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To the Editor:

We thank Dr Balta and colleagues[1] for their interest in our work, and would like to respond to their recent article.[2] We agree concerning the importance of investigating the pathological status in patients with masked hypertension (MHT), including inflammation markers. We reanalyzed the association between endothelial dysfunction (ie, the flow-mediated vasodilation [FMD] magnitude [ΔFMD] and the integrated FMD response [FMD-AUC120]) and other pathological status.

We also measured the urinary albumin-creatinine ratio (UACR) in our studies[3],[4] (Table1). The UACR in the patients with sustained hypertensive (office blood pressure [BP] ≥140/90 mm Hg and home BP ≥135/85 mm Hg) was significantly higher than that among both the patients with white-coat hypertension (office BP ≥140/90 mm Hg and home BP <135/85 mm Hg) and the patients with normotension (office BP <140/90 mm Hg and home BP < 135/85 mm Hg). The differences in UACR in the MHT group and those in the normotensive patients were not statistically significant, but the underlying reason might be a type II error. This finding was similar to that obtained in our previous study.[5]

Table 1. Urinary Albumin-Creatinine Ratio in BP Subgroups
 Normotension (n=90)White-Coat Hypertension (n=41)Masked Hypertension (n=41)Sustained Hypertension (n=85)P Values
  1. Abbreviations: BP, blood pressure; UACR, urinary albumin-creatinine ratio. Data are shown as median value (25% value–75% value). The overall P value was calculated using analysis of variance. aP<.001 vs normotension. bP<.05 vs white-coat hypertension.

UACR9.2 (6.3–24.4)12.7 (6.1–27.6)14.1 (7.6–45.7)14.6 (7.5–81.6)a,b<.001

FMD-AUC120 was significantly inversely associated with log UACR (r=−0.18, P=.008), but ΔFMD was not associated with log UACR (r=−0.06, P=.35). FMD-AUC120 reflected kidney disease, but ΔFMD did not.

The UACR was significantly higher in the patients in the lowest tertile for FMD-AUC120 (FMD-AUC120 <5.0 mmxs, n=86) than in the patients in the highest tertile for FMD-AUC120 (FMD-AUC120 ≥11.0 mmxs, n=86 [P<.001]; Figure1, panel A), but the UACR was similar in the patients in the lowest and highest tertiles for ΔFMD (P=1.0; Figure1, panel B).

image

Figure 1. Urinary albumin-creatinine ratio in patients with tertiles of integrated flow-mediated vasodilation (FMD-AUC120) and magnitude of flow-mediated vasodilation (∆FMD). Intergroup differences were tested by the Bonferroni test.

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We did not evaluate sedentary habits or liver function. We measured the high-sensitivity CRP (hsCRP) level, but log-hsCRP was not associated with ΔFMD or with FMD-AUC120.

As Dr Balba commented,[1] endothelial dysfunction, which was measured as FMD (not ΔFMD, but FMD-AUC120), might be associated with kidney disease. However, in our patient population, there was no association between FMD and inflammation. We previously demonstrated that FMD-AUC120 was associated with the Framingham risk score,[3] and further studies including more patients are needed to clarify the associations among FMD-AUC120, inflammation, and other pathological status factors.

References

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  • 1
    Balta S, Kucuk U, Arslan Z, Demirkol S, Unlu M. Masked hypertension as an unrecognized destructive condition. J Clin Hypertens (Greenwich). 2013; doi: 10.1111/jch.12240.
  • 2
    Balta S, Demirkol S, Celik T, Unlu M, Kucuk U, Arslan Z. Inflammatory markers should be assessed together with cardiovascular risk factors by clinicians in masked hypertension. J Clin Hypertens (Greenwich). 2013;15:443444.
  • 3
    Kabutoya T, Hoshide S, Ogata Y, Iwata T, Eguchi K, Kario K. The time course of flow-mediated vasodilation and endothelial dysfunction in patients with a cardiovascular risk factor. J Am Soc Hypertens. 2012;6:109116.
  • 4
    Kabutoya T, Hoshide S, Ogata Y, Eguchi K, Kario K. Masked hypertension defined by home blood pressure monitoring is associated with impaired flow-mediated vasodilatation in patients with cardiovascular risk factors. J Clin Hypertens (Greenwich). 2013;15:630636.
  • 5
    Ishikawa J, Hoshide S, Eguchi K, et al. Masked hypertension defined by ambulatory blood pressure monitoring is associated with an increased serum glucose level and urinary albumin-creatinine ratio. J Clin Hypertens (Greenwich). 2010;12:578587.