scholarly journals Gamma models for estimating the odds ratio for a skewed biomarker measured in pools and subject to errors

Biostatistics ◽  
2019 ◽  
Author(s):  
Dane R Van Domelen ◽  
Emily M Mitchell ◽  
Neil J Perkins ◽  
Enrique F Schisterman ◽  
Amita K Manatunga ◽  
...  

SUMMARYMeasuring a biomarker in pooled samples from multiple cases or controls can lead to cost-effective estimation of a covariate-adjusted odds ratio, particularly for expensive assays. But pooled measurements may be affected by assay-related measurement error (ME) and/or pooling-related processing error (PE), which can induce bias if ignored. Building on recently developed methods for a normal biomarker subject to additive errors, we present two related estimators for a right-skewed biomarker subject to multiplicative errors: one based on logistic regression and the other based on a Gamma discriminant function model. Applied to a reproductive health dataset with a right-skewed cytokine measured in pools of size 1 and 2, both methods suggest no association with spontaneous abortion. The fitted models indicate little ME but fairly severe PE, the latter of which is much too large to ignore. Simulations mimicking these data with a non-unity odds ratio confirm validity of the estimators and illustrate how PE can detract from pooling-related gains in statistical efficiency. These methods address a key issue associated with the homogeneous pools study design and should facilitate valid odds ratio estimation at a lower cost in a wide range of scenarios.

2021 ◽  
pp. 1-6
Author(s):  
Maria C. Magnus ◽  
Alexandra Havdahl ◽  
Nils-Halvdan Morken ◽  
Knut-Arne Wensaas ◽  
Allen J. Wilcox ◽  
...  

Background Some psychiatric disorders have been associated with increased risk of miscarriage. However, there is a lack of studies considering a broader spectrum of psychiatric disorders to clarify the role of common as opposed to independent mechanisms. Aims To examine the risk of miscarriage among women diagnosed with psychiatric conditions. Method We studied registered pregnancies in Norway between 2010 and 2016 (n = 593 009). The birth registry captures pregnancies ending in gestational week 12 or later, and the patient and general practitioner databases were used to identify miscarriages and induced abortions before 12 gestational weeks. Odds ratios of miscarriage according to 12 psychiatric diagnoses were calculated by logistic regression. Miscarriage risk was increased among women with bipolar disorders (adjusted odds ratio 1.35, 95% CI 1.26–1.44), personality disorders (adjusted odds ratio 1.32, 95% CI 1.12–1.55), attention-deficit hyperactivity disorder (adjusted odds ratio 1.27, 95% CI 1.21–1.33), conduct disorders (1.21, 95% CI 1.01, 1.46), anxiety disorders (adjusted odds ratio 1.25, 95% CI 1.23–1.28), depressive disorders (adjusted odds ratio 1.25, 95% CI 1.23–1.27), somatoform disorders (adjusted odds ratio 1.18, 95% CI 1.07–1.31) and eating disorders (adjusted odds ratio 1.14, 95% CI 1.08–1.22). The miscarriage risk was further increased among women with more than one psychiatric diagnosis. Our findings were robust to adjustment for other psychiatric diagnoses, chronic somatic disorders and substance use disorders. After mutual adjustment for co-occurring psychiatric disorders, we also observed a modest increased risk among women with schizophrenia spectrum disorders (adjusted odds ratio 1.22, 95% CI 1.03–1.44). Conclusions A wide range of psychiatric disorders were associated with increased risk of miscarriage. The heightened risk of miscarriage among women diagnosed with psychiatric disorders highlights the need for awareness and surveillance of this risk group in antenatal care.


2020 ◽  
pp. 1192-1198
Author(s):  
M.S. Mohammad ◽  
Tibebe Tesfaye ◽  
Kim Ki-Seong

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.


2019 ◽  
Author(s):  
Jenevieve Opoku ◽  
Rupali K Doshi ◽  
Amanda D Castel ◽  
Ian Sorensen ◽  
Michael Horberg ◽  
...  

BACKGROUND HIV cohort studies have been used to assess health outcomes and inform the care and treatment of people living with HIV disease. However, there may be similarities and differences between cohort participants and the general population from which they are drawn. OBJECTIVE The objective of this analysis was to compare people living with HIV who have and have not been enrolled in the DC Cohort study and assess whether participants are a representative citywide sample of people living with HIV in the District of Columbia (DC). METHODS Data from the DC Health (DCDOH) HIV surveillance system and the DC Cohort study were matched to identify people living with HIV who were DC residents and had consented for the study by the end of 2016. Analysis was performed to identify differences between DC Cohort and noncohort participants by demographics and comorbid conditions. HIV disease stage, receipt of care, and viral suppression were evaluated. Adjusted logistic regression assessed correlates of health outcomes between the two groups. RESULTS There were 12,964 known people living with HIV in DC at the end of 2016, of which 40.1% were DC Cohort participants. Compared with nonparticipants, participants were less likely to be male (68.0% vs 74.9%, <i>P</i>&lt;.001) but more likely to be black (82.3% vs 69.5%, <i>P</i>&lt;.001) and have a heterosexual contact HIV transmission risk (30.3% vs 25.9%, <i>P</i>&lt;.001). DC Cohort participants were also more likely to have ever been diagnosed with stage 3 HIV disease (59.6% vs 47.0%, <i>P</i>&lt;.001), have a CD4 &lt;200 cells/µL in 2017 (6.2% vs 4.6%, <i>P</i>&lt;.001), be retained in any HIV care in 2017 (72.9% vs 59.4%, <i>P</i>&lt;.001), and be virally suppressed in 2017. After adjusting for demographics, DC Cohort participants were significantly more likely to have received care in 2017 (adjusted odds ratio 1.8, 95% CI 1.70-2.00) and to have ever been virally suppressed (adjusted odds ratio 1.3, 95% CI 1.20-1.40). CONCLUSIONS These data have important implications when assessing the representativeness of patients enrolled in clinic-based cohorts compared with the DC-area general HIV population. As participants continue to enroll in the DC Cohort study, ongoing assessment of representativeness will be required.


Author(s):  
Allan Matthews ◽  
Adrian Leyland

Over the past twenty years or so, there have been major steps forward both in the understanding of tribological mechanisms and in the development of new coating and treatment techniques to better “engineer” surfaces to achieve reductions in wear and friction. Particularly in the coatings tribology field, improved techniques and theories which enable us to study and understand the mechanisms occurring at the “nano”, “micro” and “macro” scale have allowed considerable progress to be made in (for example) understanding contact mechanisms and the influence of “third bodies” [1–5]. Over the same period, we have seen the emergence of the discipline which we now call “Surface Engineering”, by which, ideally, a bulk material (the ‘substrate’) and a coating are combined in a way that provides a cost-effective performance enhancement of which neither would be capable without the presence of the other. It is probably fair to say that the emergence and recognition of Surface Engineering as a field in its own right has been driven largely by the availability of “plasma”-based coating and treatment processes, which can provide surface properties which were previously unachievable. In particular, plasma-assisted (PA) physical vapour deposition (PVD) techniques, allowing wear-resistant ceramic thin films such as titanium nitride (TiN) to be deposited on a wide range of industrial tooling, gave a step-change in industrial productivity and manufactured product quality, and caught the attention of engineers due to the remarkable cost savings and performance improvements obtained. Subsequently, so-called 2nd- and 3rd-generation ceramic coatings (with multilayered or nanocomposite structures) have recently been developed [6–9], to further extend tool performance — the objective typically being to increase coating hardness further, or extend hardness capabilities to higher temperatures.


Author(s):  
Qiao Qin ◽  
Fangfang Fan ◽  
Jia Jia ◽  
Yan Zhang ◽  
Bo Zheng

Abstract Purpose An increase in arterial stiffness is associated with rapid renal function decline (RFD) in patients with chronic kidney disease (CKD). The aim of this study was to investigate whether the radial augmentation index (rAI), a surrogate marker of arterial stiffness, affects RFD in individuals without CKD. Methods A total of 3165 Chinese participants from an atherosclerosis cohort with estimated glomerular filtration rates (eGFR) of ≥ 60 mL/min/1.73 m2 were included in this study. The baseline rAI normalized to a heart rate of 75 beats/min (rAIp75) was obtained using an arterial applanation tonometry probe. The eGFRs at both baseline and follow-up were calculated using the equation derived from the Chronic Kidney Disease Epidemiology Collaboration. The association of the rAIp75 with RFD (defined as a drop in the eGFR category accompanied by a ≥ 25% drop in eGFR from baseline or a sustained decline in eGFR of > 5 mL/min/1.73 m2/year) was evaluated using the multivariate regression model. Results During the 2.35-year follow-up, the incidence of RFD was 7.30%. The rAIp75 had no statistically independent association with RFD after adjustment for possible confounders (adjusted odds ratio = 1.12, 95% confidence interval: 0.99–1.27, p = 0.074). When stratified according to sex, the rAIp75 was significantly associated with RFD in women, but not in men (adjusted odds ratio and 95% confidence interval: 1.23[1.06–1.43], p = 0.007 for women, 0.94[0.76–1.16], p = 0.542 for men; p for interaction = 0.038). Conclusion The rAI might help screen for those at high risk of early rapid RFD in women without CKD.


2021 ◽  
Vol 9 ◽  
pp. 205031212110245
Author(s):  
Getu Mosisa ◽  
Bikila Regassa ◽  
Bayise Biru

Introduction: Hypertension remains an emerging public health problem globally, particularly in developing countries. Age, income level, obesity, alcohol consumption, smoking, vegetables and fruit consumption, physical activity and chat chewing were some risk factors of hypertension. However, there are limited data on the epidemiology of hypertension in Ethiopia. This study aimed to assess Epidemiology of Hypertension among the community of selected towns of Wollega zones. Methods: A community-based cross-sectional study was conducted from 1 to 30 June 2019 in selected towns of Wollega zones. A multistage sampling technique was used to select 840 study participants. Data were collected using the WHO STEP wise approach. The data were coded and entered into EpiData 3, and exported to SPSS version 20.0 for analysis. Bivariate and multivariable logistic regression analyses were conducted. Statistical significance was declared at p-value < 0.05. Results: The study included a total of 838 respondents with a response rate of 99.7%. The prevalence of hypertension was found to be 189 (22.6%) (95% confidence interval = 19.9%–25.2%). Of this, 108 (12.9%) and 81 (9.7%) of female and male were hypertensive, respectively. Age groups of 30–44 years (adjusted odds ratio = 2.65 (1.43, 4.89)), 45–59 years (adjusted odds ratio = 3.55 (1.79, 7.04)), above 60 years (adjusted odds ratio = 2.97 (1.43, 6.18)), having history of alcohol consumption (adjusted odds ratio = 4.29 (2.4, 7.66)), involving in vigorous physical activity (adjusted odds ratio = 0.096 (0.028, 0.33)), not walking to and from the work (adjusted odds ratio = 13.12 (8.34, 20.67)), being overweight (adjusted odds ratio = 1.98 (1.21, 3.25)), inadequate fruits serving per day (adjusted odds ratio = 2.93 (1.75, 4.88)) were significantly associated with hypertension. Conclusion: The prevalence of hypertension was found to be high in the study area. Older age, alcohol consumption, not engaging in vigorous activity, physical inactivity, being overweight and inadequate intake of fruits were found to be risk factors for hypertension. Therefore, health care providers should provide extensive health education and promotion on recommended lifestyle modification to tackle the burden of hypertension.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sara C. Auld ◽  
Hardy Kornfeld ◽  
Pholo Maenetje ◽  
Mandla Mlotshwa ◽  
William Chase ◽  
...  

Abstract Background While tuberculosis is considered a risk factor for chronic obstructive pulmonary disease, a restrictive pattern of pulmonary impairment may actually be more common among tuberculosis survivors. We aimed to determine the nature of pulmonary impairment before and after treatment among people with HIV and tuberculosis and identify risk factors for long-term impairment. Methods In this prospective cohort study conducted in South Africa, we enrolled adults newly diagnosed with HIV and tuberculosis who were initiating antiretroviral therapy and tuberculosis treatment. We measured lung function and symptoms at baseline, 6, and 12 months. We compared participants with and without pulmonary impairment and constructed logistic regression models to identify characteristics associated with pulmonary impairment. Results Among 134 participants with a median CD4 count of 110 cells/μl, 112 (83%) completed baseline spirometry at which time 32 (29%) had restriction, 13 (12%) had obstruction, and 9 (7%) had a mixed pattern. Lung function was dynamic over time and 30 (33%) participants had impaired lung function at 12 months. Baseline restriction was associated with greater symptoms and with long-term pulmonary impairment (adjusted odds ratio 5.44, 95% confidence interval 1.16–25.45), while baseline obstruction was not (adjusted odds ratio 1.95, 95% confidence interval 0.28–13.78). Conclusions In this cohort of people with HIV and tuberculosis, restriction was the most common, symptomatic, and persistent pattern of pulmonary impairment. These data can help to raise awareness among clinicians about the heterogeneity of post-tuberculosis pulmonary impairment, and highlight the need for further research into mediators of lung injury in this vulnerable population.


2020 ◽  
Vol 41 (S1) ◽  
pp. s339-s340
Author(s):  
Roopali Sharma ◽  
Deepali Dixit ◽  
Sherin Pathickal ◽  
Jenny Park ◽  
Bernice Lee ◽  
...  

Background: Data from Clostridium difficile infection (CDI) in neutropenic patients are still scarce. Objective: To assess outcomes of CDI in patients with and without neutropenia. Methods: The study included a retrospective cohort of adult patients at 3 academic hospitals between January 2013 and December 2017. The 2 study arms were neutropenic patients (neutrophil count <500/mm3) and nonneutropenic patients with confirmed CDI episodes. The primary outcome evaluated the composite end point of all-cause in-hospital mortality, intensive care unit (ICU) admissions, and treatment failure at 7 days. The secondary outcome evaluated hospital length of stay. Results: Of 962 unique cases of CDI, 158 were neutropenic (59% men) and 804 were nonneutropenic (46% men). The median age was 57 years (IQR, 44–64) in the neutropenic group and 68 years (IQR, 56–79) in the nonneutropenic group. The median Charlson comorbidity score was 5 (IQR, 3–7.8) and 4 (IQR, 3–5) in the neutropenic and nonneutropenic groups, respectively. Regarding severity, 88.6% versus 48.9% were nonsevere, 8.2% versus 47% were severe, and 3.2% versus 4.1% were fulminant in the neutropenic and nonneutropenic groups, respectively. Also, 63% of patients (60.9% in nonneutropenic, 65.2% in neutropenic) were exposed to proton-pump inhibitors. A combination CDI treatment was required in 53.2% of neutropenic patients and 50.1% of nonneutropenic patients. The primary composite end point occurred in 27% of neutropenic patients versus 22% of nonneutropenic patients (P = .257), with an adjusted odds ratio of 1.30 (95% CI, 0.84–2.00). The median hospital length of stay after controlling for covariates was 21.3 days versus 14.2 days in the neutropenic and nonneutropenic groups, respectively (P < .001). Complications (defined as hypotension requiring vasopressors, ileus, or bowel perforation) were seen in 6.0% of the nonneutropenic group and 4.4% of the neutropenic group (P = .574), with an adjusted odds ratio of 0.61 (95% CI, 0.28–1.45). Conclusions: Neutropenic patients were younger and their cases were less severe; however, they had lower incidences of all-cause in-hospital mortality, ICU admissions, and treatment failure. Hospital length of stay was significantly shorter in the neutropenic group than in the nonneutropenic group.Funding: NoneDisclosures: None


Author(s):  
Daiki Sakai ◽  
Wataru Matsumiya ◽  
Sentaro Kusuhara ◽  
Makoto Nakamura

Abstract Purpose To evaluate the factors associated with the development of ocular candidiasis (OC) and ocular prognosis with echinocandin therapy for candidemia. Methods The medical records of 56 consecutive patients with a positive blood culture for Candida species between November 2016 and October 2019 were retrospectively reviewed. Information on patient characteristics, isolated Candida species, treatment details for candidemia, and ocular findings were extracted to identify factors associated with OC development. Results The leading pathogen of candidemia was Candida albicans (C.albicans) (41.1%). Of 56 patients, 18 (32.1%) were diagnosed with chorioretinitis, categorized as either probable (8 patients) or possible OC (10 patients). There was no case of endophthalmitis with vitritis. The incidence of probable OC was not significantly different between the groups treated with echinocandins and other antifungal drugs (15.2% vs. 11.1%, p = 1.00). In all probable OC cases, systemic antifungal therapy was switched from echinocandins to azoles, and no case progressed to endophthalmitis. A multivariate logistic analysis revealed that female sex (adjusted odds ratio [aOR], 8.93; 95% confidence interval [CI], 1.09–72.9) and C. albicans (aOR, 23.6; 95% CI, 1.8–281) were independent factors associated with the development of probable OC. Conclusion One-seventh of patients with candidemia developed probable OC. Given the evidence of female and C. albicans as the factors associated with OC development, careful ophthalmologic management is required with these factors, especially in candidemia. Although echinocandins had no correlation with OC development and did not lead to the deterioration of ocular prognosis, further investigation is required.


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S11-S12
Author(s):  
Zachary Hostetler ◽  
Keith W Hamilton ◽  
Leigh Cressman ◽  
McWelling H Todman ◽  
Ebbing Lautenbach ◽  
...  

Abstract Background Inappropriate prescription of antibiotics for respiratory tract infections (RTIs) in ambulatory care settings is common, increasing the risk of adverse health outcomes. Behavioral and educational interventions targeting primary care providers (PCPs) have shown promise in reducing inappropriate antibiotic prescribing for RTIs. While one perceived barrier to such interventions is the concern that these adversely impact patient satisfaction, few data exist in this area. Here, we examine whether a recent PCP-targeted intervention that significantly reduced antibiotic prescribing for RTIs was associated with a change in patient satisfaction. Methods The PCP-targeted intervention involved monthly education sessions and peer benchmarking reports delivered to 31 clinics within an academic health system, and was previously shown to reduce antibiotic prescribing. Here, we performed a retrospective, secondary analysis of Press Ganey (PG) surveys associated with the outpatient encounters in the pre- and post-intervention periods. We evaluated the impact on patient perceptions of PCPs based on provider exposure to the intervention using a mixed effects logistic regression model. Results There were 17,416 out of 197,744 encounters (8.8%) with associated PG surveys for the study time period (July 2016 to September 2018). In the multivariate model, patient satisfaction with PCPs was most strongly associated with patient-level characteristics (age, race, health status, education status) and survey-level characteristics (survey response time, patient’s usual provider) (Figure 1). Satisfaction with PCPs did not change following delivery of the provider-based intervention even after adjusting for patient- and survey-level characteristics [adjusted odds ratio (95% CI): 1.005 (0.928, 1.087)]. However, a small increase in satisfaction associated with receiving antibiotics during the entire study period was seen [adjusted odds ratio (95% CI): 1.146 (1.06, 1.244)]. Figure 1: Association of a provider-targeted intervention as well as patient, provider, and practice characteristics with patient satisfaction in a multivariable mixed effects logistic regression model Conclusion Patient perceptions of PCPs remain unchanged following the delivery of a behavioral and educational intervention to primary care providers that resulted in observable decreases in antibiotic prescribing practices for RTIs. Disclosures All Authors: No reported disclosures


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