Nephrol Dial Transplant (2003) 18: 996-1000
© 2003 European Renal Association-European Dialysis and Transplant Association
A prospective study of the physician effect on blood pressure in renal-transplant recipients
Division of Nephrology, Department of Medicine, St Michael's Hospital, Toronto, Canada
Background. Physician presence results in elevated blood pressure (BP) in the general population. The determinants of this phenomenon in renal-transplant recipients are not known.
Methods. We prospectively evaluated BP changes with physician presence in 231 stable adults with graft survival 
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 +10 mmHg (n=55, ‘high’) were compared with those with change 
+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.
Results. 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).
Conclusions. 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.
Keywords: blood pressure; physician effect; post-transplant hypertension; white-coat effect; white-coat hypertension
Correspondence and offprint requests to: Dr G. V. Ramesh Prasad, Division of Nephrology, St Michael's Hospital, 61 Queen Street East, 9th Floor, Toronto, Ontario M5C 2T2, Canada. Email: prasadr{at}smh.toronto.on.ca