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(Circulation. 2000;101:e162.)
© 2000 American Heart Association, Inc.

Circulation Electronic Pages

Can the Results be Explained by Poor Randomization and Nonpertinent Comparisons?

Sture Blomberg, MD, PhD

Department of Anesthesia and Intensive Care Medicine Sahlgren’s University Hospital, Gothenburg, Sweden, E-mail sblombrg@algonet.se

	Introduction

 
To the Editor:

I am writing regarding the article, "Anti-Ischemic and Anti-Anginal Effects of Thoracic Epidural Anesthesia Versus Those of Conventional Medical Therapy in the Treatment of Severe Refractory Unstable Angina Pectoris" by Olausson et al.¹

While doing comparative graphs for a lecture, I found several inconsistencies in the article that diminish its scientific value. The main inconsistency is found in Table 1. During a run-in period, the patients were treated with both nitroglycerin and heparin infusions for 82±18 versus 122±20 and 53±7 versus 104±13 hours, respectively, for controls and the group with thoracic epidural anesthesia (TEA). These differences were reported as nonsignificant by the authors. However, when recalculating the statistics, I found values of P<0.14 and P<0.0015 for the nitroglycerin and heparin infusions, respectively. Thus, at least in terms of the heparin infusion, it seems that the patients might not have been properly randomized.

In addition, Tables 2 and 3 contain several inconsistencies. For example, in Table 2, the "duration of ischemia per patient with ischemia" was given as 3.1 versus 0.8 minutes for controls versus TEA patients, which seems very low when comparing these values with other numbers in the table. My calculations result in the values 32.2 versus 17.25 minutes (355 minutes/11 patients and 69 minutes/4 patients, respectively). Is this correct, or does the duration of ischemia per patient with ischemia denote something else? Also, on the following line of Table 2, the number 32.2 appears as a measure of ischemic burden (area under the . . . [Full Text of this Article]

Sven-Erik Ricksten, MD, PhD; Karin Olausson, MD; Helga Magnusdottir, MD; Leon Lurje, MD; Bertil Wennerblom, MD, PhD; Håkan Emanuelsson, MD, PhD

Departments of Anesthesia and Intensive Care and Cardiology, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden, E-mail sven-erik.ricksten@aniv.gu.se