IJCS | Volume 33, Nº2, March / April 2020

177 Figure 1 - Flowchart of the sample selection process analyzed. Patients hospitalized with acute decompensated heart failure from 2008 to 2016 Hospitalizations: 372 patients Database monitored after admission: (n = 319) Sample analyzed: (n = 312) Excluded: 53 patients (death during hospitalization) Excluded: 7 patients (loss of follow-up) Sarteschi et al. Predictors of post-discharge 30-day readmission Int J Cardiovasc Sci. 2020; 33(2):175-184 Original Article standard deviation (SD) for quantitative variables and absolute and relative frequencies for qualitative variables. Bivariate analysis, by Pearson’s Chi-Square test, was conducted as a strategy to evaluate the correlation between outcome (readmission within 30 days) and the independent variables studied. In order to build a multivariable logistic regressionmodel, we considered all the variables which, in the bivariate analysis, presented an association with readmission with p < 0.20. The stepwise forward method was applied to select the final model. The selected variables had their interactions, if any, examined by correlation matrix, interactions with correlation coefficient greater or equal to 0.5 were included in the model. Once the final model was defined, model calibrationwas evaluated by the Hosmer- LemeshowGoodness-of-fit test. Discrimination capability of the final model was studied by the C-statistic, that is, the area under the curve built from the receiver operating characteristic curve. The program SPSS for Windows, version 21.0 – Statistical Package for Social Sciences (IBM, Armonk, NY) was used to do the statistics calculations. The level of significance assumed was 5%. The project was approved by the Research Ethics Committee of Centro de Pesquisas Aggeu Magalh es (CPqAM) of Fiocruz/PE, with CAAE registration number 67404216.8.0000.5190, in accordance with the Declaration of Helsinki. Results This study included 372 patients that met the criteria of inclusion and exclusion from 2008 to 2016. The analyzed sample of 312 patients was created according to Figure 1. Of those patients, 71 (22%) were readmitted within 30 days after hospital discharge. The age of the patients varied from 26 to 99 years of age, with mean 73 (SD = 14) years, with 232 (74%) patients aged 65 or older, the majority of men (62%), NYHA-Class III (50%), ischemic etiology (58%), LVEF ≥ 40% (57%) and hospital admission period over 1 week (64%). Among previous comorbidities, systemic arterial hypertension (SAH) was present in 86% of the patients, diabetes mellitus (DM) in 49%, severe kidney disease in 30% and chronic obstructive pulmonary disease (COPD)/asthma in 18%. The main cause of decompensation was acute coronary syndrome (ACS) (46%), followed by arrhythmia (25%) and infection (23%). Regarding drug therapy during hospitalization,