Severe Infection Risk Exceptionally High in Schizophrenia

Liam Davenport

April 06, 2017

FLORENCE, Italy — For schizophrenia patients, rates of severe infection are much higher than in the general population. The findings underscore the need for infection prevention guidance in this highly vulnerable population.

In an analysis that included data on almost 900,000 individuals, rates of severe infection, including HIV, sepsis, hepatitis, skin infections, and tuberculosis, were significantly higher among schizophrenia patients.

"We should be aware that patients with schizophrenia are at high risk for severe infection and take steps to try and prevent these diseases," lead researcher Monika Pankiewicz-Dulacz, MD, University of Southern Denmark, Institute of Regional Health Services Research, Odense, told Medscape Medical News.

The study was presented here at the European Psychiatric Association (EPA) 2017 Congress.

Guidelines Needed

Although infections are known to contribute to the increased overall premature mortality in patients with schizophrenia, there is little information about the burden, pattern of occurrence, and types of severe infections in these patients.

"General guidelines and suggestions regarding prevention of severe infections among schizophrenia patients are needed, and they should address a wide range of areas, including hygiene, diet, activities, medications, treatment of comorbid conditions, and vaccinations," the investigators noted in a release.

To determine incidence rates of infections among young adults with schizophrenia and to define infection risk factors, the investigators used data from nationwide registers in Denmark on 893,647 individuals born between 1975 and 1990. Of these individuals, 7852 were diagnosed with schizophrenia between 1993 and 2013.

The investigators used Poisson regression to examine associations of different risk factors, including age, sex, substance abuse, and medical comorbidity, to estimate incidence rates of infections requiring hospitalization. The investigators also adjusted for comorbid conditions, including obesity, substance, and alcohol abuse.

Patients who died during the study period were were not included in the analysis; only the rates of infection during the patients' lifespans were calculated.

In both males and females, schizophrenia was associated with a significantly increased incidence rate of severe infections per person-year for each of the 5 years before and after schizophrenia diagnosis compared with the background population (P < .001).

Overall, 36% of schizophrenia patients had infectious diseases compared with 25% of background population. Schizophrenia patients were 63% more likely to suffer a serious infection.

The team found that rates of infections for HIV (0.23% vs 0.05%), sepsis (0.72% vs 0.27%), hepatitis (1.4% vs 0.22%), skin infections (12% vs 6.2%), and tuberculosis (0.12% vs 0.06%) were markedly higher among schizophrenia patients, with adjusted rates more than double in many cases.

The infection rate was also higher in males than in females, both among schizophrenia patients and in the background population.

The presence of comorbidities was associated with dramatic increases in the infection rate in both the background population and schizophrenia patients, with a 2.5-fold increase in infection risk in both groups and among males and females.

When the analysis was restricted to individuals with comorbidities, the infection rate in the background population was higher than the infection rate in schizophrenia patients without comorbidities.

Dr Pankiewicz-Dulacz said that a number of mechanisms may explain these findings.

It is well known that poor lifestyle choices increase infection risk. In addition, previous research has shown that individuals with schizophrenia "have abnormal immune patterns," including increased levels C-reactive protein. It is also possible that infection is a risk factor for psychosis, she said.

Infection Often Underestimated

Commenting on the findings for Medscape Medical News, István Bitter, MD, PhD, Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary, who moderated the poster session where the research was presented, said the study has several strengths, including its large sample size.

He noted that Dr Pankiewicz-Dulacz and colleagues tackled the "very important" clinical problem of increased premature mortality in schizophrenia. Although schizophrenia is not a cause of death, there is nevertheless a "high correlation" between premature death and schizophrenia, he said.

This research, said Dr Bitter, opens the door to further research into the potential causes of this undue risk for severe infection in patients with schizophrenia.

He added that infection risk and its potential impact are underestimated in most developed countries.

No funding for the study or relevant financial relationships have been disclosed.

European Psychiatric Association (EPA) 2017 Congress. Poster EW0605, presented April 4, 2017.

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