Long-term blood pressure monitoring by office and 24-h ambulatory blood pressure in renal transplant patients: a longitudinal study.

Background: Renal transplant patients have a high prevalence of nocturnal hypertension, and hypertension misclassification by office blood pressure (BP) is quite common in these patients. The potential impact of hypertension misclassification by office BP on hypertension management in this population has never been analysed.

Methods: We performed a longitudinal study in a cohort of 260 clinically stable renal transplant patients. In all, 785 paired office and 24-h ambulatory blood pressure monitoring (24-hABPM) measurements over a median follow-up of 3.9 years were available in the whole cohort.

Results: A total of 74% of patients had nocturnal hypertension (>120/70 mmHg). Average office BP and 24-hABPM remained quite stable over follow-up, as did the prevalence of nocturnal hypertension, which was 77% at the last observation. However, the global agreement between office BP and average 24 h, daytime and night-time BP was unsatisfactory (k-statistics 0.10-0.26). In 193 visits (25% of all visits) where office BP indicated the need of antihypertensive therapy institution or modification (BP >140/90 mmHg), 24-hABPM was actually normal (<130/80 mmHg), while in 94 visits (12%), 24-hABPM was in the hypertensive range while office BP was normal. Overall, in 37% of visits, office BP provided misleading therapeutic indications.

Conclusions: Hypertension misclassification by office BP is a common phenomenon in stable renal transplant patients on long-term follow-up. Office BP may lead to inappropriate therapeutic decisions in over one-third of follow-up visits in these patients.