Pharmacological interventions for hypertensive emergencies : a Cochrane systematic review. Commentary

Hypertensive emergencies occur when high blood pressure is associated with the presence of acute end-organ damage, such as hypertensive encephalopathy. There is controversy as to when and which antihypertensive drugs to use in these situations. Using a comprehensive search strategy in electronic sources, MEDLINE, EMBASE and Cochrane clinical trial register, we conducted a systematic review to look all randomized control trials (RCTs) that compare an antihypertensive drug versus placebo, no treatment or another antihypertensive drug. Fifteen RCTs (representing 869 patients) met the inclusion criteria. Two trials included a placebo arm. All studies (except one) were open-label trials. Seven drug classes were evaluated in those trials: nitrates (nine trials), angiotensin-converting enzyme inhibitors (seven), diuretics (three), calcium channel blockers (six), α-1 adrenergic antagonists (four), direct vasodilators (two) and dopamine agonists (one). Mortality event data were reported in seven trials. Due to insufficient data, no meta-analysis was performed for clinical outcomes. Differences in blood pressure changes between antihypertensives were minor. There is no RCT evidence demonstrating that antihypertensive drugs reduce mortality or morbidity in patients with hypertensive emergencies. Furthermore, there is insufficient RCT evidence to determine which drug or drug class is most effective in reducing mortality and morbidity. There were some minor differences in the degree of blood pressure lowering when one class of antihypertensive drug is compared to another. However, the clinical significance is unknown. RCTs are needed to assess different drug classes to determine initial and longer-term mortality and morbidity outcomes.