Figure 5:  .

AB/CD schema for optimisation of antihypertensive treatment. In choosing initial treatment—step 1—age in a white population is used as a surrogate for plasma renin, which falls with age. The typical younger patient (aged < 55 years) responds better to ACE inhibition or β blockade, whereas in the older patient (aged > 55 years) calcium channel blockade or diuretic is the preferred starting treatment; angiotensin receptor blockade can substitute for ACE inhibition in intolerant patients. Because the response of patients to the two drugs within each pair is well correlated, there is usually no point in switching an unresponsive patient to the other of the pair (for example, A to B); therefore step 2 in such a patient is to switch to one of the other pair. If the blood pressure is still above target, step 3 is to combine one drug from each pair.