A prospective study of the physician effect on blood pressure in renal-transplant recipients

Physician presence results in elevated blood pressure (BP) in the general population. The determinants of this phenomenon in renal-transplant recipients are not known.

We prospectively evaluated BP changes with physician presence in 231 stable adults with graft survival > or =1 year. A nurse measured timed sitting BP by Korotkoff phase I and V sounds before physician entry, during physician presence and upon exit. The haemoglobin, creatinine, weight, immunosuppressive drug dosage and/or level, and anti-hypertensive medication profile were recorded. Paired Student's t-test with Bonferroni correction and multiple linear regression analysis were used to examine BP changes. Characteristics of patients with change in mean arterial BP > or =+10 mmHg (n=55, "high") were compared with those with change < or =+5 mmHg (n=132, "low") by chi-square or Wilcoxon rank sum test as appropriate. A group of 100 recipients served as controls in whom BP was measured thrice without physician presence on any occasion. A multivariate analysis was performed for the combined groups controlling for physician entry as a predictor variable.

In the study group, systolic BP (mean+/-SE) rose by 4.2+/-0.8, diastolic BP by 3.5+/-0.5 and mean arterial BP by 3.5+/-0.5 mmHg in physician presence. The BP returned to baseline with exit (P<0.001 for each). Higher haemoglobin and creatinine demonstrated a trend towards influencing the physician-induced rise in diastolic BP. The "high" sub-group demonstrated a shorter time to the second BP measurement in physician presence (P=0.03) and a trend towards morning measurements (P=0.08). In the control group, systolic BP declined by 3.2+/-0.9 mmHg from the first to the second measurement, with a further decline of 2.4+/-0.6 mmHg from the second to third measurements. Diastolic BP did not change. In the combined multivariate analysis, physician entry was an independent predictor of BP change (P=0.0001).

Renal-transplant recipients demonstrate a significant physician effect on BP despite adequate experience with post-transplant clinic visits and BP-altering medication. This population deserves further evaluation through ambulatory BP monitoring.