Spectral characteristics of urine from patients with end-stage kidney disease analyzed using Raman Chemometric Urinalysis (Rametrix).

Raman Chemometric Urinalysis (RametrixTM) was used to discern differences in Raman spectra from (i) 362 urine specimens from patients receiving peritoneal dialysis (PD) therapy for end-stage kidney disease (ESKD), (ii) 395 spent dialysate specimens from those PD therapies, and (iii) 235 urine specimens from healthy human volunteers. RametrixTM analysis includes spectral processing (e.g., truncation, baselining, and vector normalization); principal component analysis (PCA); statistical analyses (ANOVA and pairwise comparisons); discriminant analysis of principal components (DAPC); and testing DAPC models using a leave-one-out build/test validation procedure. Results showed distinct and statistically significant differences between the three types of specimens mentioned above. Further, when introducing "unknown" specimens, RametrixTM was able to identify the type of specimen (as PD patient urine or spent dialysate) with better than 98% accuracy, sensitivity, and specificity. RametrixTM was able to identify "unknown" urine specimens as from PD patients or healthy human volunteers with better than 96% accuracy (with better than 97% sensitivity and 94% specificity). This demonstrates that an entire Raman spectrum of a urine or spent dialysate specimen can be used to determine its identity or the presence of ESKD by the donor.

Spectral characteristics of urine specimens from healthy human volunteers analyzed using Raman chemometric urinalysis (Rametrix).

Raman chemometric urinalysis (Rametrix™) was used to analyze 235 urine specimens from healthy individuals. The purpose of this study was to establish the "range of normal" for Raman spectra of urine specimens from healthy individuals. Ultimately, spectra falling outside of this range will be correlated with kidney and urinary tract disease. Rametrix™ analysis includes direct comparisons of Raman spectra but also principal component analysis (PCA), discriminant analysis of principal components (DAPC) models, multivariate statistics, and it is available through GitHub as the Rametrix™ LITE Toolbox for MATLAB®. Results showed consistently overlapping Raman spectra of urine specimens with significantly larger variances in Raman shifts, found by PCA, corresponding to urea, creatinine, and glucose concentrations. A 2-way ANOVA test found that age of the urine specimen donor was statistically significant (p < 0.001) and donor sex (female or male identification) was less so (p = 0.0526). With DAPC models and blind leave-one-out build/test routines using the Rametrix™ PRO Toolbox (also available through GitHub), an accuracy of 71% (sensitivity = 72%; specificity = 70%) was obtained when predicting whether a urine specimen from a healthy unknown individual was from a female or male donor. Finally, from female and male donors (n = 4) who contributed first morning void urine specimens each day for 30 days, the co-occurrence of menstruation was found statistically insignificant to Rametrix™ results (p = 0.695). In addition, Rametrix™ PRO was able to link urine specimens with the individual donor with an average of 78% accuracy. Taken together, this study established the range of Raman spectra that could be expected when obtaining urine specimens from healthy individuals and analyzed by Rametrix™ and provides the methodology for linking results with donor characteristics.

The relationship between glomerular filtration rate and survival in patients treated with an implantable cardioverter defibrillator.

OBJECTIVES: We explored the association between renal insufficiency (RI) and mortality among patients treated with an implantable cardioverter defibrillator (ICD). BACKGROUND: Randomized trials have shown improvements in survival among select patients treated with an ICD. Renal insufficiency patients have a high risk of cardiac death; however, it is not clear whether the ICD has a positive effect on survival in this group of patients. METHODS: This was a retrospective review of a single-center experience of 346 patients treated with an ICD. Patients were stratified into 4 groups according to their glomerular filtration rate (eGFR; expressed as mL/min/ -1.73 m(2)) at implantation: group I, > 75.0; group II, - 60.0 to 74.9; group III, - 45.0 to 59.9; and group IV, - < or = 45.0. All-cause mortality was the primary end point, with differences in survival times among the 4 groups of patients expressed in Kaplan-Meier curves. RESULTS: Mean follow-up was 3.5 y (range 0.1 to 12.9 y), during which 67 patients died (19%). Mortality in each eGFR group was: I - 6.8%, II - 13.8%, III - 11.5%, IV - 45.8% (p < 0.001). Survival times (mean, y) were I, 3.74; II, 3.66; III, 3.38, and IV, 2.82. The presence of diabetes was not a factor in the outcomes. CONCLUSIONS: Patients treated with an ICD with an eGFR of < or = 45.0 mL/min/1.73 m(2) have a significantly shorter survival time than those patients with an eGFR > 45.0 mL/min/1.73 m(2). Patients with an eGFR > 45.0 mL/min/1.73 m(2) appear to have equally good outcomes when treated with an ICD. This may have implications for patient selection for ICD therapy.

Temporal effects of dialysis on cognitive functioning in patients with ESRD.

BACKGROUND: Although dialysis has been shown to improve cognitive deficits resulting from uremia, little is known about potential temporal variations in cognitive measures between hemodialysis treatments. METHODS: We studied dialysis patients for possible fluctuations in attention and memory by using repeatable neuropsychological measures. Twenty patients undergoing hemodialysis on a thrice-weekly dialysis schedule were assessed at intervals of 1, 24, and 67 hours after the last weekly hemodialysis session. For purposes of comparison, we also studied 10 patients on continuous ambulatory peritoneal dialysis (CAPD) therapy at similar intervals. RESULTS: CAPD patients showed overall stable performance on measures of attention and memory. However, hemodialysis patients showed significant changes (P < 0.05) in auditory memory for both immediate and delayed recall, with the greatest impairment occurring 67 hours postdialysis. Hemodialysis patients also showed a significant change (P < 0.05) in attention between the second and third test periods, ie, 24 to 67 hours postdialysis, with the greatest impairment seen at the 67-hour assessment time. No relationship was found between performance on measures of cognition and levels of postdialysis fatigue in hemodialysis patients. CONCLUSION: CAPD patients showed cognitive stability, whereas hemodialysis patients showed temporal fluctuations in cognitive performance.

Adjustment of hemodialysis dose for residual renal urea clearance: a two year study of impact on dialysis time.

Urea kinetic modeling suggests that significant time reductions may be realized in hemodialysis patients with residual renal urea clearance (K(r)t/V urea). However, the actual impact of a strategy that integrates such function into the dialysis prescription is not clear, because of both uncertainty regarding the rate of decay of K(r)t/V urea, as well as potential clinical constraints upon dose reduction. To examine this issue, we retrospectively reviewed data from 51 patients with K(r)t/N urea after initiation of maintenance hemodialysis. In 31 cases, there were no clinical barriers to adjustment of the dialysis prescriptions. Regression analysis revealed that each 0.10 increment in K(r)t/V urea yielded an actual dialysis time reduction of 12 minutes per week with average cumulative reduction of 80 minutes per week per patient. At approximately 1 year after initiation of dialysis, there were still 10 patients whose dialysis prescriptions were being adjusted on the basis of K(r)t/V urea. In conclusion, our results suggest that the incorporation of K(r)t/V urea in the hemodialysis prescription allows for substantial and enduring reductions in dialysis time in a significant minority of patients. Larger prospective studies are needed to evaluate the long-term safety of this strategy in modifying the dose of hemodialysis.