CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Apoor S. Gami, MD* and
Victor M. Montori, MD, MSc
* Mayo Clinic College of Medicine, Cardiovascular Diseases and Internal Medicine, 200 First Street SW, Rochester, Minnesota, 55905 (Email: gami.apoor{at}mayo.edu).
We appreciate the comments of Dr. Inchiostro and colleagues regarding one of the more controversial topics regarding the metabolic syndrome (MetSyn), namely whether it poses cardiovascular risk beyond what is already conferred by the cardiac risk factors that comprise it. We attempted to address this question by including in a single meta-analysis the results from individual studies that had included MetSyn and its component risk factors into the same multivariate model (1).
Sattar et al. (2) did report an effect estimate (hazard ratio [HR] 1.4; 95% confidence interval [CI] 1.05 to 1.89) from a multivariate model that included the MetSyn, body mass index, blood pressure, lipid abnormalities, glucose abnormalities, and C-reactive protein (which represent the clustering of risk factors that comprise the MetSyn), and we included this in the analysis (2).
Dr. Inchiostro and colleagues are correct that the report by Schillaci et al. (3) did not include "mention of any analysis adjusting the risk associated with the [MetSyn] for its specific components," but they offered an estimate that was adjusted for MetSyn, age, gender, smoking, high blood pressure, cholesterol levels, renal function, and ventricular hypertrophy (3). Thus, this analysis included some of the components of the MetSyn, and we included it in the analysis.
In their report, McNeill et al. (4) stated that the effect estimate was near the null value for "separate, multivariate-adjusted models that also included an indicator for the presence of the metabolic syndrome" (4). Our interpretation of this was that multiple separate models were created that included MetSyn and single-risk factors. We did not consider Dr. Inchiostro and colleagues’ alternate interpretation that 1 model was created that included MetSyn and all its component risk factors. An analysis based on the latter interpretation provides a summary result for the three studies (HR 1.2; 95% CI 1.02 to 1.41) that does not change our overall interpretation.
We appreciate Dr. Inchiostro and colleagues’ comments, and we generally agree that the available data are imperfect. Our decision to include the effect estimates from the 3 studies reflected our best effort to appropriately answer an important question with all the data that are available.
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References
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- Gami AS, Witt BJ, Howard DE, et al. Metabolic syndrome and risk of incident cardiovascular events and death: a systematic review and meta-analysis of longitudinal studies J Am Coll Cardiol 2007;49:403-414.[Abstract/Free Full Text]
- Sattar N, Gaw A, Scherbakova O, et al. Metabolic syndrome with and without C-reactive protein as a predictor of coronary heart disease and diabetes in the West of Scotland Coronary Prevention Study Circulation 2003;108:414-419.[Abstract/Free Full Text]
- Schillaci G, Pirro M, Vaudo G, et al. Prognostic value of the metabolic syndrome in essential hypertension J Am Coll Cardiol 2004;43:1817-1822.[Abstract/Free Full Text]
- McNeill AM, Rosamond WD, Girman CJ, et al. The metabolic syndrome and 11-year risk of incident cardiovascular disease in the Atherosclerosis Risk in Communities Study Diabetes Care 2005;28:385-390.[Abstract/Free Full Text]
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