Project description:Rationale & objectiveDetermining whether a change in estimated glomerular filtration rate (eGFR) or albuminuria is clinically significant requires knowledge of short-term within-person variability of the measurements, which few studies have addressed in the setting of chronic kidney disease.Study designCross-sectional study with multiple collections over less than 4 weeks.Setting & participantsClinically stable outpatients with chronic kidney disease (N=50; mean age, 56.8 years; median eGFR, 40mL/min/1.73m2; median urinary albumin-creatinine ratio (UACR), 173mg/g).ExposureRepeat measurements from serially collected samples across 3 study visits.OutcomesMeasurements of urine albumin concentration (UAC), UACR, and plasma creatinine, cystatin C, β2-microglobulin (B2M), and beta trace protein (BTP).Analytical approachWe calculated within-person coefficients of variation (CVw) values and corresponding reference change positive and negative (RCVpos and RCVneg) values using log-transformed measurements.ResultsMedian CVw (RCVpos; RCVneg) values of filtration markers were 5.4% (+16%; -14%) for serum creatinine, 4.1% (+12%; -11%) for cystatin C, 7.4% (+23%; -18%) for BTP, and 5.6% (+17%; -14%) for B2M. Results for albuminuria were 33.2% (+145%; -59%) for first-morning UAC, 50.6% (+276%; -73%) for random spot UAC, 32.5% (+141%; -58%) for first-morning UACR, and 29.7% (124%; -55%) for random spot UACR. CVw values for filtration markers were comparable across the range of baseline eGFRs. CVw values for UAC and UACR were comparable across the range of baseline albuminuria values.LimitationsSmall sample size limits the ability to detect differences in variability across markers. Participants were recruited and followed up in a clinical and not research setting, so some preanalytical factors could not be controlled.ConclusionseGFR markers appear to have relatively low short-term within-person variability, whereas variability in albuminuria appears to be high, making it difficult to distinguish random variability from meaningful biologic changes.
Project description:Higher levels of albuminuria associate with increased risk for adverse outcomes independent of estimated GFR (eGFR), but whether albuminuria also associates with concurrent complications specific to chronic kidney disease (CKD) is unknown. Here, we assessed the association of spot albumin-to-creatinine ratio with anemia, acidosis, hyperphosphatemia, hypoalbuminemia, hyperparathyroidism, and hypertension among 30,528 adult participants in NHANES 1988-1994 and 1999-2006. After multivariable adjustment including eGFR, higher albumin-to-creatinine ratios associated with anemia, acidosis, hypoalbuminemia, hyperparathyroidism, and hypertension but only weakly associated with acidosis and anemia. Furthermore, the associations between albumin-to-creatinine ratio and both anemia and acidosis were not consistent across eGFR strata. Higher albumin-to-creatinine ratio levels did not associate with hyperphosphatemia. Lower eGFR associated with higher prevalence ratios for all complications, and these associations were stronger than those observed for the albumin-to-creatinine ratio; after multivariable adjustment, however, the associations between eGFR and both hypoalbuminemia and hypertension were NS. In conclusion, albuminuria and eGFR differentially associate with complications of CKD.
Project description:BACKGROUND AND OBJECTIVES:The microvascular circulation plays an important role in bone health. This study examines whether albuminuria, a marker of renal microvascular disease, is associated with incident hip and pelvic fractures. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:This study reanalyzed data from the Ongoing Telmisartan Alone and in combination with Ramipril Global End Point Trial/Telmisartan Randomized Assessment Study in Angiotensin-Converting Enzyme Intolerant Subjects with Cardiovascular Disease trials, which examined the impact of renin angiotensin system blockade on cardiovascular outcomes (n=28,601). Albuminuria was defined as an albumin-to-creatinine ratio?30 mg/g (n=4597). Cox proportional hazards models were used to determine the association of albuminuria with fracture risk adjusted for known risk factors for fractures, estimated GFR, and rapid decline in estimated GFR (?5%/yr). RESULTS:There were 276 hip and pelvic fractures during a mean of 4.6 years of follow-up. Participants with baseline albuminuria had a significantly increased risk of fracture compared with participants without albuminuria (unadjusted hazard ratio=1.62 [1.22, 2.15], P<0.001; adjusted hazard ratio=1.36 [1.01, 1.84], P=0.05). A dose-dependent relationship was observed, with macroalbuminuria having a large fracture risk (unadjusted hazard ratio=2.01 [1.21, 3.35], P=0.007; adjusted hazard ratio=1.71 [1.007, 2.91], P=0.05) and microalbuminuria associating with borderline or no statistical significance (unadjusted hazard ratio=1.52 [1.10, 2.09], P=0.01; adjusted hazard ratio=1.28 [0.92, 1.78], P=0.15). Estimated GFR was not a predictor of fracture in any model, but rapid loss of estimated GFR over the first 2 years of follow-up predicted subsequent fracture (adjusted hazard ratio=1.47 [1.05, 2.04], P=0.02). CONCLUSIONS:Albuminuria, especially macroalbuminuria, and rapid decline of estimated GFR predict hip and pelvic fractures. These findings support a theoretical model of a relationship between underlying causes of microalbuminuria and bone disease.
Project description:Background and objectivesWhether combining changes in eGFR and urine albumin-to-creatinine ratio (UACR) is more strongly associated with outcomes compared with either change alone is unknown.Design, setting, participants, & measurementsWe analyzed 8766 patients with type 2 diabetes in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation Observational (ADVANCE-ON) study. Changes in eGFR and UACR (baseline to 2 years) were defined as ≥40% decrease, minor change, and ≥40% increase. The primary outcome was the composite of major macrovascular (nonfatal or fatal myocardial infarction, nonfatal or fatal stroke, or cardiovascular death), major kidney events (requirement for kidney replacement therapy or kidney death), and all-cause mortality.ResultsOver a median of 7.7 years of follow-up, 2191 primary outcomes were recorded. Strong linear associations between eGFR and UACR changes and subsequent risk of the outcome were observed. For eGFR, the hazard ratios were 1.58 (95% confidence interval [95% CI], 1.27 to 1.95) for a decrease ≥40% and 0.82 for an increase ≥40% (95% CI, 0.64 to 1.04) compared with minor change. For UACR, the hazard ratios were 0.96 (95% CI, 0.85 to 1.07) for a decrease ≥40% and 1.32 (95% CI, 1.19 to 1.46) for ≥40% increase compared with minor change. Compared with dual minor changes, both an eGFR decrease ≥40% and a UACR increase ≥40% had 2.31 (95% CI, 1.67 to 3.18) times the risk of the outcome, with evidence of interaction between the two markers.ConclusionsClinically meaningful decreases in eGFR and increases in UACR over 2 years, independently and in combination, were significantly associated with higher risk of major clinical outcomes.
Project description:BackgroundBone fragility fractures are associated with high morbidity and mortality. This study analysed the association between the current biochemical parameters of CKD-MBD and bone fragility fractures in the COSMOS project.MethodsCOSMOS is a 3-year, multicentre, open cohort, prospective, observational study carried out in 6797 hemodialysis patients (227 centres from 20 European countries). The association of bone fragility fractures (outcome) with serum calcium, phosphate and PTH (exposure), was assessed using Standard Cox proportional hazards regression and Cox proportional hazards regression for recurrent events. Additional analyses were performed considering all-cause mortality as a competitive event for bone fragility fracture occurrence. Multivariable models were used in all strategies, with the fully adjusted model including a total of 24 variables.ResultsDuring a median follow-up of 24 months 252 (4%) patients experienced at least one bone fragility fracture (incident bone fragility fracture rate 28.5 per 1000 patient-years). In the fractured and non-fractured patients, the percentage of men was 43.7% and 61.4%, mean age 68.1 and 63.8 years and a haemodialysis vintage of 55.9 and 38.3 months respectively. Baseline serum phosphate > 6.1 mg/dL (reference value 4.3-6.1 mg/dL) was significantly associated with a higher bone fragility fracture risk in both regression models (HR: 1.53[95%CI: 1.10-2.13] and HR: 1.44[95%CI: 1.02-2.05]. The significant association persisted after competitive risk analysis (subHR: 1.42[95%CI: 1.02-1.98]) but the finding was not confirmed when serum phosphate was considered as a continuous variable. Baseline serum calcium showed no association with bone fragility fracture risk in any regression model. Baseline serum PTH > 800 pg/mL was significantly associated with a higher bone fragility fracture risk in both regression models, but the association disappeared after a competitive risk analysis.ConclusionsHyperphosphatemia was independently and consistently associated with an increased bone fracture risk, suggesting serum phosphate could be a novel risk factor for bone fractures in hemodialysis patients.
Project description:Both a low estimated glomerular filtration rate (eGFR) and albuminuria are known risk factors for end-stage renal disease (ESRD). To determine their joint contribution to ESRD and other kidney outcomes, we performed a meta-analysis of nine general population cohorts with 845,125 participants and an additional eight cohorts with 173,892 patients, the latter selected because of their high risk for chronic kidney disease (CKD). In the general population, the risk for ESRD was unrelated to eGFR at values between 75 and 105 ml/min per 1.73 m(2) but increased exponentially at lower levels. Hazard ratios for eGFRs averaging 60, 45, and 15 were 4, 29, and 454, respectively, compared with an eGFR of 95, after adjustment for albuminuria and cardiovascular risk factors. Log albuminuria was linearly associated with log ESRD risk without thresholds. Adjusted hazard ratios at albumin-to-creatinine ratios of 30, 300, and 1000 mg/g were 5, 13, and 28, respectively, compared with an albumin-to-creatinine ratio of 5. Albuminuria and eGFR were associated with ESRD, without evidence for multiplicative interaction. Similar associations were found for acute kidney injury and progressive CKD. In high-risk cohorts, the findings were generally comparable. Thus, lower eGFR and higher albuminuria are risk factors for ESRD, acute kidney injury and progressive CKD in both general and high-risk populations, independent of each other and of cardiovascular risk factors.
Project description:Rationale & objectiveEvidence is limited on how estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) relate to dementia at different ages. We evaluated eGFR and UACR in midlife and older age as risk factors for dementia. Additionally, we assessed whether the association between eGFR and dementia is altered when cystatin C and β2-microglobulin (B2M) levels are used for GFR estimation.Study designProspective cohort study.Setting & participantsTwo baselines from the Atherosclerosis Risk in Communities (ARIC) Study were used: visit 4 (1996-1998), including 9,967 participants 54 to 74 years old, and visit 5 (2011-2013), including 4,626 participants 70 to 90 years old. Participants were followed up until 2017.PredictorsLog(UACR); eGFR based on creatinine, cystatin C, creatinine and cystatin C, or B2M levels (denoted as eGFRcr, eGFRcys, eGFRcr-cys, and eGFRB2M).OutcomeIncident dementia.Analytical approachMultivariable Cox proportional hazards regression models fit separately for each of the 5 predictors and based on a change in the predictor equivalent to the interquartile range for that predictor at visit 4 (IQRV4). eGFR models were adjusted for log(UACR) and log(UACR) models were adjusted for eGFRcys.ResultsWe observed 1,821 dementia cases after visit 4 and 438 cases after visit 5. Dementia risk increased with higher albuminuria levels (HRs per IQRV4 [equivalent to 4.2-fold greater log albuminuria] of 1.15 [95% CI, 1.09-1.21] after visit 4 and 1.27 [95% CI, 1.13-1.42] after visit 5). An association with lower eGFR was seen for only eGFRcys (HRs per IQRV4 [equivalent to 24.3mL/min/1.73m2 lesser eGFRcys] of 1.12 [95% CI, 1.04-1.21] after visit 4 and 1.30 [95% CI, 1.12-1.52] after visit 5) and eGFRB2M (HRs per IQRV4 [equivalent to 18.3mL/min/1.73m2 lesser eGFRB2M] of 1.15 [95% CI, 1.07-1.23] after visit 4 and 1.34 [95% CI, 1.17-1.55] after visit 5). Differences between these associations in midlife and older age were not statistically significant.LimitationsChanges in potentially time-varying covariates were not measured. Dementia was not subclassified by cause.ConclusionsAlbuminuria was consistently associated with dementia incidence. Lower eGFR based on cystatin C or B2M, but not creatinine, levels was also associated with dementia. Risk associations were similar when kidney measures were assessed at midlife and older age.
Project description:Rationale & objectiveChronic kidney disease (CKD) is associated with impaired physical performance. However, the association between albuminuria, a marker of vascular endothelial dysfunction, and physical performance has not been fully characterized. We hypothesized that estimated glomerular filtration rate (eGFR) and albuminuria would be independently associated with physical performance.Study designCross-sectional analysis.Setting & participantsA total of 571 adults with and without CKD.PredictorsCreatinine-based eGFR (eGFRCr) and cystatin C-based eGFR (eGFRCysC) and urine albumin to creatinine ratio (UACR).OutcomeShort Physical Performance Battery (SPPB).Analytical approachUnivariate and multivariable logistic regression models were used to examine associations of eGFR and UACR with impaired physical performance.ResultsOf the 571 participants (mean age, 69.3 years), 157 (27.5%) had eGFRCr (mL/min/1.73m2) <30, 276 (48.3%) had eGFRCr 30-<60, and 138 (24.2%) had eGFRCr ≥60; 303 (55.3%) participants had eGFRcysC <30, 141 (25.7%) had eGFRcysC 30-<60, and 104 (19.0%) had eGFRcysC ≥60. Impaired physical performance was observed in 222 (38.9%) participants. Separate univariate analyses showed that lower eGFRCr, lower eGFRCysC, and higher UACR were associated with higher odds of impaired physical performance. In the adjusted model with eGFRCr or eGFRCysC, UACR, and covariates, UACR retained a statistically significant association with impaired physical performance (adjusted odds ratio [OR], 2.04; 95% confidence interval [CI], 1.21-3.47 for UACR from 30-300 mg/g vs <30 mg/g and adjusted OR, 1.93; 95% CI, 1.01-3.69 for UACR >300 mg/g vs <30 mg/g), but eGFRCr and eGFRCysC did not.LimitationsCross-sectional analysis, estimated rather than measured GFR.ConclusionsOnly UACR was associated with worse physical performance in the fully adjusted model, suggesting that vascular endothelial function and inflammation may be important mechanisms of decreased physical function. Similar results were found using eGFRCr or eGFRCysC, suggesting that confounding based on muscle mass does not explain the lack of an association between eGFRCr and physical performance.
Project description:BackgroundHIV infection has been associated with an increased risk of fragility fracture. We explored whether or not this increased risk persisted in HIV infected and uninfected men when controlling for traditional fragility fracture risk factors.Methodology/principal findingsCox regression models were used to assess the association of HIV infection with the risk for incident hip, vertebral, or upper arm fracture in male Veterans enrolled in the Veterans Aging Cohort Study Virtual Cohort (VACS-VC). We calculated adjusted hazard ratios comparing HIV status and controlling for demographics and other established risk factors. The sample consisted of 119,318 men, 33% of whom were HIV infected (34% aged 50 years or older at baseline, and 55% black or Hispanic). Median body mass index (BMI) was lower in HIV infected compared with uninfected men (25 vs. 28 kg/m²; p<0.0001). Unadjusted risk for fracture was higher among HIV infected compared with uninfected men [HR: 1.32 (95% CI: 1.20, 1.47)]. After adjusting for demographics, comorbid disease, smoking and alcohol abuse, HIV infection remained associated with an increased fracture risk [HR: 1.24 (95% CI: 1.11, 1.39)]. However, adjusting for BMI attenuated this association [HR: 1.10 (95% CI: 0.97, 1.25)]. The only HIV-specific factor associated with fragility fracture was current protease inhibitor use [HR: 1.41 (95% CI: 1.16, 1.70)].Conclusions/significanceHIV infection is associated with fragility fracture risk. This risk is attenuated by BMI.
Project description:Rare mutations in nephrosis 2 (NPHS2), encoding podocin, are found in patients with familial and sporadic steroid-resistant nephrotic syndrome and focal segmental glomerular sclerosis. The objective of this study is to assess the contribution of the commonly reported functional podocin polymorphism R229Q to kidney disease in the population at large and replicate a prior study of an association of R229Q and albuminuria in the general population.Large sample of the Atherosclerosis Risk in Communities (ARIC) Study, a population-based prospective study.4,424 white and 3,746 black middle-aged adults.Genotype at the R229Q polymorphism in podocin.Urinary albumin-creatinine ratio (ACR) and decreased estimated glomerular filtration rate (eGFR) as measures of kidney damage/dysfunction.Crude and multivariable adjusted linear and logistic regression models.R229Q allele frequencies were 3.7% in 4,424 white and 0.6% in 3,746 black individuals. No significant association of R229Q with increased ACR or decreased eGFR was observed (adjusted odds ratio of ACR > or = 30 mg/g in RQ/QQ versus RR carriers, 1.18; 95% confidence interval, 0.76 to 1.84; adjusted odds ratio of eGFR < 60 mL/min/1.73 m(2) in RQ/QQ versus RR carriers, 1.18; 95% confidence interval, 0.76 to 1.83). As expected, the established kidney disease risk factors hypertension and diabetes mellitus were associated strongly with measures of kidney damage/dysfunction, but the R229Q polymorphism was not associated with an additional increase in kidney disease measures.Single measurement of ACR, subsample of all ARIC participants.No significant association of the relatively rare R229Q variant and ACR or eGFR was found in either white or black individuals. The phenotypic effect of a variant as R229Q would have to be of great magnitude to meaningfully contribute to the risk of kidney disease on a population level. The importance of such variants in the general population, as well as replication studies, can be evaluated best in large community-based studies that allow for accounting of established disease risk factors.