junk foods, sedentary lifestyle or physical inactivity due to o ce work, tobacco use, compared with rural dwellers. Our study revealed that women from the mostly urban departments were more likely to have heart and lung diseases compared with those in the rural departments.

Strengths and limitations
The major strength of this study is the use of nationally representative data and the ndings are generalizable for the women of reproductive age in Benin, West Africa. However, only an association of the factors and not causation can be inferred due to the cross-sectional nature of the data. Also, we were unable to explore other contributory risk factors of heart and lung diseases such as overweight/obesity, salt intake, psychosocial stress, and other endogenous factors.

Conclusion
We found that hypertension was associated with heart disease among women aged 15-49 years in Benin. Health policymakers and government need to focus on widespread prevention and control interventions of heart and lung diseases through improved screening for risk factors and early detection