Journal Article Annotations
2018, 4th Quarter

Infectious Diseases

Annotations by Aum A. Pathare, MD
January 2019

Incidence rates and risk of hospital registered infections among schizophrenia patients before and after onset of illness: a population-based nationwide register study

PUBLICATION #1 — Infectious Diseases

Incidence rates and risk of hospital registered infections among schizophrenia patients before and after onset of illness: a population-based nationwide register study

Pankiewicz-Dulacz M, Stenager E, Chen M, Stenager E

Abstract: J Clin Med 2018; 7(12):485

Infections in schizophrenia patients are associated with an increased premature mortality. However, our knowledge about the burden of infections in schizophrenia is scarce. The aims of this study were to (1) determine the prevalence of clinically important hospital registered infections in the period of five years prior to and five years after the diagnosis, (2) estimate the risk of infections before and after the schizophrenia diagnosis and, (3) evaluate the impact of comorbidity on the risk of infections in schizophrenia. Using combined data from Danish national registers, we sampled a cohort of all persons born in Denmark in the period 1975⁻1990 and obtained health-related records from 1995⁻2013. Occurrence patterns and the risk of infections were measured as annual incidence rates and incidence rates ratios, estimated using Poisson models. Medical conditions from the Charlson Index were considered as a measure of comorbidity. The analyses showed that schizophrenia patients had a significantly elevated risk of almost all types of hospital registered infections during the period of the study when compared to the controls. Comorbidity increased rates of infections by 176%. The results suggest that the risk of infections is elevated in the schizophrenia population and physical illness is an important risk factor.

On PubMed: J Clin Med 2018; 7(12):485

Annotation

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.