Health inequalities research in India: a review of trends and themes in the literature since the 1990s

BACKGROUND Research on health inequalities can be instrumental in drawing attention to the health of socioeconomically vulnerable groups in India in the context of rapid economic growth. It can shape the dialogue for public health action, emphasizing the need for greater investments in health, and monitor effectiveness of health programs. Our objective was to examine trends in studies on health inequalities in the last 25 years. METHODS We conducted a systematic literature review of studies on health inequalities published from 1990. The year, 1990, marked the beginning of economic reforms and liberalization in India. We searched PubMED using key terms to identify 8800 articles between 1990 and 2016; we identified 1,312 final studies for review. Key domains of analysis included measures of equity, health outcomes, populations studied, year of publication, study methodology, study focus (descriptive versus analytical), and location of main author. RESULTS We found an increase in studies on health inequalities after 2005. About 88 % of the studies utilized quantitative methods for analysis. About 8 % of the studies related to health interventions or programs; the number of intervention studies have been increasing since 2010. A majority of studies were led by authors based in India. Early studies focused on mortality, communicable and non-communicable diseases, and nutrition, while later studies have focused on non-communicable diseases, mental health, risk factors, and injuries. Studies on women and children comprised nearly half of the literature; studies on the youth (15-24 years or as defined by the study) and elderly have been rising. Wealth and income were the most common measures of equity, followed by education and gender. The proportion of studies on wealth, education, region and caste have stayed consistent over time, while studies on gender disparities have been rising. CONCLUSION In a country as diverse as India with large social inequalities combined with rapid economic growth, research on health inequalities has a special significance for policy. We recommend that studies on health inequalities in the future focus on evaluations of policy and health programs, and on underrepresented health outcomes and populations.