Letters Section Editor: Robert M. Golub, MD, Senior Editor.
To the Editor: In their study of the relationship between diurnal blood pressure and congestive heart failure (CHF), Dr Ingelsson and colleagues1 used 5 models to adjust for several covariates, including use of antihypertensive medications, prior myocardial infarction, diabetes, smoking, body mass index, and serum cholesterol level. However, we are concerned that the results of the study may have been confounded by chronic kidney disease (CKD). No measures of kidney function were provided to estimate glomerular filtration rate (GFR) of the study participants. While the incidence of CKD is not known for the Swedish population or in this middle-aged cohort, of whom 50% had hypertension, 10% had diabetes, and in whom overall body mass index was elevated, it is likely that at least 10% possessed moderate CKD (GFR<60 mL/min per 1.73 m2).2 It is also likely that approximately 50% had mild CKD (GFR 60-89 mL/min per 1.73 m2).2
Coca SG, Parikh CR. Congestive Heart Failure and Diurnal Blood Pressure Pattern. JAMA. 2006;296(23):2799-2800. doi:10.1001/jama.296.23.2799