[A single blood pressure reading during check-up for hypertension leads to a change in management more often than multiple readings].

Objective: To define the number of blood pressure readings necessary during a patient's visit to serve as a correct reference for patient management.

Design: Observational study.

Setting: Outpatient clinic in the Netherlands.

Method: In a period of 30 months blood pressure was measured in 250-300 patients with hypertension during 1008 patients' visits. All readings were done by the same physician in the same room with the same system, after the patients had been submitted to at least 10 minutes of supine rest. Three readings were taken simultaneously with a mercury sphygmomanometer and (via a Y-connector) with a semiautomatic oscillometric method.

Results: Blood pressure readings of 932 visits were available for further analysis. Both methods gave similar results for the mean of each reading and for the combination of 2 or 3 readings. Based on the first diastolic reading alone instead of the mean of 3 readings, 25% of the patients would have been subjected to different patient management. On the basis of the first two readings II% would have been treated differently.

Conclusion: No definite recommendation can be made for the ideal number of blood pressure readings per visit, but with only 1 or 2 readings, 11-25% of the subjects would have been submitted to different management.