Stratifying risk in chronic kidney disease: an observational study of UK guidelines for measuring total proteinuria and albuminuria.

BACKGROUND: Proteinuria predicts poor renal and cardiovascular outcomes. Some guidelines recommend measuring proteinuria using albumin:creatinine ratio (ACR), while others recommend total protein:creatinine ratio (TPCR). AIM: To compare renal outcomes and mortality in the populations identified by these different recommendations. DESIGN: Retrospective longitudinal cohort study. METHODS: Baseline ACR and TPCR measurements were obtained from 5586 patients with chronic kidney disease (CKD) attending a Scottish hospital nephrology clinic. The cohort was divided into three groups with concordant results by ACR and TPCR (no proteinuria; low proteinuria; significant proteinuria) and one group with discordant results (significant proteinuria with TPCR, but not ACR). Outcomes were assessed using Kaplan-Meier plots and Cox proportional hazards models. RESULTS: Median follow-up was 3.5 years [interquartile range (IQR) 2.1-6.0]; 844 (15%) died at 3.0 years (IQR 1.8-4.7) and 468 (8%) started renal replacement therapy (RRT) at 1.7 years (IQR 0.6-3.4). Proteinuria was associated with a substantially increased risk of RRT and death. Patients with significant proteinuria by TPCR, but not ACR (n = 231) had high renal risk, and the highest all-cause mortality (log-rank P < 0.001). With multivariate analysis the risk fell below those with significant proteinuria with concordant results by ACR and TPCR but remained considerably higher than those without significant proteinuria. CONCLUSION: Proteinuria screening with TPCR identifies an additional 16% of patients with significant proteinuria, not identified using ACR. This subgroup has high renal risk, and high risk of all-cause mortality and therefore warrant identification. Guideline recommendations on proteinuria screening in CKD should be reconsidered.

Free radical activity and lipid soluble anti-oxidant vitamin status in patients with long-term ileal pouch-anal anastomosis.

OBJECTIVE: Ileal pouch-anal anastomosis (IPAA) is the operation of choice for patients with ulcerative colitis. Free radical activity and the status of lipid soluble antioxidant vitamins have not been previously assessed in patients with IPAA. The aim of the present study was to measure the plasma concentrations of lipophyllic antioxidants and free radical activity in IPAA patients and compare them with normal subjects. METHOD: Forty-eight IPAA patients and 50 healthy controls were studied. A dietary assessment of vitamin E (alpha-tocopherol) and carotene was undertaken and plasma antioxidant status was assessed. Plasma malondialdehyde (MDA) was measured to assess the extent of free radical damage. In IPAA patients, association between the degree of inflammation in the pouch mucosa and the plasma concentration of lipophyllic antioxidants and extent of free radical activity was investigated. RESULTS: The dietary intake of carotene was similar in both groups. Intake of vitamin E was significantly lower in patients than controls (P = 0.01). In the IPAA group plasma concentrations of alpha-carotene, beta-carotene and lycopene were significantly lower (P < 0.001) and alpha-tocopherol:cholesterol ratio significantly higher (P < 0.001). Free radical damage was significantly greater in patients than controls (P < 0.01). There were no significant correlations between the degree of inflammation in the pouch and plasma concentrations of MDA, carotenoids, alpha-tocopherol:cholesterol ratio or intake of vitamins. CONCLUSION: Compared with normal subjects, patients with IPAA have significantly lower plasma concentrations of lipophyllic antioxidants alpha-carotene, beta-carotene and lycopene and higher free radical activity suggesting increased oxidative stress. These differences do not appear to be related to diet and do not correlate with histological severity of pouch inflammation.