Managing hypertension in primary care
Dr Paul Chiam, a senior consultant cardiologist at The Heart & Vascular Centre, Mount Elizabeth Hospital, Singapore, and an Adjunct Associate Professor at the National University of Singapore, shares his insights with Pearl Toh on diagnosing and managing hypertension in the primary care setting.
Hypertension is one of the commonest chronic conditions with a prevalence as high as 25 percent in adults over 18 years of age. The prevalence of hypertension increases with age over 40 years, with more than half of the elderly aged >60 years having hypertension. With an ageing population, this will pose a continuing challenge in the prevention and control of hypertension
Unfortunately, hypertension does not cause any symptom – it is therefore a ‘silent killer’. If left untreated, hypertension can lead to complications such as stroke, heart failure, other cardiovascular diseases, and kidney failure.
The conventional method for diagnosing hypertension is through blood pressure (BP) measurement in the clinic. For accuracy, patients should be rested in a quiet room for at least 5 minutes before BP is taken. Taking the average of ≥2 readings would also help to improve the accuracy of BP readings. If the first two readings vary by ≥5 mm Hg, further readings should be taken and averaged. Ensuring that the BP cuff fits nicely (not too tight, but also not too loose) on the patient’s arm is also important. [J Am Coll Cardiol 2018;71:e127-e248; Singapore Med J 2018;59:17-27]
In addition, out-of-office or home BP readings can be used to assess hypertension. This may help avoid “white-coat hypertension” (whereby clinic BP is high, but home BP is normal) or reveal “masked hypertension” (whereby clinic BP is normal, but home BP is high). If there is any doubt, a 24-hour BP recording (ambulatory BP) can be performed to obtain a 24-hour average BP.
There have been a lot of debates on the recommended BP threshold for hypertension diagnosis. To treat the entire population to a BP below 130/80 mm Hg, as recommended by the ACC/AHA 2017 guidelines, will entail increased costs, significant increase in drug side effects, and very marginal health benefits in many patients. Currently, the Singapore Ministry of Health maintains a BP threshold of
≥140/90 mm Hg for hypertension diagnosis. [Table 1. MOH Clinical Practice Guidelines 1/2017 Hypertension Executive Summary;
Singapore Med J 2018;59:17-27]
The key aim for managing hypertension is to control the BP to a level ideal for the particular patient, taking into account his/her age and other risk factors for cardiovascular disease. This will help to tailor a treatment strategy suited to the patient and reduce the risk of long-term complications.
We should always start with lifestyle modification: moderate exercise and a reduction in salt (sodium) intake. Reducing stress and getting sufficient sleep will also help. For most of the patients with high-normal BP between 130/85–139/89 mm Hg, lifestyle changes may be enough to control and lower their BP. We should give a period of 2–3 months for patients to try lifestyle modifications and then review their BP control. Medications should be started if the BP is still high after a good attempt at lifestyle changes.
The three main groups of drugs used for treatment include: calcium channel blockers, ACE inhibitors/ ACE receptor blockers, and a thiazide diuretic. These are the first-line drugs for treatment (any one can be used to initiate therapy). A beta-blocker can be added if further control is required (second line). Other less commonly used drugs include prazosin, hydralazine, etc.
When the patient’s BP cannot be controlled despite two or three classes of medications or if end organ damage occurs due to hypertension, referral to a cardiologist or a hypertension specialist should be considered. Signs that may be suggestive of end organ failure include increased breathlessness on exertion or breathlessness at rest (heart failure), sudden onset of weakness of numbness usually involving one side of the body (stroke), sudden severe headache (stroke), or general lethargy/ frothy urine/ reduced urine output (kidney failure).
The other group that may require a specialist referral are the very young hypertensives (<30 years old) or those with suspected secondary hypertension. However, the majority of patients can usually be well managed by GPs and only very few will require specialist referral.
Patient’s noncompliance to recommended management strategies (lifestyle changes and/or medications) is one of the challenges a physician may face. Refusal to intensify treatment despite suboptimal BP control and ignorance on the urgency of condition, for example, patients who try to down play the diagnosis by attributing their high BP reading to external factors (not sleeping well, just walked into the clinic) can also impede effective management of patients.
Therefore, it is important for GPs to engage their patients in meaningful discussion so that the patients understand why hypertension is harmful even though they “don’t feel anything” and the consequences of leaving their condition uncontrolled.
For patients resistant to treatment intensification but in whom this step is indicated, GPs play important role in educating the patients that medications can reduce further increase in BP (and interrupt the vicious cycle of ever increasing BP) as well as prevent complications, in particular, stroke. Finding out the cause of the patient’s resistance can often help, for example, a fear of side effects from medication. In this case, letting them understand that serious side effects with modern BP medications are very uncommon and side effects, if any, are usually benign and manageable may encourage patients to be more receptive to treatments.
The first step is to confirm the diagnosis – this may require multiple measurements including home BP recordings or a 24-hour ambulatory BP monitor. This is because treatment is usually lifelong. Once diagnosed, it is reasonable to give a period for a trial of lifestyle modification. After that, medications can be commenced.