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Drs Goldsmith and Covic 1 rightly conclude that it is premature to attribute cardiovascular benefits of antihypertensive drug use in hemodialysis patients to blood pressure lowering alone. Our meta-analysis points out the sharp difference between cohort studies and randomized trials; the former show harm with spontaneous fall in BP whereas the latter show a benefit with antihypertensive drug use 2. Heerspink et al in their meta-analysis concluded, “treatment with agents that lower blood pressure should routinely be considered for individuals undergoing dialysis to reduce the very high cardiovascular morbidity and mortality rate in this population. 3” However, given the problems with the current randomized trials, and the heterogeneity in results, we concluded: “adequately powered randomized trials are required to confirm these observations, especially among those with hypertension”. Our meta-analysis should not be taken as “proof” that blood pressure should be lowered in hemodialysis patients. Indeed our conclusions are consistent with Drs Goldsmith and Covic call for the urgent need for well-designed randomized trials in this vulnerable population.
We had three fewer studies in our meta-analysis compared to the one by Heerspink et al 3. Two of the 3 studies in the meta-analysis of Heerspink et al were published in abstract form. The third study was done in peritoneal dialysis patients to test the notion whether ACE inhibitors protect the decline in residual renal function; this study was substantially different from other studies in hemodialysis patients which were designed to study cardiovascular protection 4. Accordingly, we feel that the results of our meta-analysis accurately reflect the state of the art at least in hemodialysis patients. We, like Heerspink et al, found heterogeneity between studies but unlike these authors we found that the effect on cardiovascular risk was modified by consideration of hypertension status. Therefore, studying hypertensive patients should have a more urgent priority compared to lowering blood pressure among normotensive patients on hemodialysis. If such a trial is undertaken we recommend blood pressure monitoring should be performed outside the dialysis unit than simply measuring blood pressures before and after dialysis 5,6.