scholarly journals A fast and efficient smoothing approach to Lasso regression and an application in statistical genetics: polygenic risk scores for chronic obstructive pulmonary disease (COPD)

2021 ◽  
Vol 31 (3) ◽  
Author(s):  
Georg Hahn ◽  
Sharon M. Lutz ◽  
Nilanjana Laha ◽  
Michael H. Cho ◽  
Edwin K. Silverman ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Statistical Genetics ◽  
Risk Scores ◽  
Chronic Obstructive ◽  
Lasso Regression ◽  
Obstructive Pulmonary Disease ◽  
Polygenic Risk

scholarly journals A fast and efficient smoothing approach to Lasso regression and an application in statistical genetics: polygenic risk scores for chronic obstructive pulmonary disease (COPD)

2020 ◽  
Author(s):  
Georg Hahn ◽  
Sharon M. Lutz ◽  
Nilanjana Laha ◽  
Michael H. Cho ◽  
Edwin K. Silverman ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Objective Function ◽  
Closed Form ◽  
Pulmonary Disease ◽  
Gradient Descent ◽  
Risk Scores ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Polygenic Risk ◽  
A Genome

AbstractHigh dimensional linear regression problems are often fitted using Lasso approaches. Although the Lasso objective function is convex, it is not differentiable everywhere, making the use of gradient descent methods for minimization not straightforward. To avoid this technical issue, we apply Nesterov smoothing to the original (unsmoothed) Lasso objective function. We introduce a closed-form smoothed Lasso which preserves the convexity of the Lasso function, is uniformly close to the unsmoothed Lasso, and allows us to obtain closed-form derivatives everywhere for efficient and fast minimization via gradient descent. Our simulation studies are focused on polygenic risk scores using genetic data from a genome-wide association study (GWAS) for chronic obstructive pulmonary disease (COPD). We compare accuracy and runtime of our approach to the current gold standard in the literature, the FISTA algorithm. Our results suggest that the proposed methodology provides estimates with equal or higher accuracy than the the FISTA algorithm while having the same asymptotic runtime scaling.

scholarly journals Emergency admission parameters for predicting in-hospital mortality in patients with acute exacerbations of chronic obstructive pulmonary disease with hypercapnic respiratory failure

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lan Chen ◽  
Lijun Chen ◽  
Han Zheng ◽  
Sunying Wu ◽  
Saibin Wang
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Respiratory Failure ◽  
Hospital Mortality ◽  
Pulmonary Disease ◽  
Clinical Utility ◽  
Receiver Operating Curve ◽  
Chronic Obstructive ◽  
Lasso Regression ◽  
Obstructive Pulmonary Disease ◽  
Hypercapnic Respiratory Failure

Abstract Background Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a common presentation in emergency departments (ED) that can be fatal. This study aimed to develop a mortality risk assessment model for patients presenting to the ED with AECOPD and hypercapnic respiratory failure. Methods We analysed 601 participants who were presented to an ED of a tertiary hospital with AECOPD between 2018 and 2020. Patient demographics, vital signs, and altered mental status were assessed on admission; moreover, the initial laboratory findings and major comorbidities were assessed. We used least absolute shrinkage and selection operator (LASSO) regression to identify predictors for establishing a nomogram for in-hospital mortality. Predictive ability was assessed using the area under the receiver operating curve (AUC). A 500 bootstrap method was applied for internal validation; moreover, the model’s clinical utility was evaluated using decision curve analysis (DCA). Additionally, the nomogram was compared with other prognostic models, including CRB65, CURB65, BAP65, and NEWS. Results Among the 601 patients, 19 (3.16%) died during hospitalization. LASSO regression analysis identified 7 variables, including respiratory rate, PCO2, lactic acid, blood urea nitrogen, haemoglobin, platelet distribution width, and platelet count. These 7 variables and the variable of concomitant pneumonia were used to establish a predictive model. The nomogram showed good calibration and discrimination for mortality (AUC 0.940; 95% CI 0.895–0.985), which was higher than that of previous models. The DCA showed that our nomogram had clinical utility. Conclusions Our nomogram, which is based on clinical variables that can be easily obtained at presentation, showed favourable predictive accuracy for mortality in patients with AECOPD with hypercapnic respiratory failure.

Oral and Oropharyngeal Sensory Function in Adults With Chronic Obstructive Pulmonary Disease

2020 ◽  
Vol 29 (2) ◽  
pp. 864-872
Author(s):  
Fernanda Borowsky da Rosa ◽  
Adriane Schmidt Pasqualoto ◽  
Catriona M. Steele ◽  
Renata Mancopes
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Oral Cavity ◽  
Pulmonary Disease ◽  
Thermal Sensation ◽  
Sensory Function ◽  
Control Group ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Age Related ◽  
Copd Patients

Introduction The oral cavity and pharynx have a rich sensory system composed of specialized receptors. The integrity of oropharyngeal sensation is thought to be fundamental for safe and efficient swallowing. Chronic obstructive pulmonary disease (COPD) patients are at risk for oropharyngeal sensory impairment due to frequent use of inhaled medications and comorbidities including gastroesophageal reflux disease. Objective This study aimed to describe and compare oral and oropharyngeal sensory function measured using noninstrumental clinical methods in adults with COPD and healthy controls. Method Participants included 27 adults (18 men, nine women) with a diagnosis of COPD and a mean age of 66.56 years ( SD = 8.68). The control group comprised 11 healthy adults (five men, six women) with a mean age of 60.09 years ( SD = 11.57). Spirometry measures confirmed reduced functional expiratory volumes (% predicted) in the COPD patients compared to the control participants. All participants completed a case history interview and underwent clinical evaluation of oral and oropharyngeal sensation by a speech-language pathologist. The sensory evaluation explored the detection of tactile and temperature stimuli delivered by cotton swab to six locations in the oral cavity and two in the oropharynx as well as identification of the taste of stimuli administered in 5-ml boluses to the mouth. Analyses explored the frequencies of accurate responses regarding stimulus location, temperature and taste between groups, and between age groups (“≤ 65 years” and “> 65 years”) within the COPD cohort. Results We found significantly higher frequencies of reported use of inhaled medications ( p < .001) and xerostomia ( p = .003) in the COPD cohort. Oral cavity thermal sensation ( p = .009) was reduced in the COPD participants, and a significant age-related decline in gustatory sensation was found in the COPD group ( p = .018). Conclusion This study found that most of the measures of oral and oropharyngeal sensation remained intact in the COPD group. Oral thermal sensation was impaired in individuals with COPD, and reduced gustatory sensation was observed in the older COPD participants. Possible links between these results and the use of inhaled medication by individuals with COPD are discussed.

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