To the Editor.
—In reference to the letter by Grenfell,1 published in the October 1983 Archives, the rapid return of hypertension in patients studied by him is most likely a consequence of the patient population he studied. Whereas the investigations by Grenfell included patients with moderate and severe hypertension, our study consisted only of patients with mild hypertension who had well-controlled BPs while receiving diuretic therapy. We stated in our 1982 Archives article that experience indicated that "patients with moderate and severe hypertension showed rapid return of BP to hypertensive levels."2(p2265) We also stated that "physicians and patients must understand the need for continued surveillance so that medication can be reinstituted if BP rises."2(p2268) In view of these precautions, we do not believe a trial "off" therapy, restricted only to patients with mild hypertension maintained under continued follow-up, is as dangerous as Grenfell stated.Other investigators have