From the Authors:
We appreciate Dr. Mirrakhimov’s and Dr. Lin’s comments regarding our article in the Journal (1) studying the association between obstructive sleep apnea (OSA) and serum high-sensitivity troponin (hs-TnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP) in 1,645 community-dwelling subjects free of coronary heart disease and heart failure from the intersection between the Atherosclerosis Risk in the Communities (ARIC) and the Sleep Heart Health Study (SHHS). We agree with Dr. Mirrakhimov that our study’s finding may not be generalizable to persons of nonwhite race/ethnicity. As with most previous studies evaluating the relationship between OSA and biomarkers of myocardial injury, the population participating in both ARIC and SHHS was predominantly white. To the best of our knowledge, despite findings of significant race-related differences in the sleep architecture and OSA symptoms (2), there is a lack of robust data on the cardiovascular implications of OSA in several ethnic populations, in particular Hispanics (3). Further studies will be necessary to elucidate whether the association between hs-TnT and OSA severity is also applicable to other ethnic populations and to clarify the cardiovascular implications of OSA more generally in these understudied populations. In this respect, several ongoing NHLBI cohort studies, including the Jackson Heart Study in African Americans (4) and the Study of Latinos (5), offer a unique potential opportunity.
Dr. Lin’s letter raises the possibility that the negative association between NT-proBNP and OSA severity noted in our unadjusted analysis may be confounded by the differential distribution of sex by OSA severity. We agree with Dr. Lin that there are important sex-based differences in both the pathophysiology of OSA (6) and the cardiac response to insult and altered loading conditions (7). In our study, the association between OSA and NT-proBNP remained negative and strongly significant (P = 0.007), even after adjusting for sex and age. After further adjusting for body mass index, this association was no longer significant (P = 0.05). Similarly, in our dataset, sex did not modify the association between respiratory disturbance index and NT-proBNP level (P for interaction = 0.21). An exploratory sex-stratified analysis found a negative association in women of marginal significance (P = 0.05) and a null association in men. Our findings indicate a need for further research to address potential sex differences in cardiovascular biomarker responses to OSA-related stresses.
Footnotes
Author disclosures are available with the text of this letter at www.atsjournals.org.
References
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