Incidence Rates and Risk of Hospital Registered Infections among Schizophrenia Patients before and after Onset of Illness: A Population-Based Nationwide Register Study

Antipsychotic medications and severe sepsis in schizophrenia: A nested case-control study

BACKGROUND

Sepsis constitutes a condition that involves life-threatening organ dysfunction induced by severe infection. This nested case-control study investigated risk factors for severe sepsis and whether antipsychotic use is associated with severe sepsis risk in patients with schizophrenia, a topic that has not been comprehensively explored in previous studies.

METHODS

We selected 39,432 patients with schizophrenia aged between 15 and 65 years from Taiwan's Psychiatric Inpatient Medical Claims database for the period 2000-2012. The case group comprised patients with severe sepsis after their first psychiatric admission (n = 1382). The case and control groups were randomly matched (1:4) by age, sex and first psychiatric admission (year) and finally comprised 1382 and 5528 individuals, respectively. We employed multivariable conditional logistic regression to identify (1) risk factors (physical illnesses and nonpsychiatric medications) and (2) antipsychotic-severe sepsis associations.

RESULTS

Higher numbers of psychiatric admissions and physical illnesses such as delirium, cerebrovascular disease and cancer were significantly associated with a higher risk of severe sepsis. Furthermore, severe sepsis was associated with the use of antithrombotic agents, systemic corticosteroids and agents targeting the renin-angiotensin system. Clozapine (adjusted risk ratio = 1.65) and quetiapine (adjusted risk ratio = 1.59) use were associated with an increased risk of severe sepsis. The use of more than one antipsychotic drug could further increase this risk.

CONCLUSION

Several physical illnesses and nonpsychiatric medications increase the risk of severe sepsis in patients with schizophrenia. Specifically, clozapine or quetiapine use significantly increased the risk of severe sepsis in these patients.

Bidirectional two-sample Mendelian randomization study of differential white blood cell counts and schizophrenia

BACKGROUND

Schizophrenia and white blood cell counts (WBC) are both complex and polygenic traits. Previous evidence suggests that increased WBC are associated with higher all-cause mortality, and other studies have found elevated WBC in first-episode psychosis and chronic schizophrenia. However, these observational findings may be confounded by antipsychotic exposures and their effects on WBC. Mendelian randomization (MR) is a useful method for examining the directions of genetically-predicted relationships between schizophrenia and WBC.

METHODS

We performed a two-sample MR using summary statistics from genome-wide association studies (GWAS) conducted by the Psychiatric Genomics Consortium Schizophrenia Workgroup (N = 130,644) and the Blood Cell Consortium (N = 563,946). The MR methods included inverse variance weighted (IVW), MR Egger, weighted median, MR-PRESSO, contamination mixture, and a novel approach called mixture model reciprocal causal inference (MRCI). False discovery rate was employed to correct for multiple testing.

RESULTS

Multiple MR methods supported bidirectional genetically-predicted relationships between lymphocyte count and schizophrenia: IVW (b = 0.026; FDR p-value = 0.008), MR Egger (b = 0.026; FDR p-value = 0.008), weighted median (b = 0.013; FDR p-value = 0.049), and MR-PRESSO (b = 0.014; FDR p-value = 0.010) in the forward direction, and IVW (OR = 1.100; FDR p-value = 0.021), MR Egger (OR = 1.231; FDR p-value < 0.001), weighted median (OR = 1.136; FDR p-value = 0.006) and MRCI (OR = 1.260; FDR p-value = 0.026) in the reverse direction. MR Egger (OR = 1.171; FDR p-value < 0.001) and MRCI (OR = 1.154; FDR p-value = 0.026) both suggested genetically-predicted eosinophil count is associated with schizophrenia, but MR Egger (b = 0.060; FDR p-value = 0.010) and contamination mixture (b = -0.013; FDR p-value = 0.045) gave ambiguous results on whether genetically predicted liability to schizophrenia would be associated with eosinophil count. MR Egger (b = 0.044; FDR p-value = 0.010) and MR-PRESSO (b = 0.009; FDR p-value = 0.045) supported genetically predicted liability to schizophrenia is associated with elevated monocyte count, and the opposite direction was also indicated by MR Egger (OR = 1.231; FDR p-value = 0.045). Lastly, unidirectional genetic liability from schizophrenia to neutrophil count were proposed by MR-PRESSO (b = 0.011; FDR p-value = 0.028) and contamination mixture (b = 0.011; FDR p-value = 0.045) method.

CONCLUSION

This MR study utilised multiple MR methods to obtain results suggesting bidirectional genetic genetically-predicted relationships for elevated lymphocyte counts and schizophrenia risk. In addition, moderate evidence also showed bidirectional genetically-predicted relationships between schizophrenia and monocyte counts, and unidirectional effect from genetic liability for eosinophil count to schizophrenia and from genetic liability for schizophrenia to neutrophil count. The influence of schizophrenia to eosinophil count is less certain. Our findings support the role of WBC in schizophrenia and concur with the hypothesis of neuroinflammation in schizophrenia.

A Sex-Dependent Association Between Doxycycline Use and Development of Schizophrenia

BACKGROUND

Doxycycline and minocycline are brain-penetrant tetracycline antibiotics, which recently gained interest because of their immunomodulatory and neuroprotective properties. Observational studies have suggested that exposure to these drugs may decrease the risk to develop schizophrenia, but results are inconsistent. The aim of this study was to investigate the potential association between doxycycline use and later onset of schizophrenia.

DESIGN

We used data from 1 647 298 individuals born between 1980 and 2006 available through Danish population registers. 79 078 of those individuals were exposed to doxycycline, defined as redemption of at least 1 prescription. Survival analysis models stratified for sex with time-varying covariates were constructed to assess incidence rate ratios (IRRs) for schizophrenia (ICD-10 code F20.xx), with adjustment for age, calendar year, parental psychiatric status, and educational level.

RESULTS

In the non-stratified analysis, there was no association between doxycycline exposure and schizophrenia risk. However, men who redeemed doxycycline had a significantly lower incidence rate for schizophrenia onset compared to men that did not (IRR 0.70; 95% CI 0.57-0.86). By contrast, women had a significantly higher incidence rate for schizophrenia onset, compared to women that did not redeem doxycycline prescriptions (IRR 1.23; 95% CI 1.08, 1.40). The effects were not found for other tetracycline antibiotics (IRR 1.00; 95% CI 0.91, 1.09).

CONCLUSIONS

Doxycycline exposure is associated with a sex-dependent effect on schizophrenia risk. The next steps are replication of the results in independent well-characterized population cohorts, as well as preclinical studies to investigate sex-specific effects of doxycycline on biological mechanisms implicated in schizophrenia.

ERS/ESTS statement on the management of pleural infection in adults

Pleural infection is a common condition encountered by respiratory physicians and thoracic surgeons alike. The European Respiratory Society (ERS) and European Society of Thoracic Surgeons (ESTS) established a multidisciplinary collaboration of clinicians with expertise in managing pleural infection with the aim of producing a comprehensive review of the scientific literature. Six areas of interest were identified: 1) epidemiology of pleural infection, 2) optimal antibiotic strategy, 3) diagnostic parameters for chest tube drainage, 4) status of intrapleural therapies, 5) role of surgery and 6) current place of outcome prediction in management. The literature revealed that recently updated epidemiological data continue to show an overall upwards trend in incidence, but there is an urgent need for a more comprehensive characterisation of the burden of pleural infection in specific populations such as immunocompromised hosts. There is a sparsity of regular analyses and documentation of microbiological patterns at a local level to inform geographical variation, and ongoing research efforts are needed to improve antibiotic stewardship. The evidence remains in favour of a small-bore chest tube optimally placed under image guidance as an appropriate initial intervention for most cases of pleural infection. With a growing body of data suggesting delays to treatment are key contributors to poor outcomes, this suggests that earlier consideration of combination intrapleural enzyme therapy (IET) with concurrent surgical consultation should remain a priority. Since publication of the MIST-2 study, there has been considerable data supporting safety and efficacy of IET, but further studies are needed to optimise dosing using individualised biomarkers of treatment failure. Pending further prospective evaluation, the MIST-2 regimen remains the most evidence based. Several studies have externally validated the RAPID score, but it requires incorporating into prospective intervention studies prior to adopting into clinical practice.

Limited association between infections, autoimmune disease and genetic risk and immune activation in severe mental disorders

BACKGROUND

Low-grade inflammation may be part of the underlying mechanism of schizophrenia and bipolar disorder. We investigated if genetic susceptibility, infections or autoimmunity could explain the immune activation.

METHODS

Seven immune markers were selected based on indicated associations to severe mental disorders (IL-1Ra, sIL-2R, IL-18, sgp130, sTNFR-1, APRIL, ICAM-1) and measured in plasma of patients with schizophrenia (SCZ, N = 732) and bipolar spectrum disorders (BD, N = 460) and healthy controls (HC, N = 938). Information on rate of infections and autoimmune diseases were obtained from Norwegian national health registries for a twelve-year period. Polygenic risk scores (PRS) of SCZ and BD were calculated from genome-wide association studies. Analysis of covariance were used to test effects of infection rate, autoimmune disease and PRS on differences in immune markers between patients and HC.

RESULTS

Infection rate differed between all groups (BD > HC > SCZ, all p < 0.001) whereas autoimmune disease was more frequent in BD compared to SCZ (p = 0.004) and HC (p = 0.003). sIL-2R was positively associated with autoimmune disease (p = 0.001) and negatively associated with PRS of SCZ (p = 0.006) across SCZ and HC; however, associations represented only small changes in the difference of sIL-2R levels between SCZ and HC.

CONCLUSION

There were few significant associations between rate of infections, autoimmune disease or PRS and altered immune markers in SCZ and BD, and the detected associations represented only small changes in the immune aberrations. The findings suggest that most of the low-grade inflammation in SCZ and BD is explained by other factors than the underlying PRS, autoimmunity and infection rates.

The Atypical Antipsychotic Quetiapine Promotes Multiple Antibiotic Resistance in Escherichia coli

Atypical antipsychotic (AAP) medication is a critical tool for treating symptoms of psychiatric disorders. While AAPs primarily target dopamine (D2) and serotonin (5HT2A and 5HT1A) receptors, they also exhibit intrinsic antimicrobial activity as an off-target effect. Because AAPs are often prescribed to patients for many years, a potential risk associated with long-term AAP use is the unintended emergence of bacteria with antimicrobial resistance (AMR). Here, we show that exposure to the AAP quetiapine at estimated gut concentrations promotes AMR in Escherichia coli after 6 weeks. Quetiapine-exposed isolates exhibited an increase in MICs for ampicillin, tetracycline, ceftriaxone, and levofloxacin. By whole-genome sequencing analysis, we identified mutations in genes that confer AMR, including the repressor for the multiple antibiotic resistance mar operon (marR), and real-time reverse transcription-quantitative PCR (RT-qPCR) analysis showed increased levels of marA, acrA, and tolC mRNAs and reduced levels of ompF mRNA in the isolates carrying marR mutations. To determine the contribution of each marR mutation to AMR, we constructed isogenic strains carrying individual mutant marR alleles in the parent background and reevaluated their resistance phenotypes using MIC and RT-qPCR assays. While marR mutations induced robust activity of the mar operon, they resulted in only modest increases in MICs. Interestingly, although these marR mutations did not fully recapitulate the AMR phenotype of the quetiapine-exposed isolates, we show that marR mutations promote growth fitness in the presence of quetiapine. Our findings revealed an important link between the use of AAPs and AMR development in E. coli. IMPORTANCE AAP medication is a cornerstone in the treatment of serious psychiatric disease. The AAPs are known to exhibit antimicrobial activity; therefore, a potential unintended risk of long-term AAP use may be the emergence of AMR, although such risk has received little attention. In this study, we describe the development of multidrug antibiotic resistance in Escherichia coli after 6 weeks of exposure to the AAP quetiapine. Investigation of mutations in the marR gene, which encodes a repressor for the multiple antibiotic resistance (mar) operon, reveals a potential mechanism that increases the fitness of E. coli in the presence of quetiapine. Our findings establish a link between the use of AAPs and AMR development in bacteria.

Increased rates of respiratory disease in schizophrenia: A systematic review and meta-analysis including 619,214 individuals with schizophrenia and 52,159,551 controls

INTRODUCTION

Despite respiratory disease being a major cause of excess mortality in people with schizophrenia, the prevalence of respiratory conditions in this population is poorly defined. A systematic review and meta-analysis were conducted to establish the prevalence and association of respiratory diseases in people with schizophrenia.

MATERIAL AND METHODS

Major electronic databases were searched from inception to 27 April 2020 for articles reporting respiratory disease (asthma, chronic obstructive pulmonary disease [COPD], pneumonia, and tuberculosis) in people with schizophrenia and, where possible, a control group. A random-effects meta-analysis was conducted. The study was registered with PROSPERO (CRD42018115137).

RESULTS

Of 1569 citations, 21 studies consisting of 619,214 individuals with schizophrenia and 52,159,551 controls were included in the meta-analysis. Compared to the general population, people with schizophrenia had significantly higher rates of COPD (odds ratio [OR]: 1.82, 95% CI: 1.28-2.57), asthma (OR: 1.70, 95% CI: 1.02-2.83), and pneumonia (OR: 2.62, 95% CI: 1.10-6.23). In people with schizophrenia, the prevalence of COPD was 7.7% (95% CI: 4.0-14.4), asthma 7.5% (95% CI: 4.9-11.3), pneumonia 10.3% (95% CI 5.4-18.6), and tuberculosis 0.3% (95% CI 0.1 -0.8). After adjusting for publication bias, the prevalence of COPD increased to 19.9% (95% CI: 9.6-36.7).

DISCUSSION

All respiratory diseases examined were significantly more prevalent in people with schizophrenia compared with the general population. Future studies should focus on improving the prevention and management of respiratory disease in this group to reduce associated excess mortality.

Pneumonia: host susceptibility and shared genetics with pulmonary function and other traits

Pneumonia is a common and severe infectious lung disease. Host genetics, together with underlying medical and lifestyle conditions, determine pneumonia susceptibility. We performed a secondary analysis of the results of two genome-wide studies for pneumonia in 23andMe participants (40 600 cases/90 039 controls) (Tian et al., 2017) and UK Biobank (BB) participants (12 614 cases/324 585 controls) (via the Global Biobank Engine) and used the GTEx database to correlate the results with expression quantitative trait loci (eQTLs) data in lung and whole blood. In the 23andMe pneumonia single nucleotide polymorphism (SNP) set, 177 genotyped SNPs in the human leukocyte antigen (HLA) region satisfied the genome-wide significance level, P ≤ 5·0E-08. Several target genes (e.g. C4A, VARS2, SFTA2, HLA-C, HLA-DQA2) were unidirectionally regulated by many HLA eSNPs associated with a higher risk of pneumonia. In lung, C4A transcript was up-regulated by 291 pneumonia risk alleles spanning the half the HLA region. Among SNPs correlated with the expression levels of SFTA2 and VARS2, approximately 75% overlapped: all risk alleles were associated with VARS2 up-regulation and SFTA2 down-regulation. To find shared gene loci between pneumonia and pulmonary function (PF), we used data from the Global Biobank Engine and literature on genome-wide association studies (GWAS) of PF in general populations. Numerous gene loci overlapped between pneumonia and PF: 28·8% in the BB data set and 49·2% in the 23andMe data set. Enrichment analysis within the database of Genotypes and Phenotypes (dbGaP) and National Human Genome Research Institute-European Bioinformatics Institute (NHGRI-EBI) Catalog of pneumonia and pneumonia/PF gene sets identified significant overlap between these gene sets and genes related to inflammatory, developmental, neuropsychiatric and cardiovascular and obesity-related traits.

Risk factors of major infections in schizophrenia. A nationwide Danish register study

BACKGROUND

Risk of infections is elevated in patients with schizophrenia. Predicting their occurrence is essential, as infections in this group of patients are associated with prolonged hospital admission and increased mortality. The objective of the current investigation was to identify the potential risk factors of major infection after diagnosis with schizophrenia.

METHODS

This national prospective observational cohort study included 7788 people with schizophrenia born in Denmark between 1975 and 1990. Socio-demographic, psychiatric and health related data were obtained from Danish national registers. The Cox regression model was used for data analyses. Crude and adjusted hazard ratios (HRs) with 95% confidence intervals (95%CIs) are presented.

RESULTS

The most significant risk factors associated with the development of major infections included young age, female gender, medical comorbidity and substance abuse. A history of treatment with antipsychotics preceding the diagnosis was negatively associated with such morbidity.

CONCLUSION

This study reports several factors that might increase the risk of infections in individuals with schizophrenia. Early intervention towards infections should be considered in the subpopulation of schizophrenia patients who are at increased risk of infections.