BMJ  2004;329:1404 (11 December), doi:10.1136/bmj.329.7479.1404

Letter

The PROGRESS trial three years later

Clear and accurate interpretations of studies are needed

EDITOR—Like Wennberg and Zimmermann, I am troubled by the interpretation of the results of PROGRESS published in the original Lancet article and reiterated by others; by the amalgamation of the perindopril and perindopril-indapamide arms under the rubric "perindopril based therapy"; and by the chief conclusions about such treatment attributed by the trialists.^{1 2}

Interestingly, this has affected my own work. A neurologist referee of a recent article on secondary stroke prevention I published with Kapral in the Canadian Journal of Neurological Sciences strongly criticised our paper for simply noting the difference in efficacy between the two active treatment arms of PROGRESS³; this anonymous reviewer adamantly stated that the trial was not sufficiently powered to show a distinction. Perhaps the best way to look at PROGRESS is that it is really two parallel but different randomised trials with the same control group. Therefore, combining these two very different treatment arms for analysis may be an oversimplification.

Moreover, the article by Wennberg and Zimmermann does not at all distract from implementation of the trial results, as argued by the PROGRESS trialists. With combination treatment with angiotensin converting enzyme inhibitors and diuretics we get the best of both worlds, and a combination indapamide-perindopril regimen exists and is manufactured by Servier. I also find it interesting that a higher dose of perindopril monotherapy (8 mg) did not prevent stroke in the recent massive EUROPA study, despite a reduction of 5/3 mm Hg in blood pressure.⁴

Institute for Clinical Evaluative Sciences, Division of Clinical Pharmacology, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Canada M4N 3M5 danhackam{at}cogeco.ca

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Competing interests: None declared.

References

1. Wennberg R, Zimmerman C. The PROGRESS trial three years later: time for a balanced report of effectiveness [with commentary by S MacMahon, B Neal, A Rodgers, J Chalmers]. BMJ 2004;329: 968-71. (23 October.)[Free Full Text]
2. PROGRESS Collaborative Group. Randomised trial of perinopril-based blood pressure lowering regimen among 6105 individuals with previous stroke or transient ischaemic attack. Lancet 2001;358: 1033-41.[CrossRef][ISI][Medline]
3. Hackam DG, Kapral MK. Progress in clinical neurosciences: pharmacotherapies for the secondary prevention of stroke. Can J Neurol Sci 2004;3: 295-303.
4. Fox KM for the European Trial on Reduction of Cardiac Events with Perindopril in Stable Coronary Artery Disease Investigators. Efficacy of perindopril in reduction of cardiovascular events among patients with stable coronary artery disease: randomised, double-blind, placebo-controlled, multicentre trial (the EUROPA study). Lancet 2003:362: 782-8.[CrossRef][ISI][Medline]

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