The robust variance estimator for two-stage models

This article discusses estimates of variance for two-stage models. We present the sandwich estimate of variance as an alternative to the Murphy-Topel estimate. The sandwich estimator has a simple formula that is similar to the formula for the Murphy ÐTopel estimator,and the two estimators are asymptotically equal when the assumed model distributions are true. The advantages of the sandwich estimate of variance are that it may be calculated for the complete parameter vector, and that it requires estimating equations instead of fully specified log likelihoods. Copyright 2002 by Stata Corporation.robust variance estimator,Murphy-Topel estimator,two-stage estimation,estimating equation

Measurement error, GLMs, and notational conventions

This paper introduces additive measurement error in a generalized linear-model context. We discuss the types of measurement error along with their effects on fitted models. In addition, we present the notational conventions to be used in this and the accompanying papers. Copyright 2003 by StataCorp LP.generalized linear models, transportability, measurement error

Variance estimation for the instrumental variables approach to measurement error in generalized linear models

This paper derives and gives explicit formulas for a derived sandwich variance estimate. This variance estimate is appropriate for generalized linear additive measurement error models fitted using instrumental variables. We also generalize the known results for linear regression. As such, this article explains the theoretical justification for the sandwich estimate of variance utilized in the software for measurement error developed under the Small Business Innovation Research Grant (SBIR) by StataCorp. The results admit estimation of variance matrices for measurement error models where there is an instrument for the unknown covariate. Copyright 2003 by StataCorp LP.sandwich estimate of variance, measurement error, White's estimator, robust variance, generalized linear models, instrumental variables

Studies In The Hippocastanaceae Ii. Inflorescence Structure And Distribution Of Perfect Flowers

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142159/1/ajb210511.pd

The Association Between Phosphodiesterase-5 Inhibitors and Colorectal Cancer in a National Cohort of Patients

INTRODUCTION: To examine the association between phosphodiesterase-5 (PDE-5) inhibitor use and incidence of colorectal cancer among patients with erectile dysfunction treated in the Veterans Affairs (VA) Healthcare System. METHODS: A retrospective cohort study using the Veterans Affairs Informatics and Computing Infrastructure was conducted, with data spanning January 2001-December 2016. Patients were followed up from index until (i) the first diagnosis of colorectal cancer, (ii) death, or (iii) the end of study period. Statistical analyses evaluated demographics and baseline characteristics between cohorts (PDE-5 exposed or not) and the effect of additional dosages of each specific PDE-5 inhibitor using adjusted multivariate Cox proportional hazards models. RESULTS: A total of 221,538 patients met the study inclusion criteria, 192,691 patients in the PDE-5 cohort and 29,227 patients in the never use PDE-5 cohort. The multivariate Cox proportional hazards model results revealed that the those who had any exposure to a PDE-5 inhibitor have an 18% lower hazard of colorectal cancer (adjusted hazard ratio [HR] = 0.816, 95% confidence interval [CI] = 0.754-0.882). For each additional 100-mg dosage of sildenafil and 10-mg dosage of tadalafil, the hazard of colorectal cancer is reduced by 2.4% (adjusted HR = 0.976, 95% CI = 0.973-0.979) and 1.7% (adjusted HR = 0.983, 95% CI = 0.972-0.996), respectively. DISCUSSION: PDE-5 inhibitor usage in patients with erectile dysfunction is associated with a lower hazard of colorectal cancer compared with patients not exposed to PDE-5 inhibitors

Odds of Acute Kidney Injury in Patients Receiving Dipeptidyl Peptidase 4 Inhibitors: A National Cohort Study Within the Department of Veterans Affairs

Preclinical and clinical data of dipeptidyl peptidase 4 (DPP‐4) inhibitors have demonstrated discordant data regarding acute kidney injury (AKI). Therefore, we aimed to evaluate the association between DPP‐4 use and AKI. This cohort study utilized data from the Department of Veterans Affairs evaluating patients diagnosed with type 2 (T2) diabetes with a DPP‐4 inhibitor and compared with nondiabetic and diabetic patients. The primary end point is the development of AKI, and statistical analyses were performed to examine the association. DPP‐4 use is associated with a lower odds of AKI compared with diabetics (adjusted odds ratio (OR) = 0.39; 95% confidence interval (CI) = 0.32–0.48) and nondiabetics (OR = 0.64; 95% CI = 0.52–0.79). DPP‐4 use in patients with T2 diabetes mellitus is associated with lower odds of AKI within 120 days compared with nondiabetic and diabetic controls when adjusting for study covariates

Antenatal Care Satisfaction in a Developing Country: A Cross-Sectional Study From Nigeria

Background Utilization of Antenatal Care (ANC) is very low in Nigeria. Self-reported patient satisfaction may be useful to identify provider- and facility-specific factors that can be improved to increase ANC satisfaction and utilization. Methods Exit interview data collected from ANC users and facility assessment survey data from 534 systematically selected facilities in four northern Nigerian states were used. Associations between patient satisfaction (satisfied, not-satisfied) and patient ratings of the provider’s interactions, care processes, out-of-pocket costs, and quality of facility infrastructure were studied. Results Of 1336 mothers, 90% were satisfied with ANC. Patient satisfaction was positively associated with responsive service (prompt, unrushed service, convenient clinic hours and privacy during consultation, AOR 2.42, 95% CI 2.05–2.87), treatment-facilitation (medical care-related provider communication and ease of receiving medicines, AOR 2.03, 95% CI 1.46–2.80), equipment availability (AOR 1.10, 95% CI 1.01–1.21), staff empathy (AOR 1.82, 95% CI 1.03–3.23), non-discriminatory treatment regardless of patient’s socioeconomic status (AOR: 1.87, 95% CI 1.09–3.22), provider assurance (courtesy and patient’s confidence in provider’s competence, AOR 1.48, 95% CI 1.26–1.75), and number of clinical examinations received (AOR 1.28, 95% CI 1.10–1.50). ANC satisfaction was negatively impacted by out-of-pocket payment for care (vs. free care, AOR 0.44, 95% CI 0.23–0.82). Conclusions ANC satisfaction in Nigeria may be enhanced by improving responsiveness to clients, clinical care quality, ensuring equipment availability, optimizing easy access to medicines, and expanding free ANC services

Exploring the Impact of Efficacy Messages on Cessation-Related Outcomes Using Ecological Momentary Assessment

Introduction:Observational studies indicate that cigarette package inserts with efficacy messages about the benefits of quitting (i.e. response efficacy) and recommendations for successful cessation increase smokers’ self-efficacy to quit and promote sustained cessation. However, the effects of inserts with such efficacy messages have not been studied using experimental designs. This study used ecological momentary assessment (EMA) to assess smokers’ responses to efficacy inserts.Material and Methods:In a randomized case-crossover study among smokers from the United States (n=23), participants received a one-week supply of cigarettes with efficacy inserts and a one-week supply without any inserts, and were randomized to use the packs with inserts on either the first or second week of the study. For 14 consecutive days, participants used a smartphone to answer brief surveys on cessation-related variables during smoking sessions and at the beginning of each day. Multilevel mixed-effects linear and logistic regression models compared responses during the insert period to those of the non-insert period.Results:The insert period was associated with greater desire to quit (b=0.21, p=0.012), motivation to quit (b=0.18, p=0.001), self-efficacy to cut down (b=0.26, p\u3c0.001) and to quit (b=0.28, p\u3c0.000), and response efficacy/ perceived benefits of quitting (b=0.13, p=0.012). Insert exposure was not significantly associated with forgoing cigarettes (OR=1.9, p=0.2).Conclusions:Results from this EMA study suggest that inserts with efficacy messages may promote determinants of smoking cessation. This is consistent with observational research in Canada, which is the only country to use inserts with efficacy messages as well as pictorial warnings about smoking risks on the outside of packs. Future studies should assess the extent to which efficacy inserts can not only be used to communicate health information to smokers but also work in synergy with pictorial warnings

Infantile spasms (West syndrome): update and resources for pediatricians and providers to share with parents

Background Infantile spasms (IS; West syndrome) is a severe form of encephalopathy that typically affects infants younger than 2 years old. Pediatricians, pediatric neurologists, and other pediatric health care providers are all potentially key early contacts for families who have an infant with IS. The objective of this article is to assist pediatric health care providers in the detection of the disease and in the counseling and guidance of families who have an infant with IS. Methods Treatment guidelines, consensus reports, and original research studies are reviewed to provide an update regarding the diagnosis and treatment of infants with IS. Web sites were searched for educational and supportive resource content relevant to providers and families of patients with IS. Results Early detection of IS and pediatrician referral to a pediatric neurologist for further evaluation and initiation of treatment may improve prognosis. Family education and the establishment of a multidisciplinary continuum of care are important components of care for the majority of patients with IS. The focus of the continuum of care varies across diagnosis, initiation of treatment, and short- and long-term needs. Several on-line educational and supportive resources for families and caregivers of patients with IS were identified. Conclusions Given the possibility of poor developmental outcomes in IS, including the emergence of other seizure disorders and cognitive and developmental problems, early recognition, referral, and treatment of IS are important for optimal patient outcomes. Dissemination of and access to educational and supportive resources for families and caregivers across the lifespan of the child with IS is an urgent need. Pediatric health care providers are well positioned to address these needs