BackgroundA systematic review, including 203 studies, estimated that people with mental disorders have a mortality rate 2.2 times higher than the general population or control samples; the majority of these studies were conducted in developed countries. A possibility that underlies this excess mortality is that mental disorders increase the risk for communicable and non-communicable diseases and unintentional and intentional injuries. On the other hand, many health conditions increase the risk of mental disorders, and this comorbidity compromises the search for health care and may also impact survival estimates.We investigated the main causes of mortality in patients with mental disorders and the most prevalent psychiatric diagnoses involved, as well as the impact of communicable and non-communicable comorbidities on the survival estimates of these patients in a Brazilian cohort.MethodsWe evaluated 3,011 patients hospitalized due to mental disorders, over 18 years old, included in a web-based system of mental health information (SISAM-13). The SISAM-13 database is composed, in addition to sociodemographic data, of comorbidities such as hypertension, diabetes, infectious disease, trauma, respiratory problems, sequelae of cerebrovascular accident and epilepsy. This cohort was registered between April 2011 and November 2016. Information on mortality was conducted in collaboration with the SEADE, the center of São Paulo State Government in production of socioeconomic and health data, and December 2016 was the final point of the survival time. Diagnosis and mortality cause were coded according to ICD-10. The Kaplan-Meier method was used to estimate the survival function. Differences between groups were assessed with the log-rank test.ResultsIn total, 568 (26.2%) of valid cases presented comorbidities, and 124 patients (4.1%) died. The most prevalent causes of death were related to external causes (24.2%), and respiratory (17.7%), circulatory (11.3%) and digestive (8.1%) diseases. The presence of comorbidity decreased patients’ life expectancy: the median survival estimate for patients with comorbidities was 77.9 years (95% CI, 74.9 to 79.5 years), while for those without comorbidity was 80.8 years (95% CI, 78.9 to 83.2 years); X2(1) = 4.202; p = 0.040. The three most prevalent diagnoses were mental disorders due to substance use (40.7%), affective disorders (22.7%) and psychotic disorders (20.0%). The average survival estimate was lower among patients with substance use disorder (69.2 years; 95% CI, 66.4 to 72.0 years) compared to affective disorders (78.7 years; 95% CI, 76.6 to 80.8 years) and psychoses (80.3 years; 95% CI, 78.0 to 82.7 years); X2(2) = 30.807; p <0.001. No differences were observed in the interaction between the most prevalent diagnoses and presence of comorbidities.DiscussionThis study is the first of our knowledge to explore life estimates related to comorbidities and the most prevalent psychiatric diagnoses in patients living in a low- and middle-income country (LAMIC). In this sense, it was found that having comorbidity reduced life expectancy, independently of the psychiatric diagnosis; and among the most prevalent disorders, those related to psychoactive substance use presented the lowest life expectancy. These findings suggest the need for a comprehensive view of the psychiatric patient with comorbidities, as well as the urgency of public health policies directed at psychoactive substance users given the high prevalence and low life expectancy in this group of patients.