The predictors and economic burden of early-, mid- and late-onset cardiac implantable electronic device infections: a retrospective cohort study in Ontario, Canada
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Recent cohort studies in chronic obstructive pulmonary disease (COPD) have questioned the validity of previously reported associations between inhaled corticosteroids (ICS) and reductions in mortality and rehospitalization in observational studies. Using time-dependent versions of statistical survival models, these studies have suggested immortal time bias as responsible for the proposed beneficial association.We explored the extent of this bias in a study of patients with COPD monitored for a year from COPD discharge with two designs free of any immortal time bias in the General Practice Research Database in the United Kingdom.In Design 1, we used only patients whose treatment status was defined on the same day of discharge to obtain a matched cohort based on propensity scores, which were derived from the patient-level baseline characteristics. In Design 2, we identified all in the study cohort who experienced death or rehospitalization and then matched each case to up to four noncases by randomly sampling from the cohort risk sets without regard to treatment status.The propensity scores matched cohort analysis of 786 patients without a wait time found a significant risk reduction associated with use of ICS: hazard ratio, 0.69 (95% confidence interval, 0.52-0.93). The matched nested case-control analysis of 2,222 patients, designed without regard to exposure status and hence free of immortal time bias, gave a similar association with exposure to ICS in the last 6-month period: hazard ratio, 0.71 (0.56-0.90).We conclude that immortal time bias cannot account for the risk reduction associated with ICS exposure in observational studies.
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Background and objectives
Sedentary behavior is associated with increased mortality in the general population. Whether replacing sedentary behavior with low- or light-intensity activities confers a survival benefit in the general or CKD populations is unknown.Design, setting, participants, & measurements
This observational analysis of the 2003–2004 National Health and Nutrition Examination Survey examined the associations of low- and light-intensity activities with mortality. On the basis of the number of counts/min recorded by an accelerometer, durations of sedentary (<100/min), low (100–499/min), light (500–2019/min), and moderate/vigorous (≥2020/min) activity were defined and normalized to 60 minutes. The mortality associations of 2 min/hr less sedentary duration in conjunction with 2 min/hr more (tradeoff) spent in one of the low, light, or moderate/vigorous activity durations while controlling for the other two activity durations were examined in multivariable Cox regression models in the entire cohort and in the CKD subgroup.Results
Of the 3626 participants included, 383 had CKD. The mean sedentary duration was 34.4±7.9 min/hr in the entire cohort and 40.8±6.8 in the CKD subgroup. Tradeoff of sedentary duration with low activity duration was not associated with mortality in the entire cohort or the CKD subgroup. Tradeoff of sedentary duration with light activity duration was associated with a lower hazard of death in the entire cohort (hazard ratio, 0.67; 95% confidence interval, 0.48 to 0.93) and CKD subgroup (hazard ratio, 0.59; 95% confidence interval, 0.35 to 0.98). Tradeoff of sedentary duration with moderate/vigorous activity duration had a nonsignificant lower hazard in the entire cohort and CKD subgroup.Conclusions
Patients with CKD are sedentary nearly two thirds of the time. Interventions that replace sedentary duration with an increase in light activity duration might confer a survival benefit.Subgroup analysis
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Background Although most people with relapsing onset multiple sclerosis (R-MS) eventually transition to secondary progressive multiple sclerosis (SPMS), little is known about disability progression in SPMS. Methods All R-MS patients in the Cardiff MS registry were included. Cox proportional hazards regression was used to examine a) hazard of converting to SPMS and b) hazard of attaining EDSS 6.0 and 8.0 in SPMS. Results 1611 R-MS patients were included. Older age at MS onset (hazard ratio [HR] 1.02, 95%CI 1.01–1.03), male sex (HR 1.71, 95%CI 1.41–2.08), and residual disability after onset (HR 1.38, 95%CI 1.11–1.71) were asso- ciated with increased hazard of SPMS. Male sex (EDSS 6.0 HR 1.41 [1.04–1.90], EDSS 8.0 HR 1.75 [1.14–2.69]) and higher EDSS at SPMS onset (EDSS 6.0 HR 1.31 [1.17–1.46]; EDSS 8.0 HR 1.38 [1.19–1.61]) were associated with increased hazard of reaching disability milestones, while older age at SPMS was associated with a lower hazard of progression (EDSS 6.0 HR 0.94 [0.92–0.96]; EDSS 8.0: HR 0.92 [0.90–0.95]). Conclusions Different factors are associated with hazard of SPMS compared to hazard of disability progres- sion after SPMS onset. These data may be used to plan services, and provide a baseline for comparison for future interventional studies and has relevance for new treatments for SPMS RobertsonNP@cardiff.ac.uk
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Background: Patients waiting for intensive care unit (ICU) admission cause emergency department (ED) crowding and have an increased risk of mortality and length of stay (LOS) in hospital, which increase the hospitalization cost. This study aimed to investigate the correlation between mortality and invasive mechanical ventilation (IMV) time in patients in the ED. Methods: A retrospective cohort study was conducted in patients who received IMV in the ED of Ramathibodi Hospital. The correlation between mortality at 28 days after intubation and IMV time in the ED was analyzed. The cutoff time was analyzed to determine prolonged and nonprolonged IMV times. ICU ventilation time, length of ICU stay, and LOS in the hospital were also analyzed to determine their correlations between IMV time in the ED. Results: In this study, 302 patients were enrolled, 71 died, and 231 survived 28 days after receiving IMV in the ED. We found that the duration of >12 h of IMV in the ED increased the 28-day mortality rate by 1.98 times ( P = 0.036). No correlations were found between IMV time in the ED and ventilation time in the ICU, length of ICU stay, and LOS in the hospital. Conclusion: More than 12 h of IMV time in the ED correlated with mortality at 28 days after initiation of IMV. No associations were found between prolonged IMV time in the ED with ventilation time in the ICU, length of ICU stay, and LOS in the hospital.
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Summary Background and objectives Rates of hospitalization are known to be high in patients with kidney disease. However, ongoing risks of subsequent hospitalization and mortality are uncertain. The primary objective was to evaluate patients with kidney disease for long-term risks of subsequent hospitalization, including admissions resulting in death. Design, setting, participants, & measurements Patients hospitalized in Washington State between April of 2006 and December of 2008 who survived to discharge ( n =676,343) were classified by International Classification of Disease codes into CKD ( n =27,870), dialysis ( n =6131), kidney transplant ( n =1100), and reference ( n =641,242) cohorts. Cox proportional hazard models controlling for age, sex, payer, comorbidity, previous hospitalization, primary diagnosis category, and length of stay were conducted for time to event analyses. Results Compared with the reference cohort, risks for subsequent hospitalization were increased in the CKD (hazard ratio=1.20, 99% confidence interval=1.18–1.23, P <0.001), dialysis (hazard ratio=1.76, 99% confidence interval=1.69–1.83, P <0.001), and kidney transplant (hazard ratio=1.85, 99% confidence interval=1.68–2.03, P <0.001) cohorts, with a mean follow-up time of 29 months. Similarly, risks for fatal hospitalization were increased for patients in the CKD (hazard ratio=1.41, 99% confidence interval=1.34–1.49, P <0.001), dialysis (hazard ratio=3.04, 99% confidence interval=2.78–3.31, P <0.001), and kidney transplant (hazard ratio=2.25, 99% confidence interval=1.67–3.03, P <0.001) cohorts. Risks for hospitalization and fatal hospitalization increased in a graded manner by CKD stage. Conclusions Risks of subsequent hospitalization, including admission resulting in death, among patients with kidney disease were substantially increased in a large statewide population. Patients with kidney disease should be a focus of efforts to reduce hospitalizations and mortality.
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The hazard ratio and median survival time are the routine indicators in survival analysis. We briefly introduced the relationship between hazard ratio and median survival time and the role of proportional hazard assumption. We compared 110 pairs of hazard ratio and median survival time ratio in 58 articles and demonstrated the reasons for the difference by examples. The results showed that the hazard ratio estimated by the Cox regression model is unreasonable and not equivalent to median survival time ratio when the proportional hazard assumption is not met. Therefore, before performing the Cox regression model, the proportional hazard assumption should be tested first. If proportional hazard assumption is met, Cox regression model can be used; if proportional hazard assumption is not met, restricted mean survival times is suggested.风险比（hazard ratio，HR）和中位生存时间是生存分析时的常规分析和报告指标。本文简要介绍了HR和中位生存时间的关系以及比例风险假定在这两者之间的作用，分析了检索出的58篇文献中的110对风险比和中位生存时间比的差异，并通过实例阐明了产生这种差异的原因。结果表明，在不满足比例风险假定时，Cox回归模型计算得到的风险比是不合理的，且与中位生存时间之比不等价。因此，在使用Cox回归模型前，应先进行比例风险假定的检验，只有符合比例风险假定时才能使用该模型；当不符合比例风险假定时，建议使用限制性平均生存时间。.
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The application of survival analysis on the data of credit motorcycle financing experiencing bad loans after the credit starts early, with sixteen covariates were considered. The model used in survival analysis is the Cox proportional hazard models. Cox models have the assumption that the proportional hazard assumption. Extended Cox models selected to improve cox proportional hazard models when one or more covariates did not meet the assumption of proportional hazards. Extended cox models is an extension of cox models that involve time-dependent variables. Covariates that do not meet the proportional hazards assumption in the Cox models diinteraksikan extended with functions appropriate time, in order to obtain time-dependent covariates. So on the model covariates that are not dependent on time and time dependent covariates. The parameters of these covariates estimated using partial maximum likelihood method. To determine whether the extended Cox model is a suitable model for the data in a particular case, likelihood ratio test was used. The results indicate that extended Cox models with functions time appropriate, provide the best model.Keywords : Credit Risk, Survival Analysis, Cox Proportional Hazard , Extended Cox Model
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Pulse oximetry is routinely used to continuously and noninvasively monitor arterial oxygen saturation (SaO2) in critically ill patients. Although pulse oximeter oxygen saturation (SpO2) has been studied in several patient populations, including the critically ill, its accuracy has never been studied in emergency department (ED) patients with severe sepsis and septic shock. Sepsis results in characteristic microcirculatory derangements that could theoretically affect pulse oximeter accuracy. The purposes of the present study were twofold: 1) to determine the accuracy of pulse oximetry relative to SaO2 obtained from ABG in ED patients with severe sepsis and septic shock, and 2) to assess the impact of specific physiologic factors on this accuracy.This analysis consisted of a retrospective cohort of 88 consecutive ED patients with severe sepsis who had a simultaneous arterial blood gas and an SpO2 value recorded. Adult ICU patients that were admitted from any Calgary Health Region adult ED with a pre-specified, sepsis-related admission diagnosis between October 1, 2005 and September 30, 2006, were identified. Accuracy (SpO2 - SaO2) was analyzed by the method of Bland and Altman. The effects of hypoxemia, acidosis, hyperlactatemia, anemia, and the use of vasoactive drugs on bias were determined.The cohort consisted of 88 subjects, with a mean age of 57 years (19 - 89). The mean difference (SpO2 - SaO2) was 2.75% and the standard deviation of the differences was 3.1%. Subgroup analysis demonstrated that hypoxemia (SaO2 < 90) significantly affected pulse oximeter accuracy. The mean difference was 4.9% in hypoxemic patients and 1.89% in non-hypoxemic patients (p < 0.004). In 50% (11/22) of cases in which SpO2 was in the 90-93% range the SaO2 was <90%. Though pulse oximeter accuracy was not affected by acidoisis, hyperlactatementa, anemia or vasoactive drugs, these factors worsened precision.Pulse oximetry overestimates ABG-determined SaO2 by a mean of 2.75% in emergency department patients with severe sepsis and septic shock. This overestimation is exacerbated by the presence of hypoxemia. When SaO2 needs to be determined with a high degree of accuracy arterial blood gases are recommended.
Pulse Oximetry
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