IJCS | Volume 33, Nº2, March / April 2020

180 Figure 2 – Multivariable model for 30-Days readmission – Odds Ratio (95%CI). ACS: acute coronary syndrome; LVEF: left ventricular ejection fraction. Sarteschi et al. Predictors of post-discharge 30-day readmission Int J Cardiovasc Sci. 2020; 33(2):175-184 Original Article BRL 920 in 2008 to BRL 1,559 in 2016. 13-14 A possible explanation to the increased length of stay may be due to the fact that the study was conducted at a private hospital, where there is no major issues of scarcity of hospital beds, hence less pressure from the public health system for early patient discharge. In this study, the readmission rate of patients with DHF within 30 days of discharge was 23%, which is consistent with other published studies, in which 24% of the participants were readmitted within 30 days. 15-17 Historically, several measurements have been proposed in order to create models of HF prognostic prediction; however, those models have presented limited predictive capabilities, as we are dealing with a chronic disease whose outcome is associated with multiple causes, including the form of presentation and severity of the disease, clinical and behavioral characteristics of the patients, in addition to factors such as failure of the health system, which is not comparable to models from developed countries. In a systematic review of 30 studies that developed models of hospital readmission prediction, the C-statistic varied from 0.55 to 0.65, demonstrating the inexistence of predictor scores of high discriminatory power. 18 Among 26 analyzed variables of hospital readmission within 30 days of discharge, using the multivariable logistic model, this study identified the following factors as predictors of independent risk: LVEF < 40%, hyponatremia andACS as causes of decompensation. The final logisticmodel presented a reasonable discriminatory power (C-statistic = 0.655 – 95%CI 0.582 – 0.728) and good calibration (Hosmer-Lemeshow: χ 2 = 0.892, p = 0.925). It was demonstrated that patients with hyponatremia at the time of hospital admission had three times more chance of readmission (95%CI 1.01 – 11.19) in comparison with those with normal sodium levels. Notwithstanding