IJCS | Volume 33, Nº2, March / April 2020

181 Sarteschi et al. Predictors of post-discharge 30-day readmission Int J Cardiovasc Sci. 2020; 33(2):175-184 Original Article the wide reliability interval, this estimate could be considered as relatively early, however, this estimate is consistently present in other studies of this literature as well. A study developed in Boston in 2014 demonstrated that patients with low sodium levels presented an odds ratio of 1.45 on readmission within 30 days. 15 In a meta-analysis of observational studies, developed by Saito in 2015, including 57 articles, the importance of hyponatremia as a marker of bad prognosis of HF was also attested. 19 Corroborating previous studies, reduced left ventricle ejection fraction (LVEF) was an independent risk predictor of readmissions. 19-20 In the American study, it was demonstrated that LVEF < 45% had a direct associationwith hospital readmission due to other causes, with a risk of 1.25. 21 Data suggested that acute coronary syndrome (ACS) as a cause of decompensation is a relevant risk factor associated with readmission within 30 days of discharge. Unlike other precipitating factors of HF decompensation, such as excessive salt intake infections, lack of commitment to the treatment, among others, ACS cannot be prevented. Heart attack survivors have consistent risk of developing HF. Lower risk of HF can be related to decrease of comorbidities and/or evidence- based treatment. The possibility that the newheart injury secondary to the new acute coronary finding impacts an outcome of early hospital readmission is suggested here. 22 From this standpoint, patients with that condition can only be identified and from that, amore intensive strategy can be created at the post-discharge service. In this study, 49% of patients declared having diabetes as a comorbidity. Of these, 25% returned within 30 days of discharge, whereas, among non-diabetics, this percentage was 21%, not showing evidence that that factor is a possible risk factor of early readmission. Nevertheless, an analysis of more than 600 individuals identified type II DM as an independent predictor of readmission, as in Huynh’s study of 2015, in which DM was classified as a moderate criterion in models of short- term prediction. 19,23–24 The variables of gender and age were not predictors of hospital readmission. Regarding social factors, there is great controversy if those are or not predictors of HF prognosis. Some studies demonstrated the correlation of those variables with clinical outcomes, such as death and readmissions. 15 Paradoxically, a study conducted at a hospital in Tasmania tested twomodels of rehospitalization prediction: one including clinical data and another with non-clinical data such as gender, age, whether the person lives alone, and so on. The author demonstrated that the model with clinical data reported a better discriminatory power for hospital readmission. 25 High levels of creatinine and urea are associated with worse in-hospital survival and outcome after discharge. 15,26 The risk score ADHERE — a globally accepted score for the prediction of in-hospital mortality due to HF — takes in consideration only those two markers, in addition to systolic blood pressure. 9 Nevertheless, in this study, although creatinine and urea levels are biologically plausible, they did not present any relevant association with readmissions, possibly due to no statistical power detected in such correlations. As in the HF spectrum, in systolic blood pressure on admission, there was no confirmed association with readmission. In this study, betablockers (BB), as well as the association of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB), were prescribed during hospitalization to the majority of the patients (77%), a much higher number than the ones announced by the BREATHE registry, which were 57% of BB, 42% of ACEI and 24% of ARB. Considering HF patients, with reduced LVEF, the indication was higher: 82% in the case of ACEI/ARB and 84% for betablockers. These findings highlight the practice of the studied center in following the recommended standards, in line with the guidelines from several countries, as well as the Brazilian Guideline for Chronic HF, in which there is a consensus on the therapeutic use of BB drugs related to ACEI and ARB, their well-established clinical benefits on death caused by HF, besides the improvement of symptoms and reduction of readmission due to HF. 4,27- 29 Nevertheless, in our specific population, the use of those medications during hospitalization was not confirmed as a protection factor against readmissions in the short-run. This might be explained by the fact that commitment and continuous use of therapeutic are largely associated with patient evolution than with its prescription during hospitalization. The biochemical marker troponin as well as B-type natriuretic peptide (NT-proBNP) were validated in previous studies as relevant predictors of readmissions, however in this study, they were not analyzed due to the limited number of patients with those information from exams, as in our Brazilian reality, both troponin and NT- proBNP are not requested from all patients. 30