The incidence and all-cause mortality of pneumonia in patients with schizophrenia: A nine-year follow-up study

Objective: This study sought to estimate the incidence, all-cause mortality and relative risks for patients with schizophrenia after a pneumonia diagnosis. Methods: The population was identified from the Taiwanese National Health Insurance Research Database (NHIRD) in 1999 and included 59,021 patients with schizophrenia and 236,084 age- and sex-matched control participants without schizophrenia. These participants were randomly selected from the 23,981,020-participant NHIRD, which contain 96% of the entire population. Using the 2000-2008 NIHRD, the incidence and nine-year pneumonia-free survival rate of pneumonia (ICD-9-CM codes 486 and 507.0-507.8) were calculated. Results: Over nine years, 6055 (10.26%) patients with schizophrenia and 7844 (332%) controls had pneumonia. The pneumonia incidence density was 11.4/1000 person-years among the patients with schizophrenia, who experienced a 3.09-fold increased risk of developing pneumonia. After adjusting for other covariates, the patients with schizophrenia still experienced a 1.77-fold increased risk of developing pneumonia. Although, without adjustment, fewer schizophrenia patients than controls died after having pneumonia (2121 [35.12%] vs. 3497 [44.62%]), after adjusting for other variables, the mortality hazard ratio for patients with schizophrenia was 1.39. Conclusions: During a nine-year follow-up, the likelihood of developing pneumonia and all-cause mortality among patients with schizophrenia was higher than that of the non-schizophrenia group as was the mortality rate. Interestingly, the psychiatric proportion of days covered (PDC) was positively associated with pneumonia (OR: 2.51) but negatively associated with death (HR: 0.72). These findings imply the importance of iatrogenic factors and psychotropic drugs (including their benefits and side effects) and highlight the directions for future studies. (C) 2012 Elsevier Ltd. All rights reserved.