Cox Regression Models with Time-Varying Covariates Applied to Survival Success of Young Firms

2013 ◽  
Vol 3 (2) ◽  
pp. 53-69 ◽  
Author(s):  
Aygul Anavatan ◽  
Murat Karaoz
Keyword(s):  
Regression Models ◽  
Cox Regression ◽  
Time Varying ◽  
Young Firms ◽  
Time Varying Covariates

scholarly journals Risk Factors for Patient–Ventilator Asynchrony and Its Impact on Clinical Outcomes: Analytics Based on Deep Learning Algorithm

2020 ◽  
Vol 7 ◽  
Author(s):  
Huiqing Ge ◽  
Kailiang Duan ◽  
Jimei Wang ◽  
Liuqing Jiang ◽  
Lingwei Zhang ◽  
...  
Keyword(s):  
Risk Factors ◽  
Tidal Volume ◽  
Clinical Outcomes ◽  
Regression Models ◽  
Negative Binomial ◽  
Cox Regression ◽  
Plateau Pressure ◽  
Care Hospital ◽  
Time Varying ◽  
Time Varying Covariates

Background and objectives: Patient–ventilator asynchronies (PVAs) are common in mechanically ventilated patients. However, the epidemiology of PVAs and its impact on clinical outcome remains controversial. The current study aims to evaluate the epidemiology and risk factors of PVAs and their impact on clinical outcomes using big data analytics.Methods: The study was conducted in a tertiary care hospital; all patients with mechanical ventilation from June to December 2019 were included for analysis. Negative binomial regression and distributed lag non-linear models (DLNM) were used to explore risk factors for PVAs. PVAs were included as a time-varying covariate into Cox regression models to investigate its influence on the hazard of mortality and ventilator-associated events (VAEs).Results: A total of 146 patients involving 50,124 h and 51,451,138 respiratory cycles were analyzed. The overall mortality rate was 15.6%. Double triggering was less likely to occur during day hours (RR: 0.88; 95% CI: 0.85–0.90; p < 0.001) and occurred most frequently in pressure control ventilation (PCV) mode (median: 3; IQR: 1–9 per hour). Ineffective effort was more likely to occur during day time (RR: 1.09; 95% CI: 1.05–1.13; p < 0.001), and occurred most frequently in PSV mode (median: 8; IQR: 2–29 per hour). The effect of sedatives and analgesics showed temporal patterns in DLNM. PVAs were not associated mortality and VAE in Cox regression models with time-varying covariates.Conclusions: Our study showed that counts of PVAs were significantly influenced by time of the day, ventilation mode, ventilation settings (e.g., tidal volume and plateau pressure), and sedatives and analgesics. However, PVAs were not associated with the hazard of VAE or mortality after adjusting for protective ventilation strategies such as tidal volume, plateau pressure, and positive end expiratory pressure (PEEP).

scholarly journals Time-varying covariates and coefficients in Cox regression models

2018 ◽  
Vol 6 (7) ◽  
pp. 121-121 ◽  
Author(s):  
Zhongheng Zhang ◽  
Jaakko Reinikainen ◽  
Kazeem Adedayo Adeleke ◽  
Marcel E. Pieterse ◽  
Catharina G. M. Groothuis-Oudshoorn
Keyword(s):  
Regression Models ◽  
Cox Regression ◽  
Time Varying ◽  
Time Varying Covariates

scholarly journals P1462IMPACT OF HEART RATE AND BETA-BLOCKER USE ON THE LONG-TERM SURVIVAL OF CHRONIC HEMODIALYSIS PATIENTS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Takuhiro Moromizato ◽  
Kunitoshi Iseki ◽  
OCTOPUS Study Group
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cox Regression ◽  
Chronic Hemodialysis ◽  
Time Varying ◽  
Term Survival ◽  
Blood Pressures ◽  
Β Blocker ◽  
Time Varying Covariates

Abstract Background and Aims Increase in resting heart rate might influence mortalities of dialysis patients, and the use of β-blocker might improve their survival probability. However, the influence of heart rate and benefits of β-blocker on their survival are difficult to quantify because of following obstacles: prone to measurement errors; inherent association of heart rate with blood pressures, comorbidities, and medication use; and a necessity of repeated measurements of vital signs and medication use. Therefore, at the design process of our previous randomized control trial on the Olmesartan Clinical Trial in Okinawan patients under OKIDS (OCTOPUS), we included the repeated measures design to quantify the influence of vital sign values on the survival retrospectively. We combined the repeated measurement data and additional the long-term prognosis information of the participants obtained after the OCTOPUS with aim of investigating the influence of time varying covariates: heart rates, blood pressures, and β-blocker use, on the long-term survival of hemodialysis patients. Method We investigated 461 adult OCTOPUS participants who received chronic hemodialysis and antihypertensive medications in Okinawa. The OCTOPUS trial, which was conducted between June 2006 and June 2011, did not detect the survival benefit of angiotensin receptor blocker (ARB)NDT 2013, but the study and the additional follow-up of participants’ prognosis provided us with information to investigate influence of predictors on long-term survival in the population. Throughout the OCTOPUS trial, study participants were measured pre-dialysis blood pressures, pre-dialysis resting heart rates, and their medication use for one week at their dialysis centers every six months after their participations. Following the trial, we collected the prognosis information of all participants until July 31st, 2018. Finally, we merged the multiple-measured data during the OCTOPUS with the prognosis data. Mean values of three measurements of blood pressures and heart rates and β-blocker use were introduced to the Cox-regression model as time-varying covariates with essential non-time varying covariates, which include age, gender, and diabetes. Results In this retrospective cohort study, 221 (47.9%) out of 461 participants deceased, and the median follow-up length was 10.21 years. Initial mean resting heart rate and pre-dialysis mean blood pressure were 78(±10) per minute and 159.5(±14) mmHg, respectively. 10% of participants were prescribed β-blocker initially. The resting heart rate of all participants significantly decreased by 1.75 and 2.45 per minutes after two and four years respectively. β-blocker could significantly decrease the mean heart rate by 3.54 and 2.90 per minutes after two and four years. With our Cox-regression with the time varying covariates, increase of heart rate was significantly associated with higher mortality (P=0.002), but the use of β-blocker was not associated with the mortality. (P=0.691) Additionally, we could not detect the interaction of heart rate and β-blocker use on the mortality. (P= 0.796) Although lower blood pressure was significantly associated with higher mortality in our initial Cox-regression analysis, an introduction of interaction term of heart rate and blood pressure remove the significance of influence of blood pressure on the survival. Conclusion In hypertensive chronic hemodialysis patients, higher heart rate is associated with higher mortality. However, use of beta-blocker was not associated with improvement of their mortality.

Physical activity and sedentary behaviour over adulthood in relation to all-cause and cause-specific mortality: a systematic review of analytic strategies and study findings

2021 ◽  
Author(s):  
Yi Yang ◽  
Suzanne C Dixon-Suen ◽  
Pierre-Antoine Dugué ◽  
Allison M Hodge ◽  
Brigid M Lynch ◽  
...  
Keyword(s):  
Physical Activity ◽  
Sedentary Behaviour ◽  
Cox Regression ◽  
Risk Of Bias ◽  
Multiple Time ◽  
Time Varying ◽  
Relative Risks ◽  
Specific Mortality ◽  
Multiple Time Points ◽  
Time Varying Covariates

Abstract Background Questions remain about the effect on mortality of physical activity and sedentary behaviour over time. We summarized the evidence from studies that assessed exposure from multiple time points and critiqued the analytic approaches used. Methods A search was performed on MEDLINE, Embase, Emcare, Scopus and Web of Science up to January 2021 for studies of repeatedly assessed physical activity or sedentary behaviour in relation to all-cause or cause-specific mortality. Relative risks from individual studies were extracted. Each study was assessed for risk of bias from multiple domains. Results We identified 64 eligible studies (57 on physical activity, 6 on sedentary behaviour, 1 on both). Cox regression with a time-fixed exposure history (n = 45) or time-varying covariates (n = 13) were the most frequently used methods. Only four studies used g-methods, which are designed to adjust for time-varying confounding. Risk of bias arose primarily from inadequate adjustment for time-varying confounders, participant selection, exposure classification and changes from measured exposure. Despite heterogeneity in methods, most studies found that being consistently or increasingly active over adulthood was associated with lower all-cause and cardiovascular-disease mortality compared with being always inactive. Few studies examined physical-activity changes and cancer mortality or effects of sedentary-behaviour changes on mortality outcomes. Conclusions Accumulating more evidence using longitudinal data while addressing the methodological challenges would provide greater insight into the health effects of initiating or maintaining a more active and less sedentary lifestyle.

scholarly journals FRI0066 SUBCLINICAL CORONARY CALCIFICATION ASSOCIATED WITH LONG-TERM CARDIOVASCULAR OUTCOMES IN RHEUMATOID ARTHRITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 609.1-610
Author(s):  
G. Karpouzas ◽  
S. Ormseth ◽  
E. Hernandez ◽  
M. Budoff
Keyword(s):  
Rheumatoid Arthritis ◽  
Cardiovascular Disease ◽  
Cardiovascular Event ◽  
Cardiovascular Events ◽  
Regression Models ◽  
Time Varying ◽  
Event Risk ◽  
The Impact ◽  
Time Varying Covariates

Background:Large, multicenter studies established the strong prognostic value of coronary artery calcium (CAC) scoring in asymptomatic individuals. Increasing CAC score is an independent predictor of worsening cardiovascular disease event risk in general patients. The prognostic significance of higher CAC score strata in the long-term cardiovascular risk in rheumatoid arthritis (RA) is unknown.Objectives:To evaluate the long-term cardiovascular event risk across CAC strata in a prospective, single center cohort of established RA patients without symptoms or prior diagnosis of cardiovascular disease.Methods:One hundred-fifty patients underwent computed tomography angiography for coronary atherosclerosis evaluation. CAC score was measured according to Agatston. CVD events were prospectively recorded, including cardiac death, myocardial infarction, unstable angina, revascularization, stroke, claudication, and heart failure hospitalization over 6.0±2.4 years of follow-up. Unadjusted, robust Cox proportional hazards regression models evaluated CVD event risk across higher CAC strata (CAC=1-99, CAC=100-399 and CAC≥400) compared to CAC=0. Additional multivariable robust Cox regression models with time-varying covariates evaluated the impact of log transformed CAC or different CAC thresholds (CAC>0 vs. CAC=0, CAC≥100 vs. CAC<100 and CAC≥400 vs. CAC<400) on future CVD events. Models were controlled for Framingham-D’Agostino clinical risk score, time-varying current bDMARD use and time-varying CRP.Results:Sixteen patients incurred 19 events, for a total of 2.1 (95% CI 1.3-3.3) events/100 patient-years. Increasing HR for cardiovascular events was observed for ascending CAC strata; 3.87 (1.03-14.48), 6.31 (1.38-28.91) and 16.98 (4.50-64.10) for CAC=1-99, CAC=100-399 and CAC≥400 respectively compared to CAC=0 (figure 1). In fully adjusted models, CAC score associated with future event risk independently of Framingham D’Agostino score, time-varying bDMARD use and time-varying CRP (HR=1.31 [95%CI 1.04-1.66]). CAC thresholds ≥100 (vs. <100) and CAC≥400 (vs. <400) in fully adjusted models similarly constituted independent predictors of long-term cardiovascular events (Figure 2).Figure 1.Increasing CAC scores associated with higher cardiovascular event risk in RAFigure 2.Impact of different CAC thresholds on cardiovascular event risk in RAConclusion:Increasing CAC scores are strong, independent predictors of long-term cardiovascular events in RA patients without symptoms or prior diagnosis of cardiovascular disease.Disclosure of Interests:George Karpouzas Grant/research support from: Pfizer, Consultant of: Sanofi-Genzyme-Regeneron, Janssen, Speakers bureau: Sanofi-Genzyme-Regeneron, BMS, Sarah Ormseth: None declared, Elizabeth Hernandez: None declared, Matthew Budoff: None declared

scholarly journals Prediction of COPD risk accounting for time-varying smoking exposures

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248535
Author(s):  
Joanne T. Chang ◽  
Rafael Meza ◽  
David T. Levy ◽  
Douglas Arenberg ◽  
Jihyoun Jeon
Keyword(s):  
Prediction Model ◽  
Risk Prediction ◽  
Cox Regression ◽  
The United States ◽  
Risk Prediction Model ◽  
Health Study ◽  
Time Varying ◽  
Smoking Duration ◽  
Summary Measures ◽  
Time Varying Covariates

Rationale Chronic Obstructive Pulmonary Disease (COPD) is the fourth leading cause of death in the United States. Studies have primarily assessed the relationship between smoking on COPD risk focusing on summary measures, like smoking status. Objective Develop a COPD risk prediction model incorporating individual time-varying smoking exposures. Methods The Nurses’ Health Study (N = 86,711) and the Health Professionals Follow-up Study (N = 39,817) data was used to develop a COPD risk prediction model. Data was randomly split in 50–50 samples for model building and validation. Cox regression with time-varying covariates was used to assess the association between smoking duration, intensity and year-since-quit and self-reported COPD diagnosis incidence. We evaluated the model calibration as well as discriminatory accuracy via the Area Under the receiver operating characteristic Curve (AUC). We computed 6-year risk of COPD incidence given various individual smoking scenarios. Results Smoking duration, year-since-quit (if former smokers), sex, and interaction of sex and smoking duration are significantly associated with the incidence of diagnosed COPD. The model that incorporated time-varying smoking variables yielded higher AUCs compared to models using only pack-years. The AUCs for the model were 0.80 (95% CI: 0.74–0.86) and 0.73 (95% CI: 0.70–0.77) for males and females, respectively. Conclusions Utilizing detailed smoking pattern information, the model predicts COPD risk with better accuracy than models based on only smoking summary measures. It might serve as a tool for early detection programs by identifying individuals at high-risk for COPD.

Clinical and Demographic Characteristics of Erosion-free and Erosion-present Status in Psoriatic Arthritis in a Cohort Study

2016 ◽  
Vol 43 (6) ◽  
pp. 1057-1062 ◽  
Author(s):  
Zahi Touma ◽  
Arane Thavaneswaran ◽  
Vinod Chandran ◽  
Fawnda Pellett ◽  
Richard J. Cook ◽  
...  
Keyword(s):  
Psoriatic Arthritis ◽  
Regression Models ◽  
Cox Regression ◽  
Erosive Disease ◽  
Radiographic Findings ◽  
Logistic Regression Models ◽  
Younger Age ◽  
The Mean ◽  
Time Varying Covariates ◽  
Mean Time

Objective.Psoriatic arthritis (PsA) has been recognized as a severe erosive disease. However, some patients do not develop erosions. We aimed to determine the prevalence, characteristics, and predictors of erosion-free patients (EFP) as compared with erosion-present patients (EPP) among patients with PsA followed prospectively.Methods.This is a retrospective analysis conducted on patients from the Toronto PsA cohort. Patients with at least 10 years of followup and radiographs were analyzed. Radiographs were scored with the modified Steinbrocker method. Baseline (first visit to clinic) characteristics were used to predict the development of erosions with logistic regression models. To examine the effect of time-varying covariates, Cox regression models were fit for the time to development of erosions from baseline.Results.Among 290 patients, 12.4% were EFP and 87.6% were EPP over the study period. The mean time to development of erosion in the EPP over the course of followup was 6.8 ± 6.1 years. EFP were diagnosed with psoriasis at a younger age compared with EPP. In both models, actively inflamed joints and clinically damaged joints were predictive of the development of erosion, whereas a longer duration of psoriasis at baseline decreased the odds of developing erosion. EPP had a higher percentage of unemployment as compared with EFP at baseline and followup visits.Conclusion.Among patients with PsA followed for at least 10 years, 12.4% never develop erosions. The clinical and radiographic findings can ultimately assist in the stratification of a patient’s prognosis regarding the development of erosions.

Sign in / Sign up

Export Citation Format

Share Document