Urinary albumin excretion, blood pressure changes and hypertension incidence in the community: effect modification by kidney function

Both increased albuminuria and reduced kidney function may predict blood pressure (BP) progression in the community, while they exacerbate each other's effects. We investigated associations and interactions between these two risk factors, BP changes and hypertension incidence in community-dwelling elderly men. Observational study from the Uppsala Longitudinal Study of Adult Men, which included 1051 men (all aged 71 years) with assessments on urinary albumin excretion rate (UAER), 24-hour ambulatory BP monitoring (ABPM) and cystatin-C estimated glomerular filtration rate (eGFR). Of these, 574 men attended re-examination after 6 years, and ABPM measurements were again recorded to assess blood pressure changes and hypertension incidence. UAER was found to be associated with ABPM measurements both at baseline and longitudinally. In longitudinal analysis, there were significant interactions between UAER and kidney function in its association with the changes of systolic BP, mean arterial pressure and pulse pressure. After stratification for renal function state, UAER independently predicted BP changes only in those who had eGFR <60 mL/min/1.73 m2. At re-examination, 71 new cases of hypertension were recorded. In multivariable logistic models, similar interactions were observed on hypertension incidence: UAER was an independent predictor of incident hypertension only in those with reduced renal function. These associations were evident also in the subpopulation of non-diabetics and in participants with normal range UAER (<20 µg/min). In community-dwelling elderly men, UAER associates with BP progression and hypertension incidence, even within the normal range. Concurrent reduction of renal function modifies and exacerbates these associations.