Cardiovascular effects of tight versus usual blood-pressure control – Authors' reply

Abstract

Saurabh Rai and colleagues suggest that imbalances in drug treatment between the two groups may partly explain the different pattern of left-ventricular hypertrophy (LVH). However, this possibility is unlikely for several reasons. First, the number of antihypertensive drug classes patients were taking increased from baseline in both study groups (p<0·0001) without any statistical differences between the two groups (p=0·79). Second, when individual drug classes were examined separately, diuretics were given more frequently in the tight-control group than in the usual-control group (odds ratio 1·36, 95% CI 1·08–1·71; p=0·009). Diuretics are believed to be less effective than other drug classes for achieving regression of LVH.1Klingbeil AU Schneider M Martus P Messerli FH Schmieder RE A meta-analysis of the effects of treatment on left ventricular mass in essential hypertension.Am J Med. 2003; 115: 41-46Summary Full Text Full Text PDF PubMed Scopus (610) Google Scholar Contrary to Rai and colleagues' interpretation, we found no statistical evidence of a more frequent use of angiotensin-receptor blockers (ARBs) in the tight-control group (p=0·07). Rai and colleagues' argument that combination therapy induces regression of LVH “more quickly and completely than single agents” is poorly supported. They cite a small study in 24 patients,2Grandi AM Solbiati F Laurita E et al.Effects of dual blockade of renin-angiotensin system on concentric left ventricular hypertrophy in essential hypertension: a randomized, controlled pilot study.Am J Hypertens. 2008; 21: 231-237Crossref PubMed Scopus (30) Google Scholar a review article,3Devereux RB Therapeutic options in minimizing left ventricular hypertrophy.Am Heart J. 2000; 139: S9-S14Summary Full Text Full Text PDF PubMed Scopus (41) Google Scholar and a meta-analysis.4Schmieder RE Martus P Klingbeil A Reversal of left ventricular hypertrophy in essential hypertension: a meta-analysis of randomized double-blind studies.JAMA. 1996; 275: 1507-1513Crossref PubMed Google Scholar In the context of our study, it was impractical to compare various antihypertensive combinations because, on average, 2·8 and 2·9 drug classes were used at 1-year and 2-year follow-up, respectively. Hence, the potential drug combinations were so many to preclude any meaningful comparison. Furthermore, since the therapeutic management was tailored to every patient's need at each visit without any forced scheme, it was unfeasible to control for all episodes of uptitration or downtitration of treatment. Finally, since the readers of electrocardiographic tracings were unaware of the randomisation code, the potential bias introduced by the open design did not extend to the assessment of LVH, the primary endpoint of the study. Jonas Green and Adam Richards raise an apparent inconsistency with our previous publication with regard to the policy of downtitration of therapy in patients allocated to the usual control group and systolic blood pressure below 130 mm Hg. Once again, we remake the point that treatment could be either left unchanged or downtitrated, by protocol, at the total discretion and responsibility of the field investigator. This choice has been made not to contradict the guidelines, but to mimic as much as possible doctors' choices in everyday practice. We do not share the interpretation that such a policy led to a substantial underestimation of the potentially achievable blood pressure control in the usual-control group. A few numbers were misquoted in our printed article. The correct numbers of patients who achieved the target blood pressure in the two groups are shown in the table and were corrected in an erratum in the Sept 12 issue . Overall, the degree of blood pressure control was good. For comparison, a large survey in Italy reported a rate of systolic blood pressure control (<140 mm Hg) of 24% in treated hypertensive patients.5Volpe M Tocci G Trimarco B et al.Blood pressure control in Italy: results of recent surveys on hypertension.J Hypertens. 2007; 25: 1491-1498Crossref PubMed Scopus (121) Google ScholarTableAchieved systolic blood pressure at 2-year follow-up in the two study groupsUsual-control groupTight-control group<140 mm Hg66·9% (334/499)76·5% (388/507)<130 mm Hg27·3% (136/499)45·4% (230/507) Open table in a new tab We declare that we have no conflicts of interest. Cardiovascular effects of tight versus usual blood-pressure controlWe would like to draw the attention of readers to some important limitations of the study by Paolo Verdecchia and colleagues (Aug 15, p 525).1 Full-Text PDF Cardiovascular effects of tight versus usual blood-pressure controlThe Cardio-Sis trial1 asks whether a lower goal for systolic blood pressure (<130 mm Hg) is superior to the current goal (<140 mm Hg). Unfortunately, the trial does not answer this important question, because the control group protocol does not represent “usual care” under current guidelines. Full-Text PDF