BACKGROUND : Schizoaffective disorder, bipolar type (SAD) and bipolar disorder I (BD) present a large clinical overlap. In a 1-year follow-up, we aimed to evaluate days to hospitalization (DTH) and predictors of relapse in a SAD-BD cohort of patients. METHODS : A 1-year, prospective, naturalistic cohort study considering DTH as primary outcome and incidence of direct and indirect measures of psychopathological compensation as secondary outcomes. Kaplan-Meyer survival analysis with Log-rank Mantel-Cox test compared BD/SAD subgroups as to DTH. After bivariate analyses, Cox regression was performed to assess covariates possibly associated with DTH in diagnostic subgroups. RESULTS : Of 836 screened patients, 437 were finally included (SAD = 105; BD = 332). Relapse rates in the SAD sample was n = 26 (24.8%) vs. n = 41 (12.3%) in the BD sample (p = 0.002). Mean ± SD DTH were 312.16 ± 10.6 (SAD) vs. 337.62 ± 4.4 (BD) days (p = 0.002). Patients with relapses showed more frequent suicide acts, violent behaviors, and changes in pharmacological treatments (all p < 0.0005) in comparison to patients without relapse. Patients without relapses had significantly higher mean number of treatments at T0 (p = 0.010). Cox regression model relating the association between diagnosis and DTH revealed that BD had higher rates of suicide attempts (HR = 13.0, 95%CI = 4.0-42.0, p < 0.0005), whereas SAD had higher rates of violent behavior during psychotic episodes (HR = 12.0, 95%CI = .3.3-43.5, p > 0.0005). CONCLUSIONS : SAD patients relapse earlier with higher hospitalization rates and violent behavior during psychotic episodes whereas bipolar patients have more suicide attempts. Psychiatric/psychological follow-up visits may delay hospitalizations by closely monitoring symptoms of self- and hetero-aggression.