The Pressure Is On: Will Australia Adopt New Hypertension Guidelines?

The Evidence:

A randomised trial of intensive versus standard blood-pressure control

The Summary:

The SPRINT trial was a randomised, controlled trial comparing the safety and efficacy of intensive lowering of systolic blood pressure (SBP) to less than 120mmHg, compared with standard management to less than 140mmHg. The study included a total of 9361 patients,  who were eligible to participate if their age was greater than, or equal to, fifty years and had hypertension with a SBP greater than 130mmHg. Exclusion criteria included those patients with diabetes mellitus, previous stroke and/ or end stage renal disease.

The mean blood pressure in the intensive treatment group was 121.5/68.7mmHg and the mean number of medications required to maintain that SBP was 2.8. The mean blood pressure in the standard treatment group was 134.6/76.3mmHg, which required 1.8 medications.

Results of this study demonstrated that there was a lower risk of myocardial infarction, acute coronary syndrome, stroke, congestive heart failure or cardiovascular death in those patients with intensive blood pressure control, compared with standard blood pressure control (1.65% per year vs. 2.19% per year; hazard ratio with intensive treatment 0.75, P<0.001). Furthermore, all cause mortality was significantly lower in the patients with intensive blood pressure control, compared with standard blood pressure control (hazard ratio 0.73, P=0.03). The SPRINT trial also found that the rates of serious adverse events (hypotension, syncope, electrolyte abnormalities and acute kidney injuries) were significantly higher in the patients with intensive blood pressure control.

However, the SPRINT trial excluded those with Type 2 Diabetes Mellitus, making these results more challenging to generalise in a setting, such as the Torres Strait, where there is a large burden of diabetes. The Action to Control Cardiovascular Risk in Diabetes (ACCORD) Blood Pressure trial also compared standard blood pressure control (SBP less than 140mmHg) and intensive blood pressure control (SBP less than 120mmHg) in a diabetic cohort. Although this trial showed no benefit in intensive blood pressure control in cardiovascular disease outcomes, including stroke (hazard ratio 0.88, P=0.2), a more recent study, examining SPRINT-eligible participants of the ACCORD Blood Pressure trial, has demonstrated a reduction in cardiovascular disease outcomes with intensive blood pressure control.

The Recommendations:

As a result of the landmark SPRINT trial, the American Heart Association has tightened the diagnosis of hypertension from ≥140/90mmHg to ≥130/80mmHg for all adults. For those with Stage 1 hypertension and cardiovascular risk factors (i.e. previous stroke, ischaemic heart disease or cardiovascular risk ≥10%) these new guidelines recommend commencing an antihypertensive. For those with Stage 1 hypertension alone, the recommendation is lifestyle modifications. 

These dramatic changes in hypertension diagnosis has brought widespread debate with many clinicians expressing their concern that these new blood pressure guidelines may make millions anxious that there’re at risk of heart disease.  Furthermore many critics have highlighted that the side effects of taking antihypertensives may outweigh the benefits of more tightly controlling a patients’ hypertension. You can read the latest JAMA editorial on the benefits and harms of these new guidelines here.

The Australian Heart Foundation is yet to release any changes to their current hypertension guidelines. For the time being, blood pressure targets in Australia remain <140/90, however, this may change in time.

Further Reading:

American Heart Association Blood Pressure Guidelines 2017