Prevalence of hypertension and its risk factors among cotton textile workers in low- and middle-income countries: a protocol for a systematic review

Globally, hypertension (HTN) is identified as one of the leading causes of mortality and disability [1]. It has led to 7.5 million deaths and accounted for 57 million disability-adjusted life years (DALYs) or 3.7% of total DALYs [2]. Hypertension is characterized as a constant rise of systolic blood pressure and/or diastolic blood pressure of more than or equivalent to 140 mmHg and/or 90 mmHg respectively [3]. Currently, around 1.13 billion individuals are suffering from hypertension globally and two-third of them resides in low- and middle-income countries (LMICs) [4] while LMICs’ selection is based on World Bank’s (WB) 2018 Country Classification list, having GNI per capita between $996 and $3895 [5]. The number of hypertensive people is projected to grow by 70 million individual from 2000 to 2025 in high-income countries (HIC) while it is estimated to grow by > 500 million in LMICs over the same period [6]. A systematic review included data on 1,494,609 adults from 45 countries also showed that there is the highest burden of hypertension (32%) in LMICs and prevalence estimates were found to be higher in elders, overweight/obese, urban settlers, and having informal education [7]. Moreover, worldwide high blood pressure is one of the major risk factors for cardiovascular diseases (CVD) that refers to diseases of the heart and blood vessels [8, 9], stroke, coronary artery disease, and peripheral vascular disease [9]. The burden of CVD across the world is very high and in LMICs, 47% of mortality secondary to CVDs and 44% of CVDs’ burden are attributable to HTN/high blood pressure (BP) [9, 10]. Generally, it is asymptomatic and the primary presentation can be seen with a devastating event like stroke or heart disease [11]. It is estimated that 45% of deaths with heart disease and 51% of deaths with stroke are related to hypertension [12]. This is the reason that it is referred to as the “silent killer” [11].

Worldwide, the textile industry has more than 60 million employees [13] who are involved in the production of fibers, yarns, fabrics, clothing, and textile products for domestic and decoration, along with the technical and industrial purposes [14]. Moreover, the textile industry involves a cluster of related industries that utilize a range of natural fibers (cotton, wool, silk, etc.) and/or synthetic fibers to generate fabric [15] which eventually produces varying amounts of dust [16]. Workers are exposed to various hazards in textile industry that might result in different ailments [17, 18]. Studies reveal high level of oxidative stress in cotton textile workers [19] leading to the development of essential hypertension [20, 21]. A study conducted in Kannur district in India found out that the prevalence of hypertension was 22.3% among cotton textile workers which was equivalent to the prevalence of general population [22]. Furthermore, increasing age, alcohol consumption, family history of hypertension, BMI > 25 kg/m², and high waist-hip ratio were identified as a strong factor of hypertension among cotton workers [22]. Similarly, a study conducted in Dhaka, Bangladesh, notified that both general and central obesity were found to be significantly associated with hypertension [23]. Additionally, factors such as work-related stress, noise pollution, lack of earplug usage, tobacco smoking, and long duration of employment contribute towards the development of hypertension among the cotton textile workers [22, 24‐27]. While stress in job also has a negative impact on worker’s cardiovascular health which in turn will affect their job performance [28]. However, the association between cotton dust and increased blood pressure may not be strong, as confounding factors and bias impact could not be excluded [18, 29].

Chronic diseases make workers less productive, more prone to injury that leads to significant suffering, and add huge financial and service challenges on health care systems [23, 30‐32]. Furthermore, it is witnessed that collective monetary losses related with the hypertension and diabetes mellitus (DM) in low- and middle-income countries are estimated to be over $7 trillion during the years 2011–2025 that move millions of individuals below the poverty line [33]. Hypertension accounts for the global burden of cardiovascular disease which evidently has huge impact on individuals, organizations, and country in terms of economy [11]. Therefore, early detection of hypertension by identifying its risk factors is essential among high-risk population particularly in LMIC. Thus, the objective of this study will be to evaluate the prevalence of hypertension and its risk factors among adult cotton textile workers in low- and middle-income countries.

The present protocol has been registered within the PROSPERO database (registration ID: CRD42020167175). The present study protocol is being reported in accordance with the reporting guidance provided in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement [34] (see PRISMA-P checklist in Additional file 1).

This review will highlight the proportion of hypertension along with its risk factor among cotton textile workers in LMICs. Given that, some of the modifiable factors may be prevented in this high-risk population, we will call on health experts including policy makers, stakeholders, cardiovascular epidemiologist, and occupational health and safety specialists to prioritize policies and commission and conduct screening and awareness programs to improve worker’s health. Besides, this review will highlight an urgent need for further research on hypertension in cotton textile workers that fill in some of the data gaps such as the trends and determinants of hypertension. The review findings will be made publicly available. The results of the review will be disseminated through peer-reviewed publications and presenting at professional conferences either in the form of oral or poster presentations. Any amendments made to this protocol when conducting the study will be outlined and reported in the final manuscript.