IMPLEMENTASI MODEL ACCELERATED FAILURE TIME (AFT) BERDISTRIBUSI LOG-LOGISTIK PADA PASIEN PENYAKIT JANTUNG BAWAAN

Log-Logistic Accelerated Failure Time (AFT) model is survival analysis that is used when the survival time follows Log-Logistic distribution. Log-Logistic AFT model can be used to estimate survival time, survival function, and hazard function. Log-Logistic AFT model was formed by regressing covariates linierly against the log of survival time. Regression coefficients are estimated using maximum likelihood method. This study uses data from Atrial Septal Defect (ASD) patients, which is a congenital disease with a hole in the wall that separates the top of two chambers of the heart by using sensor type III. Survival time as the response variable, that is the time from patient was diagnosed with ASD until the first relapse and uses age, gender, treatment status (catheterization/surgery), defect size that is the size of the hole in the heart terrace, pulmonary hypertension status, and pain status as predictor variables. The result showed that variable gender, treatment status, defect size, pulmonary hypertension status, and pain status affect the first recurrence of ASD patients, so it is found that category of female, untreated patient, defect size ≥12mm, having pulmonary hypertension, having chest pain tend to have first recurrence sooner than the other category.

A Reserve Planning Method of Transformer Group based on Markov Reliability Model

In view of the current situation that the load difference is not considered in the existing research on public standby transformer, the reliability Markov model and public standby planning model of distribution transformer unit based on public standby mode are proposed. When the transformer fails, the standby transformer is preferred to replace the faulty transformer. The power failure time of the user is shortened from the transformer maintenance time to the standby installation and operation time. The state transition rate is the installation and operation rate of the standby transformer, and the replaced faulty transformer is converted to the standby transformer in the unavailable state. This paper applies the scheme decision analysis method to the field of engineering control, and applies the combination of the compound matter element analysis and the subjective and objective weight to the quantitative calculation of correlation entropy. This method solves the current situation that transformer faults are difficult to measure and calculate quantitatively, and it can accurately predict the healthy development trend of transformers, which has a good guiding value for the use and maintenance of transformers. At the same time, the public standby measures of distribution transformer can better solve the problem of long transformer fault repair time with a small amount of capital investment, effectively shorten the recovery time of fault outage and reduce the impact of transformer fault. The standby measures of distribution transformer have an obvious impact on the reliability of distribution system.

Impact of atrial fibrillation on in-hospital outcomes among hospitalizations for cardiac surgery: an analysis of the National Inpatient Sample

The short-term impact of atrial fibrillation (AF) on cardiac surgery hospitalizations has been previously reported in cohorts of various sizes, but results have been variable. Using the 2005–2014 National Inpatient Sample, we identified all adult hospitalizations for cardiac surgery using the International Classification of Diseases, Ninth Revision, Clinical Modification as any procedure code and AF as any diagnosis code. We estimated the impact of AF on inpatient mortality, length of stay (LOS), and cost of hospitalization using survey-weighted, multivariable logistic, accelerated failure-time log-normal, and log-transformed linear regressions, respectively. Additionally, we exact-matched AF to non-AF hospitalizations on various confounders for the same outcomes. A total of 1,269,414 hospitalizations were noted for cardiac surgery during the study period. Coexistent AF was found in 44.9% of these hospitalizations. Overall mean age was 65.6 years, 40.9% were female, mean LOS was 11.6 days, and inpatient mortality was 4.5%. Stroke rate was lower in AF hospitalizations (1.8% vs 2.1%, p<0.001). Mortality was lower in the AF (3.9%) versus the non-AF (5%) group (exact-matched OR or emOR=0.48, 95% CI 0.29 to 0.80, p<0.001; 987 matched pairs, n=2423), with similar results after procedural stratification: isolated valve replacement/repair (emOR=0.38, p<0.001), isolated coronary artery bypass graft (CABG) (emOR=0.33, p<0.001), and CABG with valve replacement/repair (emOR=0.55, p<0.001). A 12% increase was seen in LOS in the AF subgroup (exact-matched time ratio=1.12, 95% CI 1.10 to 1.14, p<0.001) among hospitalizations which underwent valve replacement/repair with or without CABG. Hospitalizations for cardiac surgery which had coexistent AF were found to have lower inpatient mortality risk and stroke prevalence but higher LOS and hospitalization costs compared with hospitalizations without AF.