Hypertension awareness, treatment, and control and their association with healthcare access in the middle-aged and older Indian population: A nationwide cohort study

Jinkook Lee, Jenny Wilkens, Erik Meijer, T. V. Sekher, David E. Bloom, Peifeng Hu

Abstract
Hypertension is the most important cardiovascular risk factor in India, and representative studies of middle-aged and older Indian adults have been lacking. Our objectives were to estimate the proportions of hypertensive adults who had been diagnosed, took antihypertensive medication, and achieved control in the middle-aged and older Indian population and to investigate the association between access to healthcare and hypertension management.

Introduction
Elevated blood pressure (BP), once a public health challenge largely affecting high-income countries, is now most prevalent in low- and middle-income countries [1]. India is home to 199 million adults with elevated BP [1], and hypertension is one of the most important drivers of the rising mortality and disability associated with cardiovascular diseases [2–4]. This growing impact of hypertension has drawn substantial research attention, generating many single-center studies and a few multicenter studies in the past 6 decades [5]. Anchala and colleagues [6] conducted a meta-analysis of these studies from 1950 to 2013, which was used as the scientific basis for the 2019 Indian Guidelines on Hypertension–IV [5,7], although the studies included in this meta-analysis generally represented the Indian population poorly [4].

Methods
We designed LASI as a nationally representative longitudinal study to provide detailed, comprehensive longitudinal data on the key health, economic, and social characteristics of India’s older adults. Using the 2011 census as the sampling frame, LASI represents the nation as a whole, as well as each state and union territory, with interviews of adults aged 45 years and older and their spouses of all ages. The prospective protocol of the project can be found in S1 Appendix. For the current analysis, we used the 2017–2019 baseline wave (N = 72,262) and the 2010 pilot wave (N = 1,683). Although much smaller in sample size, the 2010 pilot sample was recruited from 4 states, Karnataka, Kerala, Punjab, and Rajasthan, to represent the diversity of the country. Sampling weights were constructed and used in all descriptive analyses. The details of the study design have been described elsewhere [17,18]. The response rates for the 2017–2019 and 2010 waves were 87.3% and 90.9%, respectively.

Results
Table 1 presents the sample characteristics. The sample includes 59,433 adults aged 45 years and older in 2017–2019. The characteristics of the excluded sample can be found in S1 Table. The excluded sample includes a greater proportion of those aged 75 years and older, males, urban residents, and those with high socioeconomic status than the analysis sample (p < 0.01). We investigated the potential for selectivity bias in our estimates due to nonresponse by constructing a new set of weights for our baseline wave analysis sample: The results were very similar, usually within 1 percentage point, suggesting no evidence of selectivity bias (S2 Table). We also investigated the potential bias associated with imputation of missing values for per capita consumption by comparing distributions for the sample including the imputed cases with distributions for the sample that excludes them (S3 Table).

Discussion
Data from this nationally representative sample of adults aged 45 years and older in India indicate that slightly more than half (55.7%) of hypertensive individuals had been diagnosed, less than 2 in 5 (38.9%) took medication, and less than one-third (31.7%) achieved BP control. Therefore, the highest absolute losses to care occurred at the awareness stage (45.3 percentage points) and treatment stage (16.8 percentage points). This highlights a particular need for interventions that focus on awareness and treatment. Consistent with recent findings [28], we found substantial variation in hypertension management across socioeconomic groups, sexes, and geographic areas, calling for targeting of interventions for those currently lagging behind.

Citation: Lee J, Wilkens J, Meijer E, Sekher TV, Bloom DE, Hu P (2022) Hypertension awareness, treatment, and control and their association with healthcare access in the middle-aged and older Indian population: A nationwide cohort study. PLoS Med 19(1): e1003855. https://doi.org/10.1371/journal.pmed.1003855

Editor: Sanjay Basu, Harvard Medical School, UNITED STATES

Received: June 21, 2021; Accepted: October 26, 2021; Published: January 4, 2022

Copyright: © 2022 Lee et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: Data are held in a public repository (g2aging.org): https://doi.org/10.25549/h-lasi.

Funding: Data collection was funded by the National Institute on Aging, National Institutes of Health (NIA/NIH), U.S.A. (R01AG042778, DB, JL, TS, PH, EM, https://www.nia.nih.gov); the Ministry of Health and Family Welfare, Government of India (T22011/02/2015-NCD, TS, DB, JL https://www.mohfw.gov.in/); and the United Nations Population Fund (IND8U105/IIPSMU1D07, TS, DB, JL, https://www.unfpa.org). The NIA/NIH provided funding for a nationally representative sample, drawing samples from the 15 largest states. The Government of India provided additional funding to make the study representative of each state and union territory and enable oversampling of older adults and four metropolitan cities. The preparation of this paper was funded by the NIA/NIH, U.S.A. (2R01AG030153, JL, EM https://www.nia.nih.gov). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Abbreviations: AME, average marginal effect; BP, blood pressure; DBP, diastolic blood pressure; LASI, Longitudinal Aging Study in India; OR, odds ratio; PM-JAY, Pradhan Mantri Jan Arogya Yojana; SBP, systolic blood pressure

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