Eur Respir J 2007; 29:217-218
Copyright ©ERS Journals Ltd 2007
From the authors
A. A. El Solh
Division of Pulmonary, Critical Care and Sleep Medicine, Dept of Medicine, University at Buffalo School of Medicine and Biomedical Sciences, Buffalo, NY, USA.
We thank S. Teramoto and colleagues for their comments on our recent article 1. We agree that changes in flow-mediated vasodilation (FMD) are influenced by a variety of intrinsic and extrinsic factors such as endogenous, environmental and familial factors 2, of which age, sex and body mass index (BMI) are the classic examples. Indeed, analysis by sex of our data showed that male participants had larger arterial diameters and smaller FMD at baseline compared with female subjects (6.1±2.6% in males and 8.0±1.7% in females). However, in contrast to the remarks of S. Teramoto and colleagues, the median FMD improvement after allopurinol treatment was larger in women (4.3%; 95% confidence interval (CI) 1.0–7.6%) than in their male counterparts (3.4%; 95% CI 1.5–5.4%); although not to a statistically significant degree. Correlation analyses also revealed no significant relationship between changes in FMD (before and after treatment) and either age (r = 0.2; p = 0.5) or BMI (r = 0.06; p = 0.85). We acknowledge that the power of the study is too small to detect any significant difference and we alluded to this limitation in the manuscript. As pointed out by S. Teramoto and colleagues, FMD is influenced by circulating levels of oestrogen and progesterone, and by the phase of the subject's menstrual cycle 3. This variability would have been significant had our female participants been of a child-bearing age; however, only one of the four female subjects fell into that category. Finally, we concur with S. Teramoto and colleagues that a larger sample size would be needed to confirm our findings. Now that our randomised clinical trial has shown potential efficacy, we hope it stimulates further long-term research studies to determine the role and side-effects of allopurinol in the treatment of obstructive sleep apnoea-related endothelial dysfunction.
REFERENCES
- El Solh AA, Saliba R, Bosinski T, Grant BJ, Berbary E, Miller N. Allopurinol improves endothelial function in sleep apnea: a randomised controlled study. Eur Respir J 2006;27:997–1002.[Abstract/Free Full Text]
- Moens AL, Goovaerts I, Claeys MJ, Vrints CJ. Flow-mediated vasodilation: a diagnostic instrument, or an experimental tool? Chest 2005;127:2254–2263.
- Sorensen KE, Dorup I, Hermann AP, Mosekilde L. Combined hormone replacement therapy does not protect women against the age-related decline in endothelium-dependent vasomotor function. Circulation 1998;97:1234–1238.
