The World Health Organization recently released guidelines for pharmacological treatment of hypertension. Though high blood pressure is a leading cause of disease, disability and death in all regions of the world, affecting an estimated 1.4 billion persons across the world, only 14% have it under control. This is because of three gaps in health system performance. Many who have hypertension are unaware, several of those who are detected are not on treatment and only half of those who are treated are effectively controlled on their prescribed treatment. If health systems do not improve their ability to detect and effectively treat hypertension, serious diseases of heart, brain, kidneys and blood vessels will mount.
Adopt healthy habits
All persons with raised blood pressure will need to adopt healthy living habits: reduced salt intake; consumption of more fruit and vegetables; avoidance or limited intake of alcohol; regular physical activity; maintenance of a healthy body weight; adequate water consumption, good sleep and stress reduction. In addition, several will need drugs for adequate control of blood pressure. The recent WHO guidelines, specifically addressing drug treatment, were framed by an international expert group chaired by me. Apart from assessing the strength of published scientific research, we also drew on the perspectives of policy makers, health system managers, healthcare providers, patients and communities.
While several international guidelines on management of hypertension do exist, many of them reflect the tertiary care perspective of high-income countries. Effective hypertension control must pivot on competent and continuous primary care, for both early detection and long-term management. Guidelines have also been divided over whether hypertension treatment should be initiated on the basis of blood pressure values alone or on a comprehensive risk assessment which takes into account age, gender, smoking status, body mass, prior cardiovascular disease, diabetes and blood cholesterol profile besides blood pressure values. While these measures are useful for customised future risk assessment, insistence on such detailed a priori assessment requiring various laboratory tests may delay initiation of treatment and increase loss to follow-up in primary care. Guidelines must maximise benefits and minimise harm and inconvenience to patients.
The benefit of drug treatment was assessed on health outcomes which included the following: blood pressure control, deaths from any cause, cardiovascular mortality, heart attacks, brain strokes, heart failure and advanced kidney disease. Recommendations were graded on the strength of evidence available and distilled with health system perspectives on feasibility of implementation. The aim was to develop evidence-informed, situationally adaptable, resource-optimising, operationally steerable and equity-promoting guidelines which can be implemented in all countries despite varying health system capacities.
Suggested thresholds
Initiation was recommended for all adults whose blood pressure readings, reliably measured, exceed 140 mm of mercury for the upper level (systolic) or above 90 mm for the lower level (diastolic). However, for persons with a prior history of cardiovascular disease, diabetes or chronic kidney disease, treatment should be initiated if the systolic pressure exceeds 130 mm. The same threshold is advised for persons with a high future risk of developing cardiovascular disease, based on clinical and laboratory assessment. Laboratory tests should be performed at the time of diagnosis of hypertension. However, if testing facilities are not readily available and tests are likely to be delayed, treatment may be initiated with a single relatively safe drug amlodipine (a long acting calcium channel blocker) and tests may then be ordered. When test results are available, they will help with choice of further treatments and in comprehensive risk assessment.
When tests confirm that there are no contraindications to certain drugs, three classes of drugs are offered to the prescribing physician on the strength of evidence. They are: thiazide diuretics and thiazide-like agents; angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (both of which act at different levels of the renin–angiotensin system) and calcium channel blockers. Better clinical outcomes are achieved in most persons when drugs from any two of these categories are initially used in combination, in moderate doses, rather than using a single drug in a high dose. This provides the advantage of combining two different but complementary modes of action and avoids the side-effects that accompany a high dose of any single drug.
Recommended targets
The target is to lower blood pressure values to less than 140/90 mm, in all adults. In persons with known cardiovascular disease, the target is a systolic value less than 130 mm. This is based on strong evidence. The same target is also recommended for persons at a high risk of cardiovascular disease or with co-existing diabetes or chronic kidney disease. Persons in whom treatment has been initiated should be followed up monthly, till the target level has been achieved. Once that has been reached, follow up may be once in three to six months, as feasible.
It has been recommended that non-physicians like nurses and pharmacists can provide drug treatment for hypertension if they receive proper training, have prescribing authority, follow specific management protocols and have physician oversight. Community health workers may assist in patient education, blood pressure measurement and delivery of medications, as part of a health team. Telemonitoring and home or community-based self-care are encouraged to improve blood pressure control, as part of an integrated management system.
These guidelines are positioned within a strong scientific frame of evidence, while accommodating the practical aspects of implementation across diverse health systems. Low- and middle-income countries, which have the highest health burdens resulting from uncontrolled hypertension, should find it easier to implement these guidelines rather than those tailor-made for high-income countries.
(Prof. K. Srinath Reddy, a cardiologist and epidemiologist, is President, Public Health Foundation of India ,. Views expressed are personal.)
