Strengthening Instrumental Variables through Weighting

Instrumental variable (IV) methods are widely used to deal with the issue of unmeasured confounding and are becoming popular in health and medical research. IV models are able to obtain consistent estimates in the presence of unmeasured confounding, but rely on assumptions that are hard to verify and often criticized. An instrument is a variable that influences or encourages individuals toward a particular treatment without directly affecting the outcome. Estimates obtained using instruments with a weak influence over the treatment are known to have larger small-sample bias and to be less robust to the critical IV assumption that the instrument is randomly assigned. In this work, we propose a weighting procedure for strengthening the instrument while matching. Through simulations, weighting is shown to strengthen the instrument and improve robustness of resulting estimates. Unlike existing methods, weighting is shown to increase instrument strength without compromising match quality. We illustrate the method in a study comparing mortality between kidney dialysis patients receiving hemodialysis or peritoneal dialysis as treatment for end stage renal disease

Evaluating center performance in the competing risks setting: Application to outcomes of wait‐listed end‐stage renal disease patients

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142886/1/biom12739_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142886/2/biom12739.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142886/3/biom12739-sup-0001-SuppData.pd

Особенности учета расходов и доходов, и их влияние на финансовый результат деятельности субъекта хозяйствования

Основная цель статьи - раскрыть специфику отражения на счетах бухгалтерского учета расходов, доходов и определить их влияние на формирование финансового результата от операционной, финансовой или инвестиционной деятельности.Основна мета статті - розкрити специфіку віддзеркалення на рахунках бухгалтерського обліку витрат, доходів і визначити їх вплив на формування фінансового результату від операційної, фінансової або інвестиційної діяльності

A Pairwise Likelihood Augmented Estimator for the Cox Model Under Left-Truncation

Survival data collected from prevalent cohorts are subject to left-truncation and the analysis is challenging. Conditional approaches for left-truncated data under the Cox model are inefficient as they typically ignore the information in the marginal likelihood of the truncation times. Length-biased sampling methods can improve the estimation efficiency but only when the stationarity assumption of the disease incidence holds, i.e., the truncation distribution is uniform; otherwise they may generate biased estimates. In this paper, we propose a semi-parametric method for the Cox model under general left-truncation, where the truncation distribution is unspecified. Our approach is to make inference based on the conditional likelihood augmented with a pairwise likelihood which eliminates the unspecified truncation distribution, yet retains the information about the regression coefficients and the baseline hazard function in the marginal likelihood. An iterative algorithm is provided to solve for the regression coefficients and the baseline hazard simultaneously. The proposed estimator is consistent and asymptotically normal with a closed-form consistent variance estimator. Simulations show a substantial efficiency gain in both the regression coefficients and the cumulative baseline hazard over the conditional approach estimator. Even when the stationarity assumption holds, our estimator results in better efficiency than some length-biased sampling estimators. An application to the analysis of a chronic kidney disease cohort study illustrates the utility of the method

Study on flame retardant properties of poly(lactic acid) fibre fabrics

Polylactic acid  and its blended yarns with various fibres have been converted in to woven fabrics. These fabric samples have been scoured and then tested for mechanical and flame retardant properties. The results indicate that the high alkaline scouring severely damages polylactic acid fibre. Therefore, mild alkaline scouring is done for further studies. The scoured fabric samples are tested for various flame retardant properties and compared with polyester blended fabrics. Results indicate that polylactic acid fibre is not suitable for upholstery, apparel and work wear in terms of flame retardant properties

Outpatient High‐Dose Urokinase Infusion Improves Dialysis Catheter Longevity: A Prospective Observational Study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134242/1/hdi20004132.pd

Body mass index change and estimated glomerular filtration rate decline in a middle-aged population: health check-based cohort in Japan

Background: Obesity is a growing public health problem worldwide. We evaluated the mediators and association between changes in obesity metrics and renal outcomes in the general population. Methods: Using the Japanese nationwide health check-based cohort from April 2011 to March 2019, we selected individuals aged 40–74 years, with a baseline estimated glomerular filtration rate (eGFR) ≥45 mL/min/1.73 m2, whose body mass index (BMI) change was assessed. The primary outcome was combined 30% decline in eGFR, eGFR 4%) mediated by three risk factors (blood pressure, haemoglobin A1c and total cholesterol), was 13.3%. Conclusion: In the middle-aged Japanese population, both, increase and decrease in BMI were associated with subsequent eGFR decline. Changes in risk factors mediated a small proportion of the association between BMI increase and eGFR decline. Our findings support the clinical significance of monitoring BMI as a renal risk factor

Dietary acid load and chronic kidney disease among adults in the United States

Abstract Background Diet can markedly affect acid-base status and it significantly influences chronic kidney disease (CKD) and its progression. The relationship of dietary acid load (DAL) and CKD has not been assessed on a population level. We examined the association of estimated net acid excretion (NAEes) with CKD; and socio-demographic and clinical correlates of NAEes. Methods Among 12,293 U.S. adult participants aged >20 years in the National Health and Nutrition Examination Survey 1999–2004, we assessed dietary acid by estimating NAEes from nutrient intake and body surface area; kidney damage by albuminuria; and kidney dysfunction by eGFR < 60 ml/min/1.73m2 using the MDRD equation. We tested the association of NAEes with participant characteristics using median regression; while for albuminuria, eGFR, and stages of CKD we used logistic regression. Results Median regression results (β per quintile) indicated that adults aged 40–60 years (β [95% CI] = 3.1 [0.3–5.8]), poverty (β [95% CI] = 7.1 [4.01–10.22]), black race (β [95% CI] = 13.8 [10.8–16.8]), and male sex (β [95% CI] = 3.0 [0.7- 5.2]) were significantly associated with an increasing level of NAEes. Higher levels of NAEes compared with lower levels were associated with greater odds of albuminuria (OR [95% CI] = 1.57 [1.20–2.05]). We observed a trend toward greater NAEes being associated with higher risk of low eGFR, which persisted after adjustment for confounders. Conclusion Higher NAEes is associated with albuminuria and low eGFR, and socio-demographic risk factors for CKD are associated with higher levels of NAEes. DAL may be an important target for future interventions in populations at high risk for CKD.http://deepblue.lib.umich.edu/bitstream/2027.42/109474/1/12882_2014_Article_829.pd