Review question
What effects do the different ways of screening for hypertension (mass, targeted, or opportunistic) have in decreasing illness and death?
Background
Hypertension is a long-term non-communicable disease (NCD), also known as high, raised, or elevated blood pressure. Blood pressure is expressed by two measurements (systolic (SBP) and diastolic (DBP) pressures), which are the maximum and minimum pressures. High blood pressure is generally diagnosed when resting blood pressure is persistently at SBP ≥ 130/140 millimetres mercury (mmHg) or at DBP ≥ 80/90 mmHg for adults.
Even though blood pressure in the arteries is continuously raised, in many cases, high blood pressure does not cause symptoms. Nonetheless, hypertension can increase the risk for heart failure, stroke, vision loss, and chronic kidney disease, and so on, in the long term. People who have unhealthy diets, consume harmful amounts of alcohol and/or tobacco, and are physically inactive are at higher risk of hypertension.
Early detection, adequate treatment, and good control of high blood pressure can lower the risk of complications associated with hypertension. Although early detection through screening of hypertension has the potential to contain health-related costs, reducing the burden of hypertension will to some extent involve addressing behavioural and socioeconomic risk factors (such as income, occupation, and level of education). Therefore, it is unclear whether early detection of mild hypertension can positively impact health-related costs in the long term and improve health outcomes by reducing the need for hospitalisation and management of hypertension-related complications, which can be severe.
Review methods
We searched various electronic databases on this topic until 9 April 2020. We searched for studies written in any language, whether published or not. We planned to include studies that compared one type of screening strategy for hypertension versus no screening strategy, that is, mass screening versus no screening, targeted screening versus no screening, and opportunistic screening versus no screening. We were interested in studies in which participants were healthy adolescents, adults, and elderly people, and in which researchers measured clinical outcomes, health system outcomes, and adverse events.
Key results
We found no studies that met the criteria described above.
Quality of the evidence
High-certainty evidence that can tell us whether mass, targeted, or opportunistic screening strategies are effective for reducing illness and death associated with hypertension is lacking.
There is an implicit assumption that early detection of hypertension through screening can reduce the burden of morbidity and mortality, but this assumption has not been tested in rigorous research studies. High-quality evidence from RCTs or programmatic evidence from NRCTs on the effectiveness and costs or harms of different screening strategies for hypertension (mass, targeted, or opportunistic) to reduce hypertension-related morbidity and mortality is lacking.
Hypertension is a major public health challenge affecting more than one billion people worldwide; it disproportionately affects populations in low- and middle-income countries (LMICs), where health systems are generally weak. The increasing prevalence of hypertension is associated with population growth, ageing, genetic factors, and behavioural risk factors, such as excessive salt and fat consumption, physical inactivity, being overweight and obese, harmful alcohol consumption, and poor management of stress. Over the long term, hypertension leads to risk for cardiovascular events, such as heart disease, stroke, kidney failure, disability, and premature mortality.
Cardiovascular events can be preventable when high-risk populations are targeted, for example, through population-wide screening strategies. When available resources are limited, taking a total risk approach whereby several risk factors of hypertension are taken into consideration (e.g. age, gender, lifestyle factors, diabetes, blood cholesterol) can enable more accurate targeting of high-risk groups. Targeting of high-risk groups can help reduce costs in that resources are not spent on the entire population.
Early detection in the form of screening for hypertension (and associated risk factors) can help identify high-risk groups, which can result in timely treatment and management of risk factors. Ultimately, early detection can help reduce morbidity and mortality linked to it and can help contain health-related costs, for example, those associated with hospitalisation due to severe illness and poorly managed risk factors and comorbidities.
To assess the effectiveness of different screening strategies for hypertension (mass, targeted, or opportunistic) to reduce morbidity and mortality associated with hypertension.
An Information Specialist searched the Cochrane Register of Studies (CRS-Web), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Latin American Caribbean Health Sciences Literature (LILACS) Bireme, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) without language, publication year, or publication status restrictions. The searches were conducted from inception until 9 April 2020.
Randomised controlled trials (RCTs) and non-RCTs (NRCTs), that is, controlled before and after (CBA), interrupted time series (ITS), and prospective analytic cohort studies of healthy adolescents, adults, and elderly people participating in mass, targeted, or opportunistic screening of hypertension.
Screening of all retrieved studies was done in Covidence. A team of reviewers, in pairs, independently assessed titles and abstracts of identified studies and acquired full texts for studies that were potentially eligible. Studies were deemed to be eligible for full-text screening if two review authors agreed, or if consensus was reached through discussion with a third review author. It was planned that at least two review authors would independently extract data from included studies, assess risk of bias using pre-specified Cochrane criteria, and conduct a meta-analysis of sufficiently similar studies or present a narrative synthesis of the results.
We screened 9335 titles and abstracts. We identified 54 potentially eligible studies for full-text screening. However, no studies met the eligibility criteria.