Purushottam W. Laud

Predictive Factors and Outcomes in Endoscopic Sinus Surgery for Chronic Rhinosinusitis

Purpose: To assess objective and quality of life (QOL) outcomes before and after endoscopic sinus surgery (ESS) in patients with chronic rhinosinusitis (CRS) and to determine preoperative factors that predict surgical outcome in these patients.

Bayesian Nonparametric Inference for Random Distributions and Related Functions

In recent years, Bayesian nonparametric inference, both theoretical and computational, has witnessed considerable advances. However, these advances have not received a full critical and comparative analysis of their scope, impact and limitations in statistical modelling; many aspects of the theory and methods remain a mystery to practitioners and many open questions remain. In this paper, we discuss and illustrate the rich modelling and analytic possibilities that are available to the statistician within the Bayesian nonparametric and/or semiparametric framework.

On Bayesian Analysis of Generalized Linear Models Using Jeffreys's Prior

Abstract Generalized linear models (GLMs) have proved suitable for modeling various kinds of data consisting of exponential family response variables with covariates. Bayesian analysis of such data requires specification of a prior for the regression parameters in the model used. Uniform priors are very commonly used as conventional noninformative priors. We show, however, that uniform priors for GLMs can lead to improper posterior distributions thus making them undesirable. Alternative reference priors may be constructed from Jeffreyss rule. In this article, we give two theorems that support the use of Jeffreyss priors for GLMs with intrinsically fixed or known scale parameters. These theorems provide (i) sufficient and (ii) necessary and sufficient conditions for the propriety of the (i) posterior and (ii) prior distributions as well as for the existence of moments. Implications of these theorems for some commonly used GLMs are discussed. Finally, an illustrative example is given for the binomial ...

Obesity and Risk for Death Due to Motor Vehicle Crashes

OBJECTIVES We examined the role of body mass index (BMI) and other factors in driver deaths within 30 days after motor vehicle crashes. METHODS We collected data for 22 107 drivers aged 16 years and older who were involved in motor vehicle crashes from the Crashworthiness Data System of the National Automotive Sampling System (1997-2001). We used logistic regression and adjusted for confounding factors to analyze associations between BMI and driver fatality and the associations between BMI and gender, age, seatbelt use, type of collision, airbag deployment, and change in velocity during a crash. RESULTS The fatality rate was 0.87% (95% confidence interval [CI]=0.50, 1.24) among men and 0.43% (95% CI=0.31, 0.56) among women involved as drivers in motor vehicle crashes. Risk for death increased significantly at both ends of the BMI continuum among men but not among women (P<.05). The association between BMI and male fatality increased significantly with a change in velocity and was modified by the type of collision, but it did not differ by age, seatbelt use, or airbag deployment. CONCLUSIONS The increased risk for death due to motor vehicle crashes among obese men may have important implications for traffic safety and motor vehicle design.

A Predictive Approach to the Analysis of Designed Experiments

Abstract Viewing the analysis of designed experiments as a model selection problem, we introduce the use of a predictive Bayesian criterion in this context based on the predictive density of a replicate experiment (PDRE). A calibration of the criterion is provided to assist in the model choice. The relationships of the proposed criterion to other prevalent criteria, such as AIC, BIC, and Mallowss C p , are given. An information theoretic criterion based on the PDREs of two competing models is also introduced and compared with the usual F statistic for two nested models. Examples are given to illustrate the proposed methodology.

Patient satisfaction with physician-patient communication during telemedicine.

The quality of physician-patient communication is a critical factor in treatment outcomes and patient satisfaction with care. To date, few studies have specifically conducted an in-depth evaluation of the effect of telemedicine (TM) on physician-patient communication in a medical setting. Our objective was to determine whether physical separation and technology used during TM have a negative effect on physician-patient communication. In this noninferiority randomized clinical trial, patients were randomized to receive a single consultation with one of 9 physicians, either in person (IP) or via TM. Patients (n = 221) were recruited from pulmonary, endocrine, and rheumatology clinics at a Midwestern Veterans Administration hospital. Physician-patient communication was measured using a validated self-report questionnaire consisting of 33 items measuring satisfaction with visit convenience and physicians patient-centered communication, clinical competence, and interpersonal skills. Satisfaction for physicians patient-centered communication was similar for both consultation types (TM = 3.76 versus IP = 3.61), and noninferiority of TM was confirmed (noninferiority t-test p = 0.002). Patient satisfaction with physicians clinical competence (TM = 4.63 versus IP = 4.52) and physicians interpersonal skills (TM = 4.79 versus IP = 4.74) were similar, and noninferiority of TM was confirmed (noninferiority t-test p = 0.006 and p = 0.04, respectively). Patients reported greater satisfaction with convenience for TM as compared to IP consultations (TM = 4.41 versus IP = 2.37, noninferiority t-test p < 0.001). Patients were equally satisfied with physicians ability to develop rapport, use shared decision making, and promote patient-centered communication during TM and IP consultations. Our data suggest that, despite physical separation, physician-patient communication during TM is not inferior to communication during IP consultations.

Apoptosis of CD4+CD25high T Cells in Type 1 Diabetes May Be Partially Mediated by IL-2 Deprivation

Background Type 1 diabetes (T1D) is a T-cell mediated autoimmune disease targeting the insulin-producing pancreatic β cells. Naturally occurring FOXP3+CD4+CD25high regulatory T cells (Tregs) play an important role in dominant tolerance, suppressing autoreactive CD4+ effector T cell activity. Previously, in both recent-onset T1D patients and β cell antibody-positive at-risk individuals, we observed increased apoptosis and decreased function of polyclonal Tregs in the periphery. Our objective here was to elucidate the genes and signaling pathways triggering apoptosis in Tregs from T1D subjects. Principal Findings Gene expression profiles of unstimulated Tregs from recent-onset T1D (n = 12) and healthy control subjects (n = 15) were generated. Statistical analysis was performed using a Bayesian approach that is highly efficient in determining differentially expressed genes with low number of replicate samples in each of the two phenotypic groups. Microarray analysis showed that several cytokine/chemokine receptor genes, HLA genes, GIMAP family genes and cell adhesion genes were downregulated in Tregs from T1D subjects, relative to control subjects. Several downstream target genes of the AKT and p53 pathways were also upregulated in T1D subjects, relative to controls. Further, expression signatures and increased apoptosis in Tregs from T1D subjects partially mirrored the response of healthy Tregs under conditions of IL-2 deprivation. CD4+ effector T-cells from T1D subjects showed a marked reduction in IL-2 secretion. This could indicate that prior to and during the onset of disease, Tregs in T1D may be caught up in a relatively deficient cytokine milieu. Conclusions In summary, expression signatures in Tregs from T1D subjects reflect a cellular response that leads to increased sensitivity to apoptosis, partially due to cytokine deprivation. Further characterization of these signaling cascades should enable the detection of genes that can be targeted for restoring Treg function in subjects predisposed to T1D.

Relationship Between Number of Breast Cancer Operations Performed and 5-Year Survival After Treatment for Early-Stage Breast Cancer

OBJECTIVES We examined the association between number of breast cancer operations performed in a hospital (hospital volume) and all-cause and breast cancer-specific mortality using a national database and statistical methods appropriate for clustering and reducing confounding. METHODS In a retrospective cohort study, we linked Surveillance, Epidemiology, and End Results tumor registry data with Medicare claims data. The cohort included 11225 Medicare patients who had undergone surgery for early-stage breast cancer from 1994 to 1996 in 457 different hospitals. Primary outcomes were all-cause and breast cancer-specific survival rates at a mean follow-up time of 62.5 months. RESULTS In comparison with treatment in a low-volume hospital, treatment in a high-volume hospital was associated with hazard ratios of 0.83 (95% confidence interval [CI]=0.75, 0.92) for all-cause mortality and 0.80 (CI=0.66, 0.97) for breast cancer-specific mortality. CONCLUSIONS An association between the volume of breast cancer operations performed in a hospital and 5-year survival rates was observed for both all-cause and breast cancer-specific mortality. Further work investigating the aspects of hospital volume that contribute to increased survival is warranted.

A framework for health numeracy: how patients use quantitative skills in health care.

Our objective of this study is to develop a conceptual framework for the construct of health numeracy based on patient perceptions, using a cross-sectional, qualitative design. Interested participants (n = 59) meeting eligibility criteria (age 40–74, English speaking) were assigned to one of six focus groups stratified by gender and educational level (low, medium, high). Fifty-three percent were male, and 47% were female. Sixty-one percent were white non-Hispanic, and 39% were of minority race or ethnicity. Participants were randomly selected from three primary care sites associated with an academic medical center. Focus group discussions were held in May 2004 and focused on how numbers are used in the health care setting. Data were presented from clinical trials to further explore how quantitative information is used in health communication and decision making. Focus groups were audio and videotaped; verbatim transcripts were prepared and analyzed. A framework of health numeracy was developed to reflect the themes that emerged. Three broad conceptual domains for health numeracy were identified: primary numeric skills, applied health numeracy, and interpretive health numeracy. Across domains, results suggested that numeracy contains an emotional component, with both positive and negative affect reflected in patient numeracy statements. We conclude that health numeracy is a multifaceted construct that includes applied and interpretive components and is influenced by patient affect.

BMI and Risk of Serious Upper Body Injury Following Motor Vehicle Crashes: Concordance of Real-World and Computer-Simulated Observations

Shankuan Zhu and colleagues use computer crash simulations, as well as real-world data, to evaluate whether driver obesity is associated with greater risk of body injury in motor vehicle crashes.