Chapter 1: Introduction

Low grade albuminuria as a risk factor for subtypes of stroke - the HUNT Study in Norway

BACKGROUND AND PURPOSE

Albuminuria is a marker for endothelial dysfunction and knowledge on its association with stroke and stroke subtypes are limited.

METHODS

Corresponding data from 7261 participants of the population-based HUNT2 study (1995-1997) was linked with hospital records, identified all patients registered and diagnosed with a first-time stroke. Each diagnosis was validated by reviewal of the medical record appertaining to the individual. We then applied Cox proportional hazard models to estimate the hazard ratios (HRs) for the association between albuminuria (measured as albumin-to-creatinine-ratio, ACR) and diagnosis of stroke and stroke subtypes.

RESULTS

703 (9.7%) participants developed a first ischemic stroke during a median follow-up of 15 years. Higher albuminuria was associated with a higher rate for ischemic stroke and the risk rose steadily with increasing ACR (15% increment per unit increase in ACR concentration in mg/mmol). In the fully adjusted model, the HR for all ischemic strokes was 1.56 (95% CI 1.24-1.95) for those with an ACR ≥3 mg/mmol compared to participants with an ACR < 1 mg/mmol. Overall, increasing ACR was associated with a higher risk of all ischemic stroke subtypes. This was seen to be strongest for lacunar stroke (HR 1.75, CI 1.12-2.72, p = 0.019), and also for stroke of undetermined etiology (HR 1.53, CI 1.11-2.11, p = 0.009) and those caused by atherosclerosis in the large arteries (HR 1.51, CI 0.78-2.94, p = 0.186) than for cardio-embolic stroke (HR 1.22, CI 0.64-2.3, p = 0.518).

CONCLUSIONS

Albuminuria is an important risk factor, potentially already at low grade, for ischemic stroke especially for lacunar subtype. Measuring albuminuria is both cheap and readily available. This offers the opportunity to evaluate the risk for endothelial dysfunction and thus the subsequent risk for stroke and cerebral small vessel disease.

Cardiovascular and renal protective role of angiotensin blockade in hypertension with advanced CKD: a subgroup analysis of ATTEMPT-CVD randomized trial

The ATTEMPT-CVD study was prospective randomized active-controlled trial and the main findings had been reported. According to baseline GFR and albuminuria categories, we divided the patients of the ATTEMPT-CVD study into 2 subgroups: (Group 1) the patients with at least one of eGFR of <45 ml/min per 1.73 m2 and UACR of ≥300 mg/g creatinine, defined as G3b and/or A3; (Group 2) the patients except for Group 1, defined as the other patients. In patients with G3b and/or A3, the incidence of cardiovascular events was significantly less in ARB group than in non-ARB group (11 vs 22, respectively) (HR = 0.465: 95%CI = 0.224-0.965; P = 0.040). UACR was significantly less in ARB group than in non-ARB group during follow-up period in patients with G3b and/or A3 (P = 0.0003), while eGFR, plasma BNP levels, and blood pressure were comparable between ARB and non-ARB groups. Allocation to ARB therapy was a significant independent prognostic factor for cardiovascular events in patients with G3b and/or A3 (P = 0.0268). On the other hand, in the other patients, the occurrence of cardiovascular events was comparable between ARB and non-ARB groups. In patients with advanced CKD, ARB-based therapy may confer greater benefit in prevention of cardiovascular events than non-ARB therapy.

Short-term effects of the DASH diet in adults with moderate chronic kidney disease: a pilot feeding study

Background

Although the Dietary Approaches to Stop Hypertension (DASH) diet lowers blood pressure (BP) for adults with normal kidney function, evidence is lacking regarding its safety and efficacy in chronic kidney disease (CKD). We aimed to test the effects of the DASH diet on serum electrolytes and BP in adults with moderate CKD.

Methods

In a prospective before–after feeding study, 11 adults with an estimated glomerular filtration rate of 30–59 mL/min/1.73 m² and medication-treated hypertension were provided a reduced-sodium, run-in diet for 1 week followed by a reduced-sodium, DASH diet for 2 weeks. Changes in serum electrolytes and BP were compared pre–post DASH.

Results

Eleven participants underwent feeding; 1 completed 1 week and 10 completed 2 weeks of DASH. Compared with baseline, DASH modestly increased serum potassium at 1 week (mean ± standard deviation, +0.28 ± 0.4 mg/dL; P = 0.043) but had no significant effect on potassium at 2 weeks (+0.15 ± 0.28 mg/dL; P = 0.13). Serum bicarbonate was reduced (−2.5 ± 3.0 mg/dL; P = 0.03) at 2 weeks. Neither incident hyperkalemia nor new onset metabolic acidosis was observed. Clinic BP and mean 24-h ambulatory BP was unchanged. DASH significantly reduced mean nighttime BP (−5.3 ± 5.8 mmHg; P = 0.018), and enhanced percent declines in both nocturnal systolic BP (−2.1% to −5.1%; P = 0.004) and diastolic BP (−3.7% to −10.0%; P = 0.008).

Conclusions

These pilot data suggest that a reduced-sodium DASH dietary pattern does not cause acute metabolic events in adults with moderate CKD and may improve nocturnal BP. Definitive studies are needed to determine long-term effects of DASH in CKD.