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Overview of the i-SEARCH Global Study

Cardiovascular Risk Factors and Microalbuminuria in Hypertensive Individuals


Microalbuminuria (MAU) is a highly predictive, sensitive, inexpensive and easily repeatable marker of cardiovascular risk and all-cause mortality in hypertensive patients. The international, observational, practice-based study i-SEARCH (Survey for Evaluating Microalbuminuria Routinely by Cardiologists in patients with Hypertension) was designed to assess the frequency with which MAU occurred in a large outpatient population who were currently treated or newly diagnosed with hypertension and were under professional care. The primary aim of the study was to define the prevalence of MAU in hypertensive outpatients attending a cardiologist or internist (i-SEARCH A) and to compare hypertensive outpatients with or without coronary artery disease (i-SEARCH B). A secondary objective was to establish a correlation between MAU and known cardiovascular risk factors. A total of 21 050 patients from 26 countries were included in the primary analysis. Overall, this study demonstrated a very high worldwide prevalence (58.4%) of MAU in high-risk cardiovascular patients, but with a considerable variation across countries. MAU was more prevalent in patients with coronary artery disease than in those without. It was also significantly related to the presence of specific predictors, including male gender, abnormally high waist circumference, increased blood pressure levels (systolic ≥120 mmHg, diastolic ≥100 mmHg), creatinine clearance ≥50 mL/min, or clinical conditions such as diabetes mellitus, congestive heart failure, history of cerebral pathology, and peripheral arterial disease. Since the presence of MAU reflects long-term detrimental effects on the cardiovascular system, these results indicate the high, and in many cases hidden, burden of cardiovascular diseases among the hypertensive patients seen by cardiologists. This article discusses the main results of the study and the potential implications of ongoing analyses included in the core clinical study programme.

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  1. 1.

    Karalliedde J, Viberti G. Microalbuminuria and cardiovascular risk. Am J Hypertens 2004 Oct; 17(10): 986–93

  2. 2.

    Viberti G. Prognostic significance of microalbuminuria. Am J Hypertens 1994 Sep; 7(9 Pt 2): 69S–72S

  3. 3.

    Volpe M. Microalbuminuria screening in patients with hypertension: recommendations for clinical practice. Int J Clin Pract 2008 Jan; 62(1): 97–108

  4. 4.

    Klausen KP, Parving HH, Scharling H, et al. Microalbuminuria and obesity: impact on cardiovascular disease and mortality. Clin Endocrinol (Oxf). Epub 2008 Sep 17

  5. 5.

    Klausen KP, Parving HH, Scharling H, et al. The association between metabolic syndrome, microalbuminuria and impaired renal function in the general population: impact on cardiovascular disease and mortality. J Intern Med 2007 Oct; 262(4): 470–8

  6. 6.

    Jensen JS, Feldt-Rasmussen B, Strandgaard S, et al. Arterial hypertension, microalbuminuria, and risk of ischemic heart disease. Hypertension 2000 Apr; 35(4): 898–903

  7. 7.

    Jensen JS, Feldt-Rasmussen B, Borch-Johnsen K, et al. Microalbuminuria and its relation to cardiovascular disease and risk factors: a population-based study of 1254 hypertensive individuals. J Hum Hypertens 1997 Nov; 11(11): 727–32

  8. 8.

    Reboldi G, Gentile G, Angeli F, et al. Microalbuminuria and hypertension. Minerva Med 2005 Aug; 96(4): 261–75

  9. 9.

    Karalliedde J, Viberti G. Hypertension and microalbuminuria: risk factors for cardiovascular disease in diabetes. Curr Hypertens Rep 2005 Feb; 7(1): 1–2vv

  10. 10.

    Parving HH, Chaturvedi N, Viberti G, et al. Does microalbuminuria predict diabetic nephropathy? Diabetes Care 2002 Feb; 25(2): 406–7

  11. 11.

    Viberti GC, Friedman R. Predictive value of microalbuminuria in longstanding insulin dependent diabetes [letter]. BMJ 1993 Jan 23; 306(6872): 271; author reply 2

  12. 12.

    Volpe M, Cosentino F, Ruilope LM. Is it time to measure microalbuminuria in hypertension? J Hypertens 2003 Jul; 21(7): 1213–20

  13. 13.

    Viberti G, Thomas S. Should we screen for microalbuminuria in essential hypertension? Am J Kidney Dis 1999 Dec; 34(6): 1139–41

  14. 14.

    Mancia G, De Backer G, Dominiczak A, et al. 2007 guidelines for the management of arterial hypertension: the Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). J Hypertens 2007 Jun; 25(6): 1105–87

  15. 15.

    Volpe M, Tocci G, Trimarco B, et al. Blood pressure control in Italy: results of recent surveys on hypertension. J Hypertens 2007 Jul; 25(7): 1491–8

  16. 16.

    Rossi MC, Nicolucci A, Pellegrini F, et al. Identifying patients with type 2 diabetes at high risk of microalbuminuria: results of the DEMAND (Developing Education on Microalbuminuria for Awareness of reNal and cardiovascular risk in Diabetes) study. Nephrol Dial Transplant 2008 Apr; 23(4): 1278–84

  17. 17.

    Hovind P, Tarnow L, Rossing P, et al. Predictors for the development of microalbuminuria and macroalbuminuria in patients with type 1 diabetes: inception cohort study [letter]. BMJ 2004 May 8; 328(7448): 1105

  18. 18.

    Pruijm MT, Madeleine G, Riesen WF, et al. Prevalence of microalbuminuria in the general population of Seychelles and strong association with diabetes and hypertension independent of renal markers. J Hypertens 2008 May; 26(5): 871–7

  19. 19.

    Agyemang C, van Valkengoed I, van den Born BJ, et al. Prevalence of microalbuminuria and its association with pulse pressure in a multi-ethnic population in Amsterdam, the Netherlands. The SUNSET Study. Kidney Blood Press Res 2008; 31(1): 38–46

  20. 20.

    Polonia J, Carmona J, Mendes E, et al. Prevalence of microalbuminuria in non-diabetic hypertensive patients attended by Portuguese GPs. Rev Port Cardiol 2007 Jun; 26(6): 637–44

  21. 21.

    Yeung VT, Lee KF, Chan SH, et al. MicroAlbuminuria Prevalence Study (MAPS) in hypertensive type 2 diabetic patients in Hong Kong. Hong Kong Med J 2006 Jun; 12(3): 185–90

  22. 22.

    Buranakitjaroen P, Deerochanawong C, Bunnag P. Microalbuminuria prevalence study (MAPS) in hypertensive patients with type 2 diabetes in Thailand. J Med Assoc Thai 2005 Nov; 88(11): 1624–9

  23. 23.

    Pontremoli R, Sofia A, Ravera M, et al. Prevalence and clinical correlates of microalbuminuria in essential hypertension: the MAGIC study. Microalbuminuria: A Genoa Investigation on Complications. Hypertension 1997 Nov; 30(5): 1135–43

  24. 24.

    Dixon AN, Raymond NT, Mughal S, et al. Prevalence of microalbuminuria and hypertension in South Asians and white Europeans with type 2 diabetes: a report from the United Kingdom Asian Diabetes Study (UKADS). Diab Vasc Dis Res 2006 May; 3(1): 22–5

  25. 25.

    Barnett AH. Preventing renal complications in diabetic patients: the Diabetics Exposed to Telmisartan And enalaprIL (DETAIL) study. Acta Diabetol 2005 Apr; 42Suppl. 1: S42–9

  26. 26.

    Dalla Vestra M, Pozza G, Mosca A, et al. Effect of lercanidipine compared with ramipril on albumin excretion rate in hypertensive type 2 diabetic patients with microalbuminuria: DIAL study (diabete, ipertensione, albuminuria, lercanidipina). Diabetes Nutr Metab 2004 Oct; 17(5): 259–66

  27. 27.

    Viberti G, Wheeldon NM. Microalbuminuria reduction with valsartan in patients with type 2 diabetes mellitus: a blood pressure-independent effect. Circulation 2002 Aug 6; 106(6): 672–8

  28. 28.

    Parving HH, Lehnert H, Brochner-Mortensen J, et al. The effect of irbesartan on the development of diabetic nephropathy in patients with type 2 diabetes. N Engl J Med 2001 Sep 20; 345(12): 870–8

  29. 29.

    Viberti G, Chaturvedi N. Angiotensin converting enzyme inhibitors in diabetic patients with microalbuminuria or normoalbuminuria. Kidney Int Suppl 1997 Dec; 63: S32–5v

  30. 30.

    Viberti G, Mogensen CE, Groop LC, et al. Effect of captopril on progression to clinical proteinuria in patients with insulin-dependent diabetes mellitus and microalbuminuria. European Microalbuminuria Captopril Study Group. JAMA 1994 Jan 26; 271(4): 275–9

  31. 31.

    Ibsen H, Olsen MH, Wachtell K, et al. Reduction in albuminuria translates to reduction in cardiovascular events in hypertensive patients: losartan intervention for endpoint reduction in hypertension study. Hypertension 2005 Feb; 45(2): 198–202

  32. 32.

    Casas JP, Chua W, Loukogeorgakis S, et al. Effect of inhibitors of the renin-angiotensin system and other antihypertensive drugs on renal outcomes: systematic review and meta-analysis. Lancet 2005 Dec 10; 366(9502): 2026–33

  33. 33.

    Ibsen H, Wachtell K, Olsen MH, et al. Does albuminuria predict cardiovascular outcome on treatment with losartan versus atenolol in hypertension with left ventricular hypertrophy? A LIFE substudy. J Hypertens 2004 Sep; 22(9): 1805–11

  34. 34.

    Böhm M, Thoenes M, Danchin N, et al. Association of cardiovascular risk factors with microalbuminuria in hypertensive individuals: the i-SEARCH global study. J Hypertens 2007 Nov; 25(11): 2317–24

  35. 35.

    Grassi G, Quarti-Trevano F, Dell’oro R, et al. Essential hypertension and the sympathetic nervous system. Neurol Sci 2008 May; 29Suppl. 1: S33–6

  36. 36.

    Grassi G, Seravalle G, Quarti-Trevano F, et al. Excessive sympathetic activation in heart failure with obesity and metabolic syndrome: characteristics and mechanisms. Hypertension 2007 Mar; 49(3): 535–41

  37. 37.

    Cosentino F, Volpe M. Hypertension, stroke, and endothelium. Curr Hypertens Rep 2005 Feb; 7(1): 68–71

  38. 38.

    Cosentino F, Eto M, De Paolis P, et al. High glucose causes upregulation of cyclooxygenase-2 and alters prostanoid profile in human endothelial cells: role of protein kinase C and reactive oxygen species. Circulation 2003 Feb 25; 107(7): 1017–23

  39. 39.

    Volpe M, Cosentino F. Abnormalities of endothelial function in the pathogenesis of stroke: the importance of endothelin. J Cardiovasc Pharmacol 2000; 35(4 Suppl. 2): S45–8

  40. 40.

    Böhm M, Reil JC, Danchin N, et al. Association of heart rate with microalbuminuria in cardiovascular risk patients: data from i-SEARCH. J Hypertens 2008 Jan; 26(1): 18–25

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The authors wish to thank Giuliano Tocci, MD, for helping with preparing and revising the present manuscript. i-SEARCH was sponsored by an unrestricted grant by Sanofi-Aventis, France. M.B., N.D. and M.V. received honoraria from Sanofi-Aventis. J.C.R. and M.B. are supported by the Deutsche Forschungsgemeinschaft (DFG, KFO 196).

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Correspondence to Prof. Michael Böhm.

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Böhm, M., Thoenes, M., Danchin, N. et al. Overview of the i-SEARCH Global Study. High Blood Press Cardiovasc Prev 15, 217–224 (2008).

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Key words

  • microalbuminuria
  • hypertension
  • coronary artery disease
  • cardiovascular risk
  • cardiovascular mortality