Journal Article Annotations
2018, 4th Quarter
Annotations by Aum A. Pathare, MD
Type of study: Population-based cohort study
The finding: When compared with controls, patients with schizophrenia had a greater frequency of almost all types of infections. Comorbidity, defined in the paper as a wide range of conditions, ranging from myocardial infarction to substance use, was a major risk for both the schizophrenia and control group, and increased the susceptibility to infections by 176%. No single infection appeared to solely correlate to this risk over time, but after adjusting for comorbidity, the four groups with the highest positive association to schizophrenia were urological, genital, and skin infections, along with tuberculosis. However, the study failed to find any difference in the risk of infection during the premorbid phase of schizophrenia and the period after it was formally diagnosed.
Strength and weaknesses: This study is based on a national birth cohort, and utilizes population-based health registers, which minimize selection bias and improve generalizability. This has also enabled the investigators to account for a wide range of comorbidities, which appear to significantly influence the rate of infections. Limitations include lack of measurements for lifestyle, education, cognition, functional status, and smoking, factors which are known to increase the risk of infection. Disparities between how the two groups utilize healthcare could not be addressed. As patients with schizophrenia tend to eschew contact with healthcare providers, there is a potential for underestimating their medical problems.
Relevance: Based on this study, there appears to be a greater risk of infections in patients with schizophrenia, which is amplified by the presence of other medical comorbidities. Other studies have shown correlation between exposure to antipsychotics and pneumonia, as well as noting that infectious diseases are among the leading causes of mortality in this population. C-L psychiatrists, especially in integrated care settings, can participate in initiatives for prevention of infection, and changing the lifestyle factors associated with increased risk. Awareness of the excess risk of infection in patients with schizophrenia who receive medical care is essential, as the common infections may pass undetected. However, this study also highlights the bi-directionality of the association between psychiatric illness and infection, demonstrating that a causal relationship has not been established.