doi: 10.1161/CIRCULATIONAHA.105.547240
(Circulation. 2005;112:e121.)
© 2005 American Heart Association, Inc.
Correspondence |
Letter Regarding Article by Wang et al, "Low-Grade Albuminuria and the Risks of Hypertension and Blood Pressure Progression"
Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy
It was with great interest that I read the article in Circulation by Wang et al,1 who reported on the results of a recent analysis of low-grade albuminuria (UA) performed within the Framingham Heart Study. The authors found that UA increased the future risk for development of hypertension among the normotensive segment of the Framingham cohort. They concluded that UA can be considered as a useful biomarker for better targeting prehypertensive individuals for nonpharmacological intervention. These results are at variance with those from the Hypertension and Ambulatory Recording VEnetia STudy (HARVEST) recently published by our group.2 In a cohort of 1033 young subjects screened for stage 1 hypertension and never treated for the disease, we found that UA was not helpful for identifying those subjects destined to develop sustained hypertension requiring antihypertensive therapy. The reason for the discrepancy between the Framingham and HARVEST findings could be the different mean age and blood pressure level of the 2 cohorts. It should be noted, however, that in the Framingham Heart Study important explanatory variables were not included in the regressions. Lifestyle factors such as physical activity habits or alcohol consumption, which may affect both UA and future blood pressure levels,3,4 were not taken into account by the Framingham investigators.1 Therefore, it would be interesting to know the impact of the inclusion of alcohol use and physical activity in their logistic regression. Furthermore, in the HARVEST study, an important variable that excluded UA from the final regression model was mean 24-hour blood pressure recorded with ambulatory monitoring techniques at baseline. As we and other investigators have found,5 24-hour blood pressure is a stronger correlate of UA than is clinic blood pressure and is a more accurate predictor of the development of hypertension. This casts some doubts on the cost effectiveness of UA in the routine assessment of prehypertensive subjects, at least when 24-hour ambulatory blood pressure monitoring data are available.
I believe that the predictive role of UA in the development of hypertension should be better defined before concluding that there is advantage to adding UA to the standard risk prediction model for all normotensive or prehypertensive subjects at this time.
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 Top References References |
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1. Wang TJ, Evans JC, Meigs JB, Rifai N, Fox CS, D’Agostino RB, Levy D, Vasan RS. Low-grade albuminuria and the risks of hypertension and blood pressure progression. Circulation. 2005; 111: 1370–1376.
2. Palatini P, Mormino P, Mos L, Mazzer A, Dorigatti F, Zanata G, Longo D, Garbelotto R, De Toni R, Graniero G, Pessina AC; HARVEST Study Group. Microalbuminuria, renal function and development of sustained hypertension: a longitudinal study in the early stage of hypertension. J Hypertens. 2005; 23: 175–182.[CrossRef][Medline] [Order article via Infotrieve]
3. Calle-Pascual AL, Martin-Alvarez PJ, Reyes C, Calle JR. Regular physical activity and reduced occurrence of microalbuminuria in type 2 diabetic patients. Diabetes Metab. 1993; 19: 304–309.
4. Klein R, Klein BE, Moss SE. Prevalence of microalbuminuria in older-onset diabetes. Diabetes Care. 1993; 16: 1325–1330.[Abstract]
5. Wiinberg N, Bang LE, Wachtell K, Larsen J, Olsen MH, Tuxen C, Hildebrandt PR, Rokkedal J, Ibsen H, Devereux RB. 24-h ambulatory blood pressure in patients with ECG-determined left ventricular hypertrophy: left ventricular geometry and urinary albumin excretion—a LIFE substudy. J Hum Hypertens. 2004; 18: 391–396.[CrossRef][Medline] [Order article via Infotrieve]
Framingham Heart Study, Framingham, Mass
We appreciate Dr Palatini’s interest in our study. As he points out, there were substantial differences between the participants in the Hypertension and Ambulatory Recording VEnetia STudy (HARVEST)1 and those in our investigation.2 HARVEST participants were younger, by
In our logistic models, additional adjustment for physical activity (assessed by a questionnaire) and alcohol use (number of drinks per week) did not significantly alter our findings: The odds ratio for incident hypertension associated with having a urinary albumin/creatinine ratio in the fourth quartile (as compared with the first quartile) was 1.76 (95% CI, 1.09 to 2.85; P=0.02).
We agree that 24-hour ambulatory blood pressure may provide information above and beyond clinical blood pressure for identifying the future risk of sustained hypertension. Ambulatory blood pressure was not measured in our study sample. Although urinary albumin excretion may be influenced by diurnal exposure to blood pressure, we submit that a spot urine test may be easier to obtain in routine clinical practice than a 24-hour ambulatory blood pressure recording.
As we stated in the article, we share Dr Palatini’s view that additional studies are needed to determine the incremental utility of urinary albumin measurements in the evaluation of individuals at risk of developing hypertension.
Response
2 decades, as compared with our participants. In addition, HARVEST participants were required to have a baseline systolic blood pressure of 140 to 159 mm Hg or a diastolic blood pressure of 90 to 99 mm Hg. Such individuals would have been classified as having prevalent hypertension in our study and excluded.2,3 We acknowledge that our findings (based on observations on a middle-aged nonhypertensive cohort) may not necessarily be generalizable to younger people with untreated hypertension.
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Disclosure
Dr Wang has received payment for contributing a chapter on hypertension to an electronic textbook sponsored by Novartis.
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TopReferencesReferences |
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1. Palatini P, Mormino P, Mos L, Mazzer A, Dorigatti F, Zanata G, Longo D, Garbelotto R, De Toni R, Graniero G, Pessina AC. Microalbuminuria, renal function and development of sustained hypertension: a longitudinal study in the early stage of hypertension. J Hypertens. 2005; 23: 175–182.[CrossRef][Medline] [Order article via Infotrieve]
2. Wang TJ, Evans JC, Meigs JB, Rifai N, Fox CS, D’Agostino RB, Levy D, Vasan RS. Low-grade albuminuria and the risks of hypertension and blood pressure progression. Circulation. 2005; 111: 1370–1376.
3. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, Jones DW, Materson BJ, Oparil S, Wright JT Jr, Roccella EJ; National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA. 2003; 289: 2560–2572.
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