Managing hypertension in patients with renal disease and diabetes

The correspondents have raised issues that were discussed during the course of our deliberations as we developed the recommendations.

Alan Bell questions the recommendations for treatment of patients with hypertension and renal disease especially regarding the role of nondihydropyridine calcium-channel blockers. Both in the treatment recommendations for hypertensive patients with renal disease as well as in the other recommendations, the primary basis for designating specific drugs as first-line therapy was effective reduction not only of blood pressure but also of the ultimate end points, namely rates of hypertension-related cardiovascular complications. Thus, the designation of ACE inhibitors as first-line therapy for hypertensive patients with renal disease was based on evidence that these drugs are effective in reducing the development of renal failure and renal complications (beyond surrogate end points such as serum creatinine levels and proteinuria).1 As Bell points out, advantages of nondihydropyridine calcium-channel blockers over dihydropyridine calcium-channel blockers may have been demonstrated in the context of measures of renal hemodynamics or proteinuria. However, the lack of head-to-head comparisons between ACE inhibitors and a nondihydropyridine calcium-channel blocker in "hard outcome" studies was the primary basis for not including them for this indication. With the conclusion of the recent spate of megatrials (including those assessing the effects of nondihydropyridine calcium-channel blockers on hard end points) a more definitive recommendation regarding this class of drugs in patients with renal insufficiency might be anticipated. Apropos, we have organized a process to continuously review the hypertension literature and update all of our hypertension recommendations. Recognizing the poor uptake of recommendations in clinical practice, we have also linked this recommendations development process to a formal implementation plan coordinated by Health Canada and including a range of stakeholders involved in hypertension management.

Roland Grad and Stephen Hanley raise a thoughtful question regarding the basis of the recommendation for a target blood pressure of less than 130/80 mm Hg for patients with hypertension and diabetes. As they identify, the main impetus for the target for diastolic blood pressure of < 80 mm Hg was the diabetic subgroup of the HOT study.2 The grade C ascription was based on the diastolic blood pressure recommendation. The systolic target of 130 mm Hg was based on extrapolation from several sources. For the large subgroup of diabetic patients with some degree of nephropathy the target was based on studies of the greater population of patients with renal insufficiency for whom a mean arterial pressure target of 98 mm Hg (130/80 mm Hg) has been shown to be associated with a reduced decline in glomerular filtration rate and renal complications.1 Studies such as HOPE3 have reinforced the concept that for those patients at highest risk for atherosclerotic complications, blood pressure reduction even within the range nominally considered as normal (although epidemiologically associated with incremental risk for blood pressure related complications) would result in appreciable reductions in event rates. Parenthetically, this target for systolic blood pressure is consistent with that recommended by the World Health Organization - International Society of Hyptertension4 as well as the US Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure.5

Competing interests: See original article.1