Conventional Levels Of Statistical Significance Research Articles

Residential radon decay products are associated with cough and phlegm in patients with COPD

Radon decay products attach to particulate matter (referred to as particle radioactivity, PR) has been shown to be potential to promote airway damage after inhalation. In this study, we investigated associations between PR with respiratory symptoms and health-related quality of life (HRQL) in patients with COPD. 141 male patients with COPD, former smokers, completed the St. George's Respiratory Questionnaire (SGRQ) after up to four 1-week seasonal assessments (N=474) of indoor (home) and ambient (central site) particulate matter ≤ 2.5 µm in diameter (PM2.5) and black carbon (BC). Indoor PR was measured as α-activity (radiation) on PM2.5 filter samples. The ratio of indoor/ambient sulfur in PM2.5 (a ventilation surrogate) was used to estimate α-PR from indoor radon decay. SGRQ responses assessed frequent cough, phlegm, shortness of breath, wheeze, and chest attacks in the past 3 months. Multivariable linear regression with generalized estimating equations accounting for repeated measures was used to explore associations, adjusting for potential confounders. Median (IQR) indoor α-PR was 1.22 (0.62) mBq/m3. We found that there were positive associations between α-PR with cough and phlegm. The strongest associations were with estimated α-PR of indoor origin for cough (31.1 % increase/IQR, 95 %CI: 8.8 %, 57.8 %), and was suggestive for phlegm (13.0 % increase/IQR, 95 %CI: −2.5 %, 31.0 %), similar adjusting for indoor BC or PM2.5. α-PR of indoor origin was positively associated with an increase in SGRQ Symptoms score [1.2 units/IQR; 95 %CI: −0.3, 2.6] that did not meet conventional levels of statistical significance. Our results suggested that exposure to indoor radon decay products measured as particle radioactivity, a common indoor exposure, is associated with cough, and suggestively associated with phlegm and worse HRQL symptoms score in patients with COPD.

Quarterly Percentual Change in Height, Weight, Body Fat and Muscle Mass in Young Football Players of Different Categories

Quarterly Percentual Change in Height, Weight, Body Fat and Muscle Mass in Young Football Players of Different Categories

The Narrowing Gender Wage Gap Among Faculty at Public Universities in the U.S

We study the conditional gender wage gap among faculty at public research universities in the U.S. We begin by using a cross-sectional dataset from 2016 to replicate the long-standing finding in research that, conditional on rich controls, female faculty earn less than their male colleagues. Next, we construct a data panel to track the evolution of the wage gap through 2021. We show that the gender wage gap is narrowing. It declined by more than 50% over the course of our data panel to the point where by 2021, it is no longer detectable at conventional levels of statistical significance.

Association of weight loss with risk of myelodysplastic syndromes (MDS) in adults with obesity: Insights from the SPLENDID cohort.

e18865 Background: MDS arises from pre-existing somatic mutations or clonal hematopoiesis (CH). A normal body mass index (BMI) is strongly associated with a lower prevalence of CH. We hypothesized that intentional weight loss (IWL) might be associated with lower incidence of MDS and studied this in the context of bariatric surgery (BSx) among adults with obesity. Methods: In the SPLENDID (Surgical Procedures and Long-term Effectiveness in Neoplastic Disease Incidence and Death) matched cohort study, adults with BMI ≥35Kg/m2 who had BSx (ages 18-80) during 2004-2017 were included. Each patient (pt) who underwent BSx was matched with propensity score by the nearest-neighbor method to five pts who did not undergo BSx for their obesity, resulting in a total of 30318 pts. MDS diagnosis was made using contemporary WHO criteria and myeloid sequencing mutation data were analyzed. Multivariable cox regression analysis estimated time to MDS as the primary endpoint. Results: 5053 adults with obesity had BSx while 25265 adults underwent nonsurgical (NS) care. Median age and BMI were 46 years (y) and 45kg/m2. The majority were females (77%); and had white (73%) race. Follow-up was over 17y period with median (IQR) of 6.1 (3.8-8.9)y for the entire cohort. BSx-group had 19.2% greater WL at 10-y [mean between-group difference: 24.8 (95% CI, 24.6-25.1) kg]. One patient (male) in the BSx-group vs twenty-four patients (twelve females) in the NS-group developed MDS (incidence rate: 0.03 vs 0.14, per 1000 person-years). A fully adjusted hazard ratio was 0.14 (95%CI 0.02-1.14), which did not reach conventional level of statistical significance (p = 0.066) due to small number of events. A third of MDS pts had high-risk disease per IPSS-R prognostic score (7/20 evaluable pts). 10 (of 11 NS MDS pts with available NGS data) pts had ≥1 nonsynonymous mutations and most pts (6/11) harbored multiple [Median (IQR): 2 (1-3)] high-risk mutations despite a younger median age of the cohort. Conclusions: In this large cohort of adults with obesity, we observed a lower incidence of MDS after IWL achieved with BSx. Higher prevalence of high-risk-MDS mutations in a relatively young NS-cohort with obesity warrants further investigation of effects of IWL on clonal evolution, its clinical relevance, and role of screening in halting progression of CH to MDS via early detection and targeted intervention. [Table: see text]

On the reliability of published findings using the regression discontinuity design in political science

The regression discontinuity (RD) design offers identification of causal effects under weak assumptions, earning it a position as a standard method in modern political science research. But identification does not necessarily imply that causal effects can be estimated accurately with limited data. In this paper, we highlight that estimation under the RD design involves serious statistical challenges and investigate how these challenges manifest themselves in the empirical literature in political science. We collect all RD-based findings published in top political science journals in the period 2009–2018. The distribution of published results exhibits pathological features; estimates tend to bunch just above the conventional level of statistical significance. A reanalysis of all studies with available data suggests that researcher discretion is not a major driver of these features. However, researchers tend to use inappropriate methods for inference, rendering standard errors artificially small. A retrospective power analysis reveals that most of these studies were underpowered to detect all but large effects. The issues we uncover, combined with well-documented selection pressures in academic publishing, cause concern that many published findings using the RD design may be exaggerated.

Exploratory Evaluation of Neopterin and Chitotriosidase as Potential Circulating Biomarkers for Colorectal Cancer

Chronic inflammation is demonstrated to play a direct role in carcinogenesis. Our exploratory study aimed to assess the potential added value of two inflammation biomarkers, chitotriosidase and neopterin, in follow-up evaluation of patients with colorectal cancer (CRC). An observational exploratory study was conducted. Patients with CRC and matched controls (1:1, age, sex, and living environment) were evaluated. The patients with CRC (CRC group) and controls were assessed at baseline (before surgical intervention for patients with CRC). Patients with CRC were also evaluated at 1-year follow-up. Significantly more patients with blood group A (54.5% vs. 25.0%) and smokers (50.0% vs. 22.7%) were in the CRC group. The serum values of chitotriosidase and neopterin were higher in CRC patients than in controls, but only neopterin reached the conventional level of statistical significance (p-value = 0.015). The circulating chitotriosidase and neopterin values decreased significantly at 1-year follow-up (p-value < 0.0001). Patients with higher N- and M-stage showed statistically significant higher levels of chitotriosidase and neopterin at baseline and 1-year follow-up (p-values < 0.03). Circulating chitotriosidase levels also showed statistically significant differences regarding baseline and 1-year follow-up on patients with CRC and different differentiation grades (p-values < 0.02). The circulating levels of neopterin significantly decreased at 1-year follow-up, indicating its potential as a prognostic marker. The circulating values of chitotriosidase and neopterin exhibit significant differences in patients with than without recurrences. Our results support further evaluation of chitotriosidase and neopterin as prognostic markers in patients with CRC.

United we thrive: friendship and subsequent physical, behavioural and psychosocial health in older adults (an outcome-wide longitudinal approach).

Three factors converge to underscore the heightened importance of evaluating the potential health/well-being effects of friendships in older adulthood. First, policymakers, scientists, and the public alike are recognizing the importance of social relationships for health/well-being and creating national policies to promote social connection. Second, many populations are rapidly aging throughout the world. Third, we currently face what some call a 'friendship recession'. Although, growing research documents associations between friendship with better health and well-being, friendship can also have a 'dark side' and can potentially promote negative outcomes. To better capture friendship's potential heterogeneous effects, we took an outcome-wide analytic approach. We analysed data from 12,998 participants in the Health and Retirement Study (HRS) - a prospective and nationally representative cohort of U.S. adults aged >50, and, evaluated if increases in friendship strength (between t0; 2006/2008 and t1; 2010/2012) were associated with better health/well-being across 35 outcomes (in t2; 2014/2016). To assess friendship strength, we leveraged all available friendship items in HRS and created a composite 'friendship score' that assessed the following three domains: (1) friendship network size, (2) friendship network contact frequency and (3) friendship network quality. Stronger friendships were associated with better outcomes on some indicators of physical health (e.g. reduced risk of mortality), health behaviours (e.g. increased physical activity) and nearly all psychosocial indicators (e.g. higher positive affect and mastery, as well as lower negative affect and risk of depression). Friendship was also associated with increased likelihood of smoking and heavy drinking (although the latter association with heavy drinking did not reach conventional levels of statistical significance). Our findings indicate that stronger friendships can have a dual impact on health and well-being. While stronger friendships appear to mainly promote a range of health and well-being outcomes, stronger friendships might also promote negative outcomes. Additional research is needed, and any future friendship interventions and policies that aim to enhance outcomes should focus on how to amplify positive outcomes while mitigating harmful ones.

Is the mediating effect of psychosocial stress on the income–health relationship moderated by income inequality?

BackgroundThere now exists a rich body of literature on the relationship between income, income inequality, and health. The discussion about the impact of income and income inequality on health includes psychosocial mechanisms, such as long-term perceptions of inferiority and social positioning, material advantage from income, and the structural conditions that define what people can do with their material resources. AimsThis study investigated the extent to which income's effects on health are mediated by psychosocial stress, and to what extent those effects are moderated by country-level income inequality and economic development. MethodsData were collected from The European Social Survey, round 7. Multilevel moderated mediation analysis was applied to estimate the extent of psychosocial stress mediation of the effects of income on self-rated health. Moderated parameters were estimated over country-level income inequality and economic development. ResultsSignificant full or partial meditation by psychosocial stress was found in all 20 countries studied. Effects moderated by income inequality and GDP per capita showed expected relationships but failed to reach conventional levels of statistical significance. ConclusionsIndividual-level income remains important for explaining the income–health gradient in self-rated health in Europe. The income–health relationship and the extent to which it is mediated by psychosocial stress varies among countries but is not significantly moderated by contextual income or income inequality. Policies should be aimed at allowing a greater proportion of people to live in material comfort and reduced sense of financial precarity, and protecting individuals from harmful consequences of low income.

Young Age on Starting Prostate-specific Antigen Testing Is Associated with a Greater Reduction in Prostate Cancer Mortality: 24-Year Follow-up of the Göteborg Randomized Population-based Prostate Cancer Screening Trial

BackgroundThe risk of death from prostate cancer (PC) depends on age, but the age at which to start prostate-specific antigen (PSA) screening remains uncertain. ObjectiveTo study the relationship between risk reduction for PC mortality and age at first PSA screening. Design, setting, and participantsThe randomized Göteborg-1 trial invited men for biennial PSA screening between the ages of 50 and 70 yr (screening, n = 10 000) or no invitation but exposure to opportunistic PSA testing (control, n = 10 000). InterventionRegular versus opportunistic PSA screening or no PSA. Outcome measurements and statistical analysisWe modeled the nonlinear association between starting age and the absolute risk reduction in PC mortality in three settings: (1) intention-to-screen (randomized arms); (2) historical control (screening group and 1990–1994 registry data); and (3) attendees only (screening attendees and matched controls). We tested whether the effect of screening on PC mortality depends on the age at starting screening by comparing survival models with and without an interaction between trial arm and age (intention-to-screen and attendees only). Results and limitationsYounger age on starting PSA testing was associated with a greater reduction in PC mortality. Starting screening at age 55 yr approximately halved the risk of PC death compared to first PSA at age 60 yr. The test of association between starting age and the effect of screening on PC mortality was slightly greater than the conventional level of statistical significance (p = 0.052) for the entire cohort, and statistically significant among attendees (p = 0.002). This study is limited by the low number of disease-specific deaths for men starting screening before age 55 yr and the difficulty in discriminating between the effect of starting age and screening duration. ConclusionsGiven that prior screening trials included men aged up to 70 yr on starting screening, our results suggest that the effect size reported in prior trials underestimates that of currently recommended programs starting at age 50–55 yr. Patient summaryIn this study from the Göteborg-1 trial, we looked at the effect of prostate-specific antigen (PSA) screening in reducing men’s risk of dying from prostate cancer given the age at which they begin testing. Starting at a younger age reduced the risk of prostate cancer death by a greater amount. We recommend that PSA screening should start no later than at age 55 yr.

Adjuvant chemotherapy in early-stage endometrioid endometrial cancer with >50% myometrial invasion and negative lymph nodes

ObjectiveThe role of adjuvant chemotherapy as an addition or alternative to radiotherapy for early-stage high-risk endometrioid endometrial cancer is controversial. This study aimed to investigate the role of adjuvant chemotherapy...

Urban upbringing and psychiatric disorders in the United States: A racial comparison.

Studies that link urbanicity to mental health are mixed depending on outcome and context. More research is needed to examine whether the urban upbringing effect holds true across racial populations in a large and diverse country like the United States. We analyzed two large datasets that were administered contemporaneously with similar methods: The National Comorbidity Survey-Replication (NCS-R, Whites) and the National Survey of American Life (NSAL, Blacks). We ran multivariable logistic regression models to examine the associations between area of upbringing (urban/large city, other, rural) and six psychiatric disorders, controlling for sex, age, years of education and income-to-poverty ratio (and ethnicity in the NSAL). We performed these analyses in both the NCS-R and the NSAL separately. The majority (58.97%) of the White sample grew up in the 'other' category (i.e. small town, small city, or suburb of a large city), whereas a much larger percentage (39.89%) of the Black sample grew up in a large city. In the White sample, urban upbringing was not associated with any of the psychiatric disorders at a conventional level of statistical significance. In the Black sample, urban upbringing was associated with greater odds of having mood disorder, alcohol use disorder and drug use disorder, but was not significantly associated with anxiety disorders, PTSD, or eating disorders. Urban upbringing was not associated with psychiatric disorders among Whites, but was associated with greater odds of mood disorders, alcohol us disorder and drug use disorder among Blacks. Future research can elucidate how differences in urban upbringing between Whites and Blacks are linked to differences in risk for psychiatric disorders.

Treatment for Post-hemorrhagic Ventricular Dilatation: A Multiple-Treatment Meta-Analysis.

Objective: To perform a systematic review and multiple-treatment meta-analysis for the treatment of premature infants with post-hemorrhagic ventricular dilatation (PHVD), to prevent death or long-term neuro-disability.Design/Method: A systematic review was performed using PubMed, EMBASE, and the Cochrane Library. A free-word search was performed to identify likely relevant literature intervention trials of PHVD in preterm infants. Initially, network mapping was performed followed by performing a Bayesian random-effects model using the Markov chain Monte Carlo method. Areas under the cumulative ranking curve (SUCRA) were calculated as a measure of the probability that each intervention was likely to be the 1st, 2nd, 3rd, etc. best therapy. Primary outcome measure was death or moderate or severe neurodevelopmental outcome at or beyond 12 months of corrected age.Results: Ten different trials were identified, enrolling 700 individuals (449 for the primary outcome). Seven intervention categories were identified, and of the 15 possible pair comparisons, 6 have been studied directly. In the multiple-treatment meta-analysis, no comparison reached conventional levels of statistical significance. Drainage Irrigation and Fibrinolytic Therapy (DRIFT) had the highest probability of being the best treatment for the primary outcome (82.1%), followed by CSF removal (10.8%), conservative management (6.7%), and then diuretic therapy (0.4%).Conclusions: PHVD is a significant cause of death and disability in developed countries, yet few therapeutic options have so far been trialed. While new therapies are urgently needed for these infants, at present, NMA shows that DRIFT appears to be the most likely candidate to improve outcomes after sIVH.

Discrimination and Multimorbidity Among Black Americans: Findings from the National Survey of American Life.

There is a notable lack of research on the risk factors for multimorbidity, which has become more common over recent decades. Black Americans experience discrimination more often than their White counterparts, and also have significantly higher prevalence of multimorbidity. This paper examines the associations between discrimination and multimorbidity among Black Americans. We analyzed data from the National Survey of American Life to calculate the prevalence of two types of discrimination (everyday discrimination, major discriminatory events) and multimorbidity (physical, psychiatric, mixed, any). Using multivariable logistic regression, we examined the associations between discrimination and multimorbidity, adjusting for age, sex, years of education, income-to-poverty ratio, and ethnicity. The everyday discrimination scale was discretized into five categories (none, low, medium, high, very high), but was also treated as a continuous variable. The major discriminatory events were analyzed in separate adjusted models, and as a count of events. When compared with those who did not experience any discrimination, people who experienced everyday discrimination were significantly more likely to report all types of multimorbidity in a dose-response fashion at a conventional level of statistical significance. Most major discriminatory events were associated with greater odds of reporting all types of multimorbidity, as were the counts of major discriminatory events, in a dose-response fashion. We found strong evidence to suggest that discrimination was associated with greater odds of reporting multimorbidity. Future studies can expand on these findings using longitudinal data to capture the relations between discrimination and health over time, or by testing preventive interventions that allay the damaging health effects of discrimination.

Peritoneal Dialysis–Related Infection Rates and Outcomes: Results From the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS)

Peritoneal dialysis (PD)-related peritonitis carries high morbidity for PD patients. Understanding the characteristics and risk factors for peritonitis can guide regional development of prevention strategies. We describe peritonitis rates and the associations of selected facility practices with peritonitis risk among countries participating in the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS). Observational prospective cohort study. 7,051 adult PD patients in 209 facilities across 7 countries (Australia, New Zealand, Canada, Japan, Thailand, United Kingdom, United States). Facility characteristics (census count, facility age, nurse to patient ratio) and selected facility practices (use of automated PD, use of icodextrin or biocompatible PD solutions, antibiotic prophylaxis strategies, duration of PD training). Peritonitis rate (by country, overall and variation across facilities), microbiology patterns. Poisson rate estimation, proportional rate models adjusted for selected patient case-mix variables. 2,272 peritonitis episodes were identified in 7,051 patients (crude rate, 0.28 episodes/patient-year). Facility peritonitis rates were variable within each country and exceeded 0.50/patient-year in 10% of facilities. Overall peritonitis rates, in episodes per patient-year, were 0.40 (95% CI, 0.36-0.46) in Thailand, 0.38 (95% CI, 0.32-0.46) in the United Kingdom, 0.35 (95% CI, 0.30-0.40) in Australia/New Zealand, 0.29 (95% CI, 0.26-0.32) in Canada, 0.27 (95% CI, 0.25-0.30) in Japan, and 0.26 (95% CI, 0.24-0.27) in the United States. The microbiology of peritonitis was similar across countries, except in Thailand, where Gram-negative infections and culture-negative peritonitis were more common. Facility size was positively associated with risk for peritonitis in Japan (rate ratio [RR] per 10 patients, 1.07; 95% CI, 1.04-1.09). Lower peritonitis risk was observed in facilities that had higher automated PD use (RR per 10 percentage points greater, 0.95; 95% CI, 0.91-1.00), facilities that used antibiotics at catheter insertion (RR, 0.83; 95% CI, 0.69-0.99), and facilities with PD training duration of 6 or more (vs<6) days (RR, 0.81; 95% CI, 0.68-0.96). Lower peritonitis risk was seen in facilities that used topical exit-site mupirocin or aminoglycoside ointment, but this association did not achieve conventional levels of statistical significance (RR, 0.79; 95% CI, 0.62-1.01). Sampling variation, selection bias (rate estimates), and residual confounding (associations). Important international differences exist in the risk for peritonitis that may result from varied and potentially modifiable treatment practices. These findings may inform future guidelines in potentially setting lower maximally acceptable peritonitis rates.

In Organ-confined Prostate Cancer, Tumor Quantitation Not Found to Aid in Prediction of Biochemical Recurrence.

In the eighth edition AJCC staging, all organ-confined disease is assigned pathologic stage T2, without subclassification. We investigated whether total tumor volume (TTV) and/or maximum tumor diameter (MTD) of the index lesion are useful in improving prediction of biochemical recurrence (BCR) in pT2 patients. We identified 1657 patients with digital tumor maps and quantification of TTV/MTD who had pT2 disease on radical prostatectomy (RP). Multivariable Cox regression models were used to assess whether TTV and/or MTD are independent predictors of BCR when adjusting for a base model incorporating age, preoperative prostate-specific antigen, RP grade group, and surgical margin status. If either tumor quantification added significantly, we calculated and reported the c-index. Ninety-five patients experienced BCR after RP; median follow-up for patients without BCR was 5.7 years. The c-index was 0.737 for the base model. Although there was some evidence of an association between TTV and BCR (P=0.088), this did not meet conventional levels of statistical significance and only provided a limited increase in discrimination (0.743; c-index improvement: 0.006). MTD was not associated with BCR (P>0.9). In analyses excluding patients with grade group 1 on biopsy who would be less likely to undergo RP in contemporary practice (622 patients; 59 with BCR), TTV/MTD was not a statistically significant predictor (P=0.4 and 0.8, respectively). Without evidence that tumor quantitation, in the form of either TTV or MTD of the index lesion, is useful for the prediction of BCR in pT2 prostate cancer, we cannot recommend its routine reporting.

Longitudinal associations between number of cigarettes per day and depressive symptoms in adult smokers with type 2 diabetes: A path analysis approach

ObjectiveThree theoretical models describe the direction of the association between depressive symptoms and cigarettes per day (CPD) in smokers: 1) CPD predicts subsequent depressive symptoms, 2) depressive symptoms predict CPD, and 3) there is a bidirectional relation between CPD and depressive symptoms. The objective of the study was to compare the fit of these three theoretical models to data from a community-based sample of adults with type 2 diabetes (T2D) who smoke cigarettes. MethodsData were from adults with T2D who participated in the Evaluation of Diabetes Treatment Study. At baseline, 296 participants reported being a current smoker and were included in the analyses. Measures of CPD and depressive symptoms were collected annually over four years. Path models corresponding to the three directionality hypotheses were estimated. Model fit was compared, and the best fitting model was selected on the basis of Akaike's Information Criterion (AIC). ResultsThe path model depicting a unidirectional association from CPD to subsequent depressive symptoms had the lowest AIC value (7110.94) and was thus identified as the best fitting model. Although some paths within the model did not meet conventional levels of statistical significance, in general, more CPD predicted higher levels of depressive symptoms at subsequent follow-up points. ConclusionAmongst smokers with T2D, a primary smoking model, in which smoking precedes depressive symptoms, may best explain the longitudinal association between CPD and depressive symptoms. These findings further justify the need for early smoking cessation in diabetes care.

Home visits for uncontrolled asthma among low-income adults with patient portal access

Asthma disproportionately affects low-income and minority adults. In an era of electronic records and Internet-based digital devices, it is unknown whether portals for patient-provider communication can improve asthma outcomes. We sought to estimate the effect on asthma outcomes of an intervention using home visits (HVs) by community health workers (CHWs) plus training in patient portals compared with usual care and portal training only. Three hundred one predominantly African American and Hispanic/Latino adults with uncontrolled asthma were recruited from primary care and asthma specialty practices serving low-income urban neighborhoods, directed to Internet access, and given portal training. Half were randomized to HVs over 6months by CHWs to facilitate competency in portal use and promote care coordination. One hundred seventy (56%) patients used the portal independently. Rates of portal activity did not differ between randomized groups. Asthma control and asthma-related quality of life improved in both groups over 1year. Differences in improvements over time were greater for the HV group for all outcomes but reached conventional levels of statistical significance only for the yearly hospitalization rate (-0.53; 95% CI, -1.08 to -0.024). Poor neighborhoods and living conditions plus limited Internet access were barriers for patients to complete the protocol and for CHWs to make HVs. For low-income adults with uncontrolled asthma, portal access and CHWs produced small incremental benefits. HVs with emphasis on self-management education might be necessary to facilitate patient-clinician communication and to improve asthma outcomes.

Bill Gross' Alpha: The King Versus the Oracle

We set out to investigate whether ''Bond King Bill Gross demonstrated alpha (excess average return after adjusting for market exposures) over his career, in the spirit of earlier papers asking the same question of ''Oracle of Omaha, Warren Buffett. The journey turned out to be more interesting than the destination. We do find, contrary to previous research, that Gross demonstrated alpha at conventional levels of statistical significance. But we also find that result depends less on the historical record than on whether we take the perspective of academics interested in market efficiency, investors picking a fund or someone (say a potential employer) asking whether a manager has skill or is throwing darts to pick positions. These are often thought to be overlapping or even identical questions. That's not completely unreasonable in equity markets, but in fixed income these are distinct. We also find quantitative differences, mainly that fixed-income securities have much higher correlations with each other than equities, make alpha 4.5 times as hard to measure for Gross than Buffett. We don't think our results will have much practical effect on attitudes toward Gross as an investor, but we hope they will advance understanding of what alpha means and appropriate ways to estimate it.

Disordered sleep and myopia among adolescents: a propensity score matching analysis

ABSTRACTPurpose: Observational studies have suggested a possible relationship between disordered sleep and myopia, but the association may be subject to selection biases. We aimed to minimize selection biases and assess the association by applying a propensity score matching (PSM) approach.Methods: The study was designed as a school-based cross-sectional study on a Chinese cohort aged 13–14 years in rural areas of China. The Chinese version of the Children’s Sleep Habits Questionnaire was used for the measurement of sleep quality and a score of 41 or more was used to define the presence of disordered sleep. Each participant’s refractive status was measured after cycloplegia using an autorefractor and myopia was defined as spherical equivalent <−0.50 D. The propensity scores for disordered sleep were formulated using nine potential confounders. We matched the propensity scores for subjects with and without disordered sleep within a caliper of 0.01 of logit function of propensity scores.Results: In this study, 474 pairs (1 subject with vs. 1 subject without disordered sleep) were successfully matched based on propensity scores. The odds ratio (OR) of myopia for disordered sleep before PSM reached conventional levels of statistical significance (OR: 1.43 95% confidence interval [CI] 1.05, 2.58, p = 0.01). After matching, the magnitude of association was reduced and the OR of myopia was not significant (OR: 1.54 95% CI 0.90, 2.57, p = 0.46).Conclusions: At current stage, there are insufficient evidence indicating that disordered sleep could affect the development of myopia in adolescents.

Glomerular filtration rate: A prognostic marker in atrial fibrillation-A subanalysis of the AntiThrombotic Agents Atrial Fibrillation.

An increased cardiovascular mortality and morbidity has been widely reported in patients with atrial fibrillation (AF). In this study, a subanalysis of the AntiThrombotic Agents Atrial Fibrillation (ATA-AF) is performed with the aim to evaluate estimated glomerular filtration rate (eGFR) as an independent prognostic marker of cardiovascular mortality and morbidity in patients with AF. The ATA-AF study enrolled 7148 patients with AF, in 360 Italian centers. The eGFR was calculated from data reported in patient notes or hospital database. This post-hoc analysis included 1097 AF patients with eGFR data available and 1-year clinical follow-up. The endpoint was assessed as cardiovascular mortality and/or hospital admission for cardiovascular causes at follow-up. Patients were also divided in two groups according to the eGFR (<60 and ≥60 mL/min/1.73 m2 ). The Kaplan-Meyer curve for the mentioned endpoint showed a higher endpoint incidence in the group of patient with eGFR below 60 mL/min/1.73 m2 (P < 0.001). Using multivariate analysis (Cox regression), a trend toward a higher rate of occurrence of the primary endpoint was observed for eGFR below 60 mL/min/1.73 m2 without reaching the conventional level of statistical significance (hazard ratio [HR] 1.40; 95% confidence interval [CI] 0.99-1.99; P = 0.0572). When eGFR was included in the analysis as continuous variable a significant correlation was observed with the combined endpoint at the Cox regression (HR 0.99, 95% CI 0.98-0.99, P = 0.04). The result of this post-hoc analysis indicates that an impaired eGFR is independently associated with worse prognosis among patients with AF.