A hospital-based study of socioeconomic status and clinical spectrum of rheumatic heart disease patients of Assam,North-East India

Background

Rheumatic heart disease (RHD) is one of the most common acquired heart diseases causing permanent damage to heart valves which ultimately leads to heart failure. Statistical data shows approximately 33,194,900 patients with RHD throughout the countries where RHD is endemic and 221,600 cases in countries where it is not endemic. ¹ It is a notable cause of morbidity and mortality in India, with approximately 13.17 million RHD patients. ¹ In the North-East region of India, no exact prevalence data is available but some reports have indicated high prevalence in this region.^2,3

Persistence of RHD in developing nations and reemergence in some of the developed nations emphasizes the role of socioeconomic status (SES) in sustainability of RHD. Furthermore, SES and psychosocial factors play an important role in the prevalence and pathophysiology of cardiovascular diseases.^4–6 A significant association between SES and prevalence of RHD has been well documented by a number of investigations. Persistence of low socioeconomic factors such as overcrowding, illiteracy, poor nutrition, lack of education in the mother, maternal unemployment, poor quality housing and distance from public health centers was found to be associated with increased risk of RHD in different parts of the world.^7–9

In India, high prevalence of RHD has been associated with low SES of the people in Srinagar and Bikaner.^10,11 Another study, of schoolchildren from urban and rural areas of Shimla, reported a decline in RHD during a span of 15 years due to improved socioeconomic conditions and easy health care access. ¹² Also, the majority of low-SES populations have available only inadequate preventive services and only a few patients receive early cardiac interventions, which increases the likelihood of patients progressing towards the chronic form of the disease. Overall, these studies confirm the role of low SES in increased prevalence of RHD in different regions of India. In North-East India, there is a lack of data to confirm the role of SES in increased prevalence and clinical complications of RHD.

Aim

The objective of this study was to investigate the plausible association between SES and increased risk of RHD and its clinical profile in different groups within the population of Assam, North-East India. To the best of our knowledge, this is the first study to document the association between SES and increased risk of RHD in Assam, North-East India.

Methods

A hospital-based case–control study was designed in which RHD cases with age- and sex-matched healthy controls were investigated and cases were selected on the basis of admission in Assam medical college and hospital in Dibrugarh, Assam. Various parameters of SES were chosen on the basis of previous literature surveys.^7,8 Parameters included in the questionnaire were: status of education, employment, monthly income, overcrowding, clinical details and other measures of SES. Data was collected by direct interview of the patients by a research assistant under the supervision of a doctor in the department of cardiology.

Ethical approval to conduct this study was obtained from Assam medical college and hospital, Dibrugarh (AMC/IEC/H/11786). All the participants or their family members (in the case of patients below 18 years old) were given an explanation of the study in their local language and received the written consent document.

Cases aged 9–67 years were included in the study and were defined as RHD patients on the basis of previous rheumatic fever (RF) history, clinical examination and confirmed diagnosis by echocardiography. Clinical examination was performed by cardiologists with experience in the diagnosis of RHD. Clinical diagnosis and confirmation of RHD was done according to World Heart Federation criteria for echocardiographic diagnosis of RHD ¹³ for inclusion of RHD cases.

All the participants of North-East Indian ethnic origin were included in the study. Patients with a history of valvular heart surgery and pregnant females were excluded from the study. Controls had normal echocardiograms with no previous history of RF/RHD and no major disease. Patients who did not give consent were also excluded from the study.

Statistical analysis was carried out using GraphPad PRISM (version 5) software. Odds ratio (OR) and p value at 95% confidence interval (CI) were calculated.

Results

Patients were categorized on the basis of their ethnic groups. The majority of patients were from Ahom (22%), Tea-Tribe (18%), Kachari (11%), Assamese (10%), Brahmin (10%) and Kalita (10%).

Dwelling location (p < 0.0001, OR=4.1, 95% CI = 2.29−7.45), monthly income (p < 0.0001, OR=9.5, 95% CI = 4.99−18.1) and education (p < 0.005, OR=9.5, 95% CI = 1−8.66) were found to be statistically significant and are associated with increased risk of RHD, whereas overcrowding, housing type and type of fuel used (wood or cooking fuel) for cooking did not reach statistical significance. In most of the families, two people were sharing a room and in some families more than two people were sharing a single room but ample size and ventilation of the room might explain no impact of overcrowding on the disease. However, most of the female patients used wood for cooking but proper ventilation of the houses might have excluded the probability of contribution of smoke or congestion in increased risk of RF/RHD. Also, more than 50% of patients’ parents were illiterate and the majority of patients were engaged in low-income occupations such as tea garden working and farming.

As far as the clinical profile of patients is concerned, more than 80% of patients had easy fatigability followed by palpitation and 45% and 60% of the patients had paroxysmal nocturnal dyspnea and dyspnea, respectively. Presence of the combination of two or more symptoms was less frequent in most of the patients. Carditis (20%) is the most predominant manifestation followed by arthralgia (14%) and migratory polyarthritis (14%). Of the RHD patients, 28%, 9% and 8% were diagnosed with mitral stenosis, mitral regurgitation and atrial regurgitation, respectively, and 77% of mitral stenosis, 53.3% of mitral regurgitation and 41% of atrial regurgitation cases were severe. Out of the severe cases, 23% of mitral stenosis, 7% of mitral regurgitation and 2% of atrial regurgitation lived in a rural location.

Mitral and aortic valve thickening were found in 57% and 22% of patients, respectively, and 33% of patients had dual involement of mitral and aortic valve. Mitral regurgitation was found to be slightly predominant in females (46.5%) whereas atrial regurgitation was more common in males (56.4%). Dental caries and missing teth were observed in 47% and 30% of patients, respectively and 62.8% of patients were not even aware of the importance of oral health hygiene.

Conclusion

Even though only few studies have been done so far to investigate RHD in the North-East Indian population, the data available indicates a high prevalence of RHD in this region. In this study, results seem to clarify the impact of socio-economic risk factors in RHD patients of Assam. Our study confirmed the significant role of education, monthly income and dwelling location in RHD. Some parameters (e.g. cooking fuel) did not reach statistical significance but an increasing trend towards RHD has been observed. The existing disease burden of RHD and its debilitating clinical scenario is more prevalent in low SES populations. Further detailed case–control-based investigations are required to establish a well-documented role of socio-economic factors in RHD patients of Assam and other regions of North-East India.

Taken together, the cumulative effect of socioeconomic disparities might augment the predominance of RHD in Assam, North-East India and it might also be associated with the progression of the disease. Precise recognition of the role of socioeconomic factors can ensure early interventions in the vulnerable population and upgradation of SES might influence the prevalence of RHD.