Microalbuminuria and all-cause mortality in treated hypertensive individuals: does sex matter? The Nord-Trøndelag Health Study (HUNT), Norway.

BACKGROUND: In hypertensive individuals, few prospective studies are available in which the association between microalbuminuria (MA) and all-cause mortality in the 2 sexes have been studied within the same population. METHODS AND
RESULTS: We conducted a 4.3-year follow-up of 2307 men and 3062 women (> or =20 years old) with self-reported treated hypertension, all identified in the Nord-Trøndelag Health Study (HUNT), Norway, 1995 to 1997 (n=65 258). The main outcome measures were relative risk (RR) of all-cause mortality according to increasing albuminuria, defined at different levels of albumin-to-creatinine ratio (ACR). There was a consistent positive association between increasing ACR and all-cause mortality in men. The adjusted RR for ACR in the fourth quartile (> or =1.70 mg/mmol) was 1.6 (95% CI, 1.0 to 2.6), compared with ACR in the first quartile (<0.55 mg/mmol). The corresponding RR in women was 1.5 (95% CI, 0.8 to 3.1). We found a positive association between mortality and increasing number of urine samples with ACR above different cutoff levels, especially in men. In 3 urine samples, the lowest ACR level associated with mortality in men was 0.86 mg/mmol, RR 1.6 (95% CI, 1.1 to 2.4). The sex differences persisted after exclusion of those who died during the first year of follow-up, those with hypertension not treated optimally, and those with known cardiovascular disease.
CONCLUSIONS: The association between ACR and all-cause mortality was stronger in treated hypertensive men than in women. The persistent sex differences indicate that hypertensive women tolerate MA better than men and that MA in women should be interpreted differently than in men.