Socioeconomic Predictors and Cost of Comorbidity Among Indian Population: A Case of Diabetes and Hypertension

Abstract

Purpose

With changing demography and the increasing burden of chronic diseases comorbidity is becoming a major public health concern. Among various co-occurring disease combinations, diabetes and hypertension are the two most fatal combinations often increasing the risk of multimorbidity, complexity, and cost of treatment. Therefore, this study intends to estimate the prevalence of comorbidity in India and across various socioeconomic groups to identify the higher-risk population. We further analysed the economic burden associated with comorbid conditions of diabetes and hypertension in particular.

Data and Methodology

This is a cross-sectional study that uses Unit-Level data from the NSSO-75 round (2017–2018). The marginal effect using the logit model is calculated to identify the higher-risk population for the prevalence of comorbidity across socioeconomic and demographic characteristics. The cost of treatment is calculated through descriptive statistics.

Results and Conclusion

The prevalence of comorbid diabetes and hypertension is 2.06% in India. Heart disease, goiter and thyroid, joint pain, bronchial asthma, and gastric peptic ulcer are the common combinations prevailing among patients with diabetes and hypertension together. Results suggest that the elderly and women are at higher risk of comorbidity. Education and higher economic status are positively associated with it. The cost of treatment increases with comorbidity, and medicine constitutes almost 83.2% of the total medical cost among patients with diabetes and hypertension.

Keywords

Comorbidity diabetes hypertension aging socioeconomic status

Introduction

With the growing aging population and the increasing burden of chronic non-communicable diseases such as diabetes, hypertension, and heart diseases (Habib & Saha, 2010; Omran, 2005), comorbidity or multimorbidity has emerged as a new challenge to the healthcare systems (Fortin, 2007; Pati et al., 2017). Studies from western countries have shown a rising incidence of co-occurring diseases among patients with chronic non-communicable diseases. In a nationally representative study from Scotland across chronic patients, it was found that there were more patients suffering from more than one disease than from a single disease alone (Barnett, 2012). The prevalence of comorbidity varies across studies depending on the methodology, definition, and population size (Diederichs et al., 2011). Across the literature, comorbidity or multimorbidity is defined as the presence of two or more chronic conditions in the same patient (Jakovljević & Ostojić, 2013; van den Akker et al., 1996). Although there is a slight difference between the two, comorbidity means the prevalence of more than one disease with an index disease (Feinstein, 1970; Schellevis et al., 1993) and multimorbidity is simply the presence of two or more diseases irrespective of an index disease (Bayliss et al., 2008). Nevertheless, in this article, we have used the term comorbidity to simply show the prevalence of co-existing diseases among the population. Studies have found that comorbidity is associated with the age and socioeconomic status of the population. Its prevalence increases with age (Fortin, 2005; Marengoni et al., 2011; Wang et al., 2014). However, recent evidence also suggest a growing burden of comorbidity among the population aged below 60 years. It was found in a study that among people suffering from multiple diseases, 42.1% were below 60 years of age (Taylor et al., 2010). In a systematic review, it was found that the prevalence of co-existing diseases was inversely associated with income, education, and employment (Boutayeb et al., 2013). Research on comorbidity has gained importance in the recent past due to the complexity and cost associated with it. Comorbidity leads to chronic health outcomes like fatality, poor quality of life, disability, and mental stress (Arokiasamy et al., 2015; Nunes, 2016; Pati et al., 2019). It is also witnessed in the recent COVID-19 cases, as the pandemic is more fatal to the population having comorbidities such as hypertension and diabetes (Fang et al., 2020; Guan et al., 2020). Comorbidity often elevates the treatment cost and complexity, multiple visits to the doctors, number of hospitalisations, and test (Wolff et al., 2002). It was found in a study that out-of-pocket expenditure among people suffering from comorbidity was 3.3 times higher than those with no comorbidity (Paez et al., 2009). The likelihood that patients with a particular condition such as heart failure or diabetes will use expensive healthcare resources such as hospital care increases substantially with the presence of other comorbidities (Lehnert et al., 2011). In India according to a study by Pati et al. (2017), percentage of participants reporting having any outpatient visits in the last year increased from 71% in those with no NCDs to 83% in those with 3+ NCDs. The mean number of visits to an outpatient department in the preceding 12 months increased from 2.24 in respondents with no NCDs to 6.16 in those with 3+ NCDs. Comorbidity varies across socioeconomic status.

Among various chronic diseases, diabetes and hypertension remain to be the two most frequently co-occurring diseases and their incidence is surging drastically worldwide (Mohan et al., 2013; Nowakowska et al., 2019). It is predicted that by 2030, approximately 87 million people will be afflicted by diabetes in India (Shaw et al., 2010). India is even known as the diabetic capital. Furthermore, hypertension will affect approximately 213.5 million Indians by 2025 (Kearney et al., 2005). These diseases share common risk factors such as a sedentary lifestyle and obesity, and therefore the chances of their co-occurrence are very high (Arije et al., 2007). Studies suggest that the likelihood of the development of hypertension is 1.5–2 times higher among diabetic patients than non-diabetic patients (Arauz-Pacheco et al., 2004). Both diseases are predisposing factors for life-threatening diseases such as cardiovascular disease, renal failure, micro-vascular, and macro-vascular diseases, and when they coexist, the consequences are even worse (Adler, 2000). There are substantial clinical and epidemiological evidence that suggest that these diseases increase the risk of other fatal chronic conditions. In a study, it was found that diabetes and hypertension increase the risk of cardiovascular diseases by 71% (Gress & Wofford, 2000). Management of coexisting diseases is complex, needs special care, and is a patient-centric approach, as one health condition may affect the treatment of another health condition and could increase the complexity (Boyd & Fortin, 2010). This is particularly challenging for a developing country like India, which is still struggling with the management of single diseases. For the policymakers, this is a serious concern as the incidence of these diseases is rising dramatically. Unhealthy dietary patterns and sedentary lifestyles are the driving factors behind the increasing burden of these diseases (González et al., 2017). Furthermore, Indian urban planning is an obesogenic and very small window available for people for exercising leads to a rising incidence. Since both diseases are preventable and can be controlled and prevented by timely diagnosis and other interventions, the estimation and identification of populations at higher risk are imperative for the planning of optimal healthcare delivery and efficient disease management. Most of the studies on comorbidity are from western countries, and there remains a huge gap in the health literature in India. To fill this gap, this study attempts to discern the co-prevalence of diabetes and hypertension across various socioeconomic groups of the population and the economic burden associated with the comorbidity on a large population. Furthermore, it is also important to understand the treatment-seeking pattern and increasing out-of-pocket expenditure associated with it for the health policy in India. This would be of great importance for the policymakers and healthcare system to plan an integrated healthcare model for the treatment of such coexisting diseases.

Data and Methods

We have used nationally representative data from Social Consumption Health survey NSSO 75 Round. NSSO was conducted between July 2017 and June 2018 by the National sample survey organisation India. This is a cross-sectional study that collects data on morbidity, treatment-seeking patterns, and inpatient (in the last 15 days) and outpatient expenditure (in the last 365 days).

Outcome variables: The outcome variables in the study are diabetes and hypertension. It is defined as the presence of both diabetes and hypertension simultaneously among an individual (the person may also have other morbidities along with hypertension and diabetes) who is self-reporting the illness in the last 15 days before the survey.

Furthermore, the prevalence rate is calculated for coexisting diabetes and hypertension among populations across socioeconomic indicators according to the following formula.

Prevalence rate: Total population with coexisting diabetes and hypertension / Total estimated morbid population × 100.

Average total cost: Medical cost + Non-medical cost – Reimbursement (for outpatients, last 15 days before the survey, and inpatients, last 365 days).

Medical cost includes the cost of medicine (both Ayush and non-Ayush), doctors and surgeon fees, diagnostic tests, and other medical expenses. Package components are included in the medical cost for hospitalisation. Non-medical cost includes cost of transportation and other no-medical expenses.

Treatment seeking pattern is calculated both for inpatient (hospitalisation) and outpatient treatment.

The marginal effect using the simple logit model is computed to identify the socioeconomic and demographic characteristics of the population suffering from comorbidity.

Dependent variable: Co-existing diabetes and hypertension (1 = person reporting comorbidity, diabetes and hypertension; 0 = not having comorbidity, diabetes and hypertension).

Explanatory variables: Socioeconomic and demographic indicators are age group, sex, education level, caste, religion, monthly per capita expenditure (taken as a proxy of the standard of living), and primary activity status (to capture work and lifestyle).

Results

Prevalence of Comorbid Diabetes and Hypertension Among Indian Population

In India, approximately 5.1% of the population is suffering from multimorbidity. Of which, approximately 4.1% are having two chronic diseases and 1% have three or more chronic diseases (Table 1). The overall prevalence of diabetes and hypertension in India rose from 10.7% in 2014 to 13.42% and 14.34% in 2018 (Figure 1). Co-prevalence of diabetes and hypertension is approximately 2.06% of the total morbid population (Table 2). Among those populations who are suffering from dual diseases (two diseases at the same time), 35.2% of them have diabetes and hypertension. Among those suffering from three or more diseases, 61.8% of them have diabetes and hypertension along with any other disease (Table 2). The literature also suggests that the co-prevalence of these two diseases increases the chances of the diseases. The average number of diseases among people suffering from diabetes and hypertension simultaneously is 2.4. The number is higher among women (Table 3). The diseases that often coexist with comorbid diabetes and hypertension are heart diseases (0.17%), followed by goiter and thyroid (0.11%), joint pain (0.08%), bronchial asthma (0.05%), and gastric and peptic ulcer/acid reflux, and acute abdomen (0.05%) (Figure 2).

Table 1.

Percentage of Population Suffering from Multiple diseases in India.

Number of Diseases	Percentage of People Suffering from Multiple Diseases
Two diseases	4.1
Three and more diseases	1.0
Total	5.1

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Figure 1.

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Table 2.

Co-prevalence of Diabetes and Hypertension in India.

Percentage of population suffering from diabetes + Hypertension as percentage of total morbid population	2.06
Percentage of population suffering from diabetes + Hypertension as percentage of population having 2 diseases only	35.2
Percentage of population suffering from diabetes + Hypertension as percentage of population having more than 2 diseases	61.8

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Table 3.

Average Number of Diseases among the Comorbid (Diabetes + Hypertension) Population.

Male	2.3
Female	2.4
Total	2.4

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Table 4.

Co-prevalence of Diabetes and Hypertension by Socioeconomic Characteristics.

Socioeconomic Indicators	Percentage of Population Suffering from Comorbidity (%)
Sector
Rural	1.47
Urban	3.12
Gender
Male	1.96
Female	2.15
Social group
Scheduled tribes	0.64
Scheduled caste	0.62
Other backward classes	2.38
Others	2.70
Religion
Hinduism	1.41
Islam	1.41
Others	4.10
Education group
Not literate	1.34
Literate with no formal schooling	0.62
Up to elementary	2.37
Up to secondary	2.35
Graduation and above	3.59
Age group
15–24	0.00
25–34	0.02
35–44	0.42
45–59	2.95
60 and above	4.91
Economic status
First quintile	0.05
Second quintile	1.21
Third quintile	1.04
Fourth quintile	1.92
Fifth quintile	4.23
Primary activity status
Self employed	1.81
Worked as regular salaried/wage	2.58
Worked as casual/wage labour	2.55
Domestic duty and engaged in free sale of vegetables, tailoring, etc. for household use	2.24
Not working due to disability, pensioners, remittances recipient, and unemployed but seeking for job	6.73
Others including students	0.63

Source: Computed from unit-level data, NSSO 75 Round (2017–2018).

Figure 2.

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Socio-economic and Demographic Characteristics of the Co-morbid Population

It can be seen from Table 4 that out of the total morbid population in the urban sector, 3.12% are having coexisting diabetes and hypertension. In the rural population, the percentage of people suffering from coexisting diabetes and hypertension is 1.47%. The prevalence is 2.15% among women and 1.96% among men. People suffering from the comorbid condition are 0.64% in schedule tribes, 0.62% in schedule caste, 2.38% in other backward class, and 2.70% belonging to other categories. Its co-prevalence is higher among the other category, which is 4.10%, followed by Muslims (1.41%) and Hindus (1.41%). Among the illiterates, 1.34% are suffering from co-existing diabetes and hypertension. The percentage of people suffering from this health condition increases with education level. The highest prevalence rate is among those who are graduates and above (3.59%). The prevalence is higher among the aging population. It started to increase from 44 to 59 age groups (2.95%) and is highest among people who are 60 years and above. In the poorest quintile, that is, the first quintile prevalence is 0.05%, and it increases with every next quintile; 1.21% in the second quintile; 1.04% in the third quintile; 1.92% in the fourth quintile; and highest in the fifth quintile (4.23%). The prevalence is higher among those who are not working due to disability, have no work, and get pensions or remittances.

Predicators of Co-prevalence of Diabetes and Hypertension

As seen in Table 5, the marginal effect of comorbidity is significantly higher among the elderly aged 60 years and above, followed by the older adults age group of 45–59. In reference to their male counterparts, the co-prevalence of diabetes and hypertension is significantly higher among women. However, there are no significant rural-urban differences found in the co-prevalence of the diseases. In reference to scheduled tribes, the marginal effect of comorbidity is significantly higher among the other backward class (OBC). In reference to Hindus, people belonging to Islam and other category are significantly more impacted by comorbidity (0.3% and 0.4%). Education and comorbidity are positively associated. In reference to the poorest quintile, the marginal effect is significantly higher in all other quintiles, 0.53% in the first quintile, 0.74% in the second quintile, 1.33% in the fourth quintile, and 1.97% in the richest quintile (fifth quintile). People who are engaged in domestic duties and free sale of vegetables and those who are not able to work due to disability, pensioners, and remittance recipients are significantly at higher risk of comorbidity.

Table 5.

Predicators of Co-Prevalence of Diabetes and Hypertension.

Socio-economic and Demographic Characteristics	Marginal Effect (dydx)
Sector (Rural)
Urban	–0.000
Gender (Male)
Female	0.002*
Social Group (Scheduled Tribes)
Scheduled Castes	0.003
Other Backward Classes	0.007*
Others	0.003
Religion (Hind)
Islam	0.003*
Others	0.004*
Education Group (Not Literature)
Literate without formal schooling	0.002
Upto elementary	0.007*
Upto secondary	0.006*
Graduation and above	0.003*
Economic Status (1^st Quintile)
2nd Quintile	0.005*
3rd Quintile	0.007*
4th Quintile	0.013*
5th Quintile	0.019*
Age Group(15–24)
25–34	0.005
35–44	0.005*
45–59	0.24*
60 and above	0.04*
Primary activity status (Self-employed)
Worked as regular salaried/wage	0.006
Worked as casual/wage labour	0.001
Domestic duty and also engaged in free sale of vegetables, tailoring etc for household use	0.004*
Not working due to disability, pensioners, remittance recipients and unemployed but seeking for job	0.006*
Others including students	0.000

Source: Computed from Unit level data, NSSO 75 round (2017–2018).

Note: dy/dx for factor levels is the discrete change from the base level. *p < .05.

Treatment-Seeking Pattern

It can be seen from Figure 3 that among people suffering from comorbidity (diabetes + hypertension), 65.4% of them go to private hospitals and doctors for outpatient treatment, and 45.7% seek hospitalisation treatment. The important finding is that for hospitalisation, 34.6% of comorbid patients get treatment through others (including charitable hospitals/NGO and trust) and 2.78% use charitable hospitals and Ngo for outpatient treatment, which means that they cannot afford private/government hospitals or it is not available to them.

Figure 3.

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Economic Burden of Comorbidity

Diabetes and hypertension are long-term diseases that require regular medicines and check-up. Fail to do so can be fatal. Its treatment exerts huge healthcare costs and puts a financial burden on the households. Any additional disease in combination with coexisting diabetes and hypertension will put an additional financial burden on the household. As evident from Table 6, the combined average expenditure of diabetes and hypertension is ₹716.4. The average expenditure increases to ₹909.2 when other morbidities are associated with these two combinations. The average medical expenditure is ₹660 for coexisting diabetes and hypertension, and ₹909 when other morbidities are associated with these two combinations. The cost incurred on non-medical expenditure is ₹55.8. This cost rises to ₹74.4 along with other morbidities. The average medical cost incurred on hospitalisation due to diabetes and hypertension is ₹9,156.93. This cost rises to ₹13,012.5 when other morbidities are associated with diabetes and hypertension. Non-medical cost also increases from ₹1,730.6–₹1,997.4 with an increasing number of comorbidities (Table 7).

Table 6.

Health Expenditure Incurred on Treating the Ailment in Last 15 Days.

Expenditure Incurred on Diabetes + Hypertension Only			Expenditure Incurred on Diabetes + Hypertension along with Other Comorbidities
Medical Expenditure	Non-medical Expenditure	Total Expenditure	Medical Expenditure (Rs.)	Non-medical Expenditure (Rs.)	Total Expenditure
660.6	55.8	716.4	834.9	74.4	909.2

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Table 7.

Health Expenditure Incurred on Hospitalisation in Last 365 Days.

Expenditure Incurred on Diabetes + Hypertension			Expenditure Incurred on Diabetes + Hypertension along with Other Morbidities
Medical Expenditure	Non-medical Expenditure	Total Expenditure	Medical Expenditure (₹)	Non-medical Expenditure (₹)	Total Expenditure
9156.93	1730.6	10887.5	13012.5	1997.4	15009.9

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Since the study suggests that the highest share of the medical expenditure goes to medicine, we, therefore, looked at the share of different expenses to the total medical expenditure in the treatment of comorbidity (diabetes + hypertension). It is evident from Figure 4 that For treatment in the last 15 days (outpatient) medicine constitutes 83.2% of the total medical cost on coexisting diabetes and hypertension, followed by doctors and surgeon fees (6.8%), diagnostic (6.6%), and other medical expenses that include (3.5%). For treatment in the last 365 days (hospitalisation), medicine constitutes 45% of total medical expenditure followed by bed charges (19.1%), diagnostic (16.3%), doctors and surgeon fees (11.5%), and other medical expenses (8.1%).

Figure 4.

Source: Computed from Unit-Level data, NSSO 75 Round (2017−2018).

Discussion

The important findings of this study show that heart disease is the most common health condition found along with coexisting diabetes and hypertension, followed by goiter and thyroid, joint pain, bronchial asthma, and gastric peptic ulcer. Earlier studies have shown a high risk of cardiovascular diseases among diabetic and hypertensive patients (Promberger et al., 2013; Vijan, 2003). Although no clinical relationships could be determined by this data, the knowledge regarding the pattern of diseases can be helpful in informing the policymakers about the high-risk population so that efficient disease management and minimisation of complications could be addressed. A higher prevalence is witnessed among women. Some earlier studies have shown similar trends of women reporting higher prevalence (Violan et al., 2014). The social system in Indian society is such that women are overburdened, and they often keep themselves at low priority when it comes to their health and well-being. Moreover, biological and environmental factors could also be responsible for a higher prevalence among women (Ali et al., 2019). The higher prevalence among those attending domestic duties could be because of the higher prevalence among women as most of the domestic duties are performed by women. We also saw the prevalence of comorbidity among nonworking, disabled, and pensioners. It can be because of lack of physical activity, low immunity, and stress among the pensioners and disabled, and above all, most of them could be elderly or not working due to disability. Diabetes and hypertension could also increase the risk of disability that cannot be confirmed in this study.

This study establishes a positive association of comorbidity with economic status and education. The finding is inconsistent with the studies of developed nations, which discern an inverse relationship of comorbidity with economic status and education (Glover et al., 2004; Nagel et al., 2008; Salisbury et al., 2011). However, studies from developing countries like Bangladesh have shown a positive association between the two (Biswas et al., 2019; Tareque et al., 2015). The higher prevalence of comorbidity among the affluent and educated class can be because of a growing sedentary lifestyle, mental stress, work culture, and unhealthy dietary habits (Allen et al., 2017; Pandey et al., 2015). Other reasons could be the higher reporting and diagnosis of treatment among the richer and educated group.

Most patients with comorbidity go to the private hospital for both inpatient and outpatient treatment. This is due to the low quality of care in public hospitals, long waiting hours, and so on. Existing studies have demonstrated a positive association between comorbidity and higher out-of-pocket expenditure (Cortaredona & Ventelou, 2017; Lee et al., 2015). The current study also shows increasing medical and non-medical costs for both inpatient and outpatient treatment with comorbidities of diabetes and hypertension. The study shows that expenditure on medicine constitutes more than 80% of the medical cost for outpatient treatment and 45% for inpatient treatment, which is supported by other studies that have shown higher expenditure on medicines among patients with diabetes and hypertension (Eaddy et al., 2008). People suffering from diabetes and hypertension cannot go without medicines to be alive and it is a lifelong disease, so its consumption is for a lifetime. Moreover, existing comorbidities along with this combination result in more intakes of medicines.

Higher prevalence of comorbidity among the elderly population and in the states with an increasingly aging population such as Kerala, Andhra Pradesh, Himachal Pradesh, Tamil Nadu, West Bengal, and so on (Figure 5) call for an urgent policy intervention for setting up geriatric and integrated healthcare model for the management of coexisting diseases. Earlier studies have also shown higher prevalence among the elderly population (Banjare & Pradhan, 2014; Tripathy et al., 2017).

Figure 5.

Source: Computed from Unit-Level data, NSSO 75 Round (2017–2018).

Conclusion

Based on our result and conclusion, it can be concluded that comorbidity such as diabetes and hypertension is a major public health concern in a developing country like India because the healthcare system is single disease-oriented and is ill-equipped to deal with the complexities and management of coexisting health conditions (Lugtenberg et al., 2011; Tinetti et al., 2004). This issue is extremely relevant especially during the current ‘COVID-19’ pandemic due to the higher fatality and complications among COVID patients with comorbidity such as diabetes and hypertension (Banjare & Pradhan, 2014). In the current study, the self-reported co-prevalence of diabetes and hypertension is 2.06% which is lower than the study conducted by screening the India twin epidemic, which reported a prevalence of 20.6% (Joshi et al., 2012). Other studies have also reported a higher prevalence of up to 60% (Dhobi et al., 2008; Shah & Afzal, 2013). Symptoms of diabetes and hypertension are not well visible at their onset and often get undiagnosed and untreated (Anusuya et al., 2018; Deepa et al., 2003; Unnikrishnan et al., 2011). Therefore, there is a need for better screening, diagnosis, and public awareness programmes by the government so that a more realistic picture of this disease combination can be ascertained and the healthcare system can be prepared accordingly. The rising comorbidity of chronic diseases such as diabetes and hypertension should be given utmost priority keeping in mind the adverse outcomes associated with it. There should be more screening and diagnosis done by the government to understand the prevalence of these diseases in a better way. Population aging and a low level of awareness are the leading factors propagating this combination. Innovative and integrated chronic care models should be developed for better treatment of comorbid health conditions, and awareness should be spread at an early stage of life about the lethal outcomes of these diseases so that a healthy lifestyle can be followed from an early stage as these diseases are preventable.

Data Availability

NSSO Unit-Level data (75^th Round) was used for this study. The Unit-Level data is available in the text format at Ministry of statistics and program implementation (MOSPI), Government of India.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship and/or publication of this article: The authors acknowledge the support of ICSSR IMPRESS and Ministry of Education.

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