The placebo effect and white coat effect in isolated systolic hypertensionand systo-diastolic hypertension

It is well recognised from many clinical trials that there is a blood press ure lowering effect when placebo is administered to patients with essential hypertension ("placebo effect"). The reduction in blood pressure, however, may also be partly due to loss of the alerting response ("white coat effec t") as a result of familiarisation with the clinical environment. To invest igate the hypothesis that then may be a more marked placebo effect and whit e coat effect in isolated systolic hypertension (ISH) compared with systodi astolic hypertension (SDH), we studied 78 patients with hypertension: 34 ha d ISH and 44 patients had SDH. The 34 patients with ISH were older (68.7 vs 54.9 years), had a higher SEP (192.2 vs 169.6 mmHg) and lower DBP (85.5 vs 102.0 mmHg) when compared to patients with SDH. Amongst the patients with ISH, there were no significant changes in mean blood pressures pre-placebo (paired t-test, p = NS). In the placebo period, there was a significant red uction in systolic blood pressures at all three points, and a significant r eduction in diastolic blood pressures after 2 and 3 months placebo (paired t-test, p < 0.05). There was a mean reduction in mean systolic blood pressu re at visit 1 by 5.2%, visit 2 by 5.1% and visit 3 by 4.6%, when compared t o mean pre-placebo systolic blood pressures (p < 0.05). The mean reduction in diastolic blood pressure was 5.8% at visit 2 and 3.5% at visit 3, when c ompared to mean pre-placebo diastolic blood pressure (p < 0.05). At the 4-w eek visit after receiving placebo, the mean systolic blood pressure decreas ed by 9.4 mmHg (p = 0.003) and mean diastolic blood pressure by 2.7 mmHg (p = NS) in the patients with ISH. In patients with SDH, there were no statis tically significant changes in recorded BP readings following the introduct ion of placebo. We suggest blood pressures in some patients with ISH may se ttle with careful follow up and initiation of treatment in these patients c ould potentially be delayed for at least 3 months, as therapy may not prove necessary.