Objective: To determine prevalence of hypertensive (HT) patients whose BP can be normalized (hospital BP <140/90 mmHg) for at least a year and still remained normotensive (NT) after 12-week anti-HT drug withdrawal. Clinical characteristics of
this group of patients were assessed.
Material and Method: At least a year of well controlled HT patients by hospital BP without target organ damage and diabetes mellitus who were treated with single low-to-standard dose anti-HT medication in hypertension clinic, Siriraj Hospital were screened. After an informed consent was signed, epidemiologic data, cardiovascular risks and laboratory data done within a year was collected. The anti-HT drug taken would be discontinued and a series of home blood pressure (HBP) was
measured twice a day (wake-up time and bed time) for 2 weeks. The anti-HT drug was still discontinued in normal HBP group
(average HBP <135/85 mmHg) and reassessed hospital BP 10 weeks later (week 12). Previous anti-HT medications were resumed in high HBP group (average HBP >135/85 mmHg), at week 2. At week 12, those who became hypertensive (hospital BP >140/90 mmHg) would be advised to continue the drug.
Results: Ninety-five patients were recruited. Six patients were excluded since they did not complete HBP measurement data.
After 2 weeks of antihypertensive drug discontinuation, 16 out of 89 patients enrolled were found to be HT by HBP. The rest 73 patients (82.0%) were remained NT. At week 12, 7 patients (7.9%) self-administrated drug prior to the visit date. Therefore, 66 patients (74.1%) were left for further analyses. Of them, 55 patients (61.8%) were still NT by hospital BP and 11 patients (12.3%) turned to be HT. There were no significant differences of all risk factors studied between those NT and HT, except male was found in a higher proportion than female (p = 0.021).
Conclusion: Fifty five patients (61.8%) out of 89 enrolled patients are still NT and able to stop anti-HT drug after 12 weeks
follow-up. Male had a higher rate to remain NT than female.

Keywords: Antihypertensive drug withdrawal