European Heart Journal Advance Access originally published online on June 2, 2006
European Heart Journal 2006 27(13):1632; doi:10.1093/eurheartj/ehl050
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An open label, single-centre, randomized trial of spinal cord stimulation vs. percutaneous myocardial laser revascularization in patients with refractory angina pectoris: the SPiRiT trial: reply
Papworth Hospital
Cardiology
Papworth Everard
Cambridge
CB3 8RE
UK
Papworth Hospital
Cardiology
Papworth Everard
Cambridge
CB3 8RE
UK
E-mail address: sadia.khan{at}papworth.nhs.uk
We thank Dr de Vries and colleagues for their comments. In response, we would like to make the following points.
First, with regards to the study by Tio et al.,1 in our introduction, we did not intend to present a comprehensive review of all treatments for refractory angina, only to highlight the paucity of randomized trial data. Dr de Vries et al. correctly state that there are other randomized studies of spinal cord stimulation (SCS), apart from the ESBY study that we cited in our introduction, that fulfil accepted criteria to be deemed ‘trials.’ However, these other studies suffer from methodological issues that we felt were sufficiently important that their results should best be considered as hypothesis generating rather than supporting. Typically, these studies had small sample sizes (10–12 per group) and no sample size calculation, yet reported multiple outcomes (the study cited, for example, enrolled 12 patients in the SCS group and 13 controls). We should have been more explicit in our reasoning for proposing that the ESBY study was the only randomized trial to support SCS.
Secondly, this study was not powered for within group analyses and there are justifiable concerns that such findings may represent regression to the mean. These data were contained in original submissions but removed as a result of criticism from multiple reviewers.
Thirdly, baseline data were summarized as mean (SD) to enable the population from which these subjects were drawn to be characterized. As some patients did not experience angina during the exercise test, time to angina was estimated from Kaplan–Meier survival curves, and summarised as mean (SEM). All follow-up data were reported as mean (SEM) as we are interested in the precision of the mean estimates.
Next, with regards to the ischaemic burden during exercise tolerance test, this was not an a priori endpoint. As a generalization, one of our concerns regarding the literature in this field is the tendency of studies to report positive secondary outcomes when the primary outcome is negative. This is particularly the case when studies have not been adequately powered for such secondary endpoints. Nevertheless, following the comments of Dr de Vries and colleagues we have analysed these data and can report there is no significant difference between the two groups.
Finally, the SPiRiT acronym was the source of some mirth during the study as participants and workers alike struggled to find the meaning in its form. The origin may be found (with some imagination to be fair) in the Spinal cord stimulation vs. Percutaneous myocardial laser revascularization Randomised Trial.
References
- Tio RA, Tan ES, Jessurun GA, Veeger N, Jager PL, Slart RH, de Jong RM, Pruim J, Hospers GA, Willemsen AT, De Jongste MJ, van Boven AJ, van Veldhuisen DJ, Zijlstra F. (2004) PET for evaluation of differential myocardial perfusion dynamics after VEGF gene therapy and laser therapy in end-stage coronary artery disease. J Nucl Med 45:1437–1443.
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