WHITE-COAT EFFECT ON BLOOD PRESSURE MEASUREMENT AMONG VISITING PATIENTS TO SHIRAZ UNIVERSITY INTERNAL CLINIC

High blood pressure (HBP) is the commonest referred reason for visiting clinics from which 25% of all population suffer at some stage of their lives. The “white coat hypertension” has been implicated as one of the difficulties in diagnosis and treatment of HBP and can predispose the patients to unnecessary drug treatments. On the other hand, the incidence rate of this phenomenon among different societies varies. This study attempts to clarify its incidence among Iranian population.One hundred subjects, having the allocated criteria (29 male, 71 females, age range 32-81 years old) were randomly selected for this quasi-experimental study. The patients were selected from those visiting the internal clinic of Shiraz University and who suffered from HBP or those diagnosed for the first time. The blood pressure was measured twice by the attending physician and then by a nurse (a member of the research team), who made the home visit measurements, using the same mercury gauged instrument. Fifteen percent of the patients were those who were diagnosed to have HBP for the first time and the remaining were already on drug treatment. The results showed that there was significant difference between in the measurement of both systolic and diastolic blood pressures in the clinic and at home among the patient who were already under drug treatment for their HBP (P<0.001 and < 0.01 respectively). While there was a significant difference only in the systolic blood pressure among the first-time diagnosed patients (P <0.001). Overall result showed there was an increase of 20 mmHg in the systolic blood pressure among 36 % of the patients (systolic white coat effect). While the corresponding increase in the diastolic blood pressure was 10 mmHg in 43 % of the patients (diastolic white coat effect).This study demonstrated that there was a significant white coat effect on a high percentage of the patients who visit the clinics for blood pressure assessment, and these findings need to be considered when attempting to prescribe or change drugs regiments. The visiting nurse can ameliorate these discrepancies.