PP088. Oral antihypertensive therapy for severe hypertension in pregnancy

The hypertensive disorders of pregnancy are among the leading causes of maternal mortality and morbidity. The vast majority occurs in low and middle income countries. It is widely accepted that women with severe hypertension are at increased risk of stroke and benefit from blood pressure (BP) reduction. Although traditionally, parenteral antihypertensive agents have been studied for treatment of severe hypertension in pregnancy, oral agents would be ideal for use in the community and in under-resourced settings.

To review the published evidence for the effectiveness of oral antihypertensive therapy for severe hypertension in pregnancy.

The following databases were searched (to May/11) for randomised controlled trials (RCT) of oral antihypertensive therapy for severe hypertension in pregnancy: MEDLINE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Database of Abstracts of Reviews. Inclusion criteria were: severe hypertension [an inclusion criterion or average enrollment BP of: systolic BP ⩾160mmHg and/or diastolic BP ⩾110mmHg), use of oral or sublingual antihypertensive therapy in at least one of the treatment arms, and at least one relevant measure of maternal or perinatal outcome within a week of administration. Data were abstracted independently by two reviewers and discrepancies resolved by consensus. The Cochrane Revman 5.1 software was used for statistical analysis according to standardised methodology.

We identified 14 eligible trials (796 women). Most compared oral/sublingual (SL) nifedipine 5-10mg (10 trials, 606 women, 8/10 trials specified capsule preparation), with either: intravenous (iv) hydralazine 5-20mg (6 trials, 282 women), oral nifedipine 10mg PA tablets (1 trial), oral prazosin 1mg (1 trial), iv labetalol (1 trial), or iv/intramuscular (im) chlorpromazine 12.5 (1 trial). Three trials (154 women) compared oral methyldopa (250-500mg initially) with either oral labetalol (100mg), atenolol (50-200mg) or kentanserin (80-120mg) (1 trial each). One trial (36 women) compared SL isosorbide 1.25mg with iv magnesium sulphate (4g iv then 1g/hr). No trials were identified that compared oral labetalol with either parenteral hydralazine or oral nifedipine. Nifedipine compared favourably with parenteral hydralazine with no differences seen in BP control or maternal or perinatal outcomes. Heterogeneity between trial results was seen within the oral/SL nifedipine vs. iv hydralazine subgroup in which one trial evaluated treatment success and side effects over 20min, and found that nifedipine was associated with relatively lower success and fewer side effects. The incidence of maternal hypotension in the nifedipine capsule arms of these trials was low (1/102, 3 trials), but hypotension was common in both arms of a trial of nifedipine 10mg capsule vs. 10mg PA tablet trial (i.e., 11/31 vs. 3/33, risk difference 26%, 95% CI7% to 46%).

Given the available RCT data on which to base oral antihypertensive treatment of severe hypertension in pregnancy, the choice of antihypertensive agent may need to be driven by the availability of the drug, setting in which it is to be administered, and by whom. For facility use, the evidence supports oral nifedipine capsules.