The association of functional status with mortality and dialysis modality change : results from the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS)

BACKGROUND: Little is known about the prevalence of functional impairment in peritoneal dialysis (PD) patients, its variation by country, and its association with mortality or transfer to hemodialysis. METHODS: A prospective cohort study was conducted in PD patients from 7 countries in the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) (2014 - 2017). Functional status (FS) was assessed by combining self-reports of 8 instrumental and 5 basic activities of daily living, using the Lawton-Brody and the Katz questionnaires. Summary FS scores, ranging from 1.25 (most dependent) to 13 (independent), were based on the patient's ability to perform each activity with or without assistance. Logistic regression was used to estimate the odds ratio (OR; 95% confidence interval [CI]) of a FS score < 11 comparing each country with the United States (US). Cox regression was used to estimate the hazard ratio (HR; 95% CI) for the effect of a low FS score on mortality and transfer to hemodialysis, adjusting for case mix. RESULTS: Of 2,593 patients with complete data on FS, 48% were fully independent (FS = 13), 32% had a FS score 11 to < 13, 14% had a FS score 8 to < 11, and 6% had a FS score < 8. Relative to the US, low FS scores (< 11; more dependent) were more frequent in Thailand (OR = 10.48, 5.90 - 18.60) and the United Kingdom (UK) (OR = 3.29, 1.77 - 6.08), but similar in other PDOPPS countries. The FS score was inversely and monotonically associated with mortality but not with transfer to hemodialysis; the HR, comparing a FS score < 8 vs 13, was 4.01 (2.44 - 6.61) for mortality and 0.91 (0.58 - 1.43) for transfer to hemodialysis. CONCLUSION: Regional differences in FS scores observed across PDOPPS countries may have been partly due to differences in regional patient selection for PD. Functional impairment was associated with mortality but not with permanent transfer to hemodialysis

Efficient Adaptive Algorithms for ARX Identification

In this paper two efficient adaptive algorithmic families are developed for multichannel combiners characterized by unequal memory lengths for each input channel. The prewindowed, the covariance, as well as the sliding window case are treated. The new algorithms are based on two different updating procedures for the associated Kalman gain vector by employing suitable permutation matrices. Both algorithms are applicable to adaptive ARX system identification, to adaptive control, and to the design of decision-feedback equalizers. Simulations are included. © 1991 IEE

An efficient method for multipath channel equalization

In this paper efficient batch and adaptive algorithms in transversal and lattice forms multipath propagation are developed. Linear interpolation is employed to establish that multipath channel equalizers are adequately represented by autoregressive filters provided the transmitted signal is PAM modulated with raised-cosine frequency characteristics. A highly concurrent block algorithm suitable for VLSI implementation is developed. Moreover a fast sliding window covariance type adaptive algorithm aimed to track rapid multipath channel variations is derived. Simulation results are included. © 1989

Beamforming capacity optimization for rician MIMO wireless channels

The beamformer that maximizes the ergodic beamforming capacity under correlated (or uncorrelated with non-unit covariance matrix) Rician MISO channels can be calculated in the context of a simple one-dimensional optimization problem, according to the solution proposed in. The present work extends this concept and provides a new simple and practically feasible solution for the corresponding Rician MIMO propagation channels. Simulation results demonstrate that: a. the optimum beamformer further improves capacity compared to the max SNR Beamformer, b. the proposed one-dimensional search method that is employed to solve the optimum beamforming problem has significantly lower computational complexity compared to currently used (multi-dimensional) algorithms. © 2012 IEEE

Ergodic capacity optimization for single-stream beamforming transmission in MISO rician fading channels

The maximization of the ergodic capacity for single-stream beamforming, which is a (constrained) transmission scheme referred to as &apos;optimum beamforming,&apos; has been extensively addressed in the open literature for multiple-input-single-output (MISO) Rayleigh fading channels and spatially uncorrelated MISO Rician fading channels with a unit transmit covariance matrix, and closed-form solutions have been derived for these cases. However, optimum beamforming for spatially correlated or uncorrelated MISO Rician fading channels with a nonunit transmit covariance matrix has received less attention and remains a complex multidimensional optimization problem. This paper first proves that this convex constrained optimization problem can be reduced to only one dimension; hence, it can be solved very fast using standard 1-D search algorithms. Then, simulations mainly performed for linear equispaced antenna arrays demonstrate that: 1) the proposed method for the calculation of the optimum beamformer has significantly lower computational complexity compared with other currently used multidimensional algorithms; and 2) the optimum beamformer further improves capacity compared with the (single-stream) beamforming transmission that maximizes the signal-to-noise ratio (SNR) at the receiver, whereas in some operational environments, it achieves ergodic capacity that is very close or equal to the maximum ergodic capacity. © 1967-2012 IEEE

Receiving hemodialysis in Hispanic ethnic dense communities is associated with better adherence and outcomes among young patients: a retrospective analysis of the Dialysis Outcomes and Practice Patterns Study

Abstract Background Hispanic ethnic density (HED) is a marker of better health outcomes among Hispanic patients with chronic disease. It is unclear whether community HED is associated with mortality risk among ethnically diverse patients receiving maintenance hemodialysis. Methods A retrospective analysis of patients in the United States cohort of the Dialysis Outcomes and Practice Patterns Study (DOPPS) database (2011–2015) was conducted (n = 4226). DOPPS data was linked to the American Community Survey database by dialysis facility zip code to obtain % Hispanic residents (HED). One way ANOVA and Kruskal Wallis tests were used to estimate the association between tertiles of HED with individual demographic, clinical and adherence characteristics, and facility and community attributes. Multivariable Cox proportional hazards models were used to estimate the mortality hazard ratio (HR) and 95% CIs by tertile of HED, stratified by age; a sandwich estimator was used to account for facility clustering. Results Patients dialyzing in facilities located in the highest HED tertile communities were younger (61.4 vs. 64.4 years), more commonly non-White (62.4% vs. 22.1%), had fewer comorbidities, longer dialysis vintage, and were more adherent to dialysis treatment, but had fewer minutes of dialysis prescribed than those in the lowest tertile. Dialyzing in the highest HED tertile was associated with lower hazard of mortality (HR, 0.86; 95% CI, 0.72-1.00), but this association attenuated with the addition of individual race/ethnicity (HR, 0.92; 95% CI, 0.78–1.09). In multivariable age-stratified analyses, those younger than 64 showed a lower hazard for mortality in the highest (vs. lowest) HED tertile (HR, 0.66; 95% CI, 0.49–0.90). Null associations were observed among patients ≥ 64 years. Conclusions Treating in communities with greater HED and racial/ethnic integration was associated with lower mortality among younger patients which points to neighborhood context and social cohesion as potential drivers of improved survival outcomes for patients receiving hemodialysis