Individuals with severe mental disorders (SMDs) such as psychotic disorders, bipolar disorders, and single manic episodes have increased mortality associated with COVID-19 infection. We set up a population-based study to examine whether individuals with SMD also had a higher risk of hospitalization and death from other infectious conditions. Anonymized and summarized data from multiple Swedish patient registers covering the entire Swedish population were supplied by the Swedish National Board of Health and Welfare. The frequencies of hospitalizations and deaths associated with influenza/pneumonia and sepsis in individuals with SMD were compared with the rest of the population during 2018–2019. Possible contributing comorbidities were also examined, of which diabetes, cardiovascular disease, chronic lung disease, and hypertension were chosen. A total of 7,780,727 individuals were included in the study; 97,034 (1.2%) cases with SMD and 7,683,693 (98.8%) controls. Individuals with SMD had increased risk of death associated with influenza/pneumonia (OR = 2.06, 95% CI [1.87–2.27]) and sepsis (OR = 1.61, 95% CI [1.38–1.89]). They also had an increased risk of hospitalization associated with influenza/pneumonia (OR = 2.12, 95% CI [2.03–2.20]) and sepsis (OR = 1.89, 95% CI [1.75–2.03]). Our results identify a need for further evaluation of whether these individuals should be included in prioritized risk groups for vaccination against infectious diseases other than COVID-19.

The prescription of thyroid hormone replacement therapy (THRT) has increased in the general population; the thyroid stimulating hormone (TSH) threshold to initiate THRT has decreased. It remains unclear whether a similar trend has occurred in patients with bipolar disorder (BD). In this work we explore patterns and trends of prescribing THRT in patients with BD or schizoaffective disorder (SZD) with an observational study and time-trend analysis in the framework of the LiSIE (Lithium—Study into Effects and Side Effects) retrospective cohort study. In most patients, THRT was initiated for subclinical hypothyroidism. The median TSH at which THRT was started was 6.0 (IQR 4.0) mIU/L and the median free serum thyroxine (fT4) at which THRT was started was 11.8 (IQR 3.9) pmol/L. The median TSH concentration at the start of THRT decreased annually with 0.10 mIU/L (p = 0.047) and was higher in patients treated with lithium than in patients treated with other mood stabilisers (p = 0.02). In conclusion, THRT was typically initiated in the context of mild or absent alterations of thyroid function tests with a decreasing TSH threshold. As THRT is rarely reversed once initiated, clinicians need to weigh up potential benefits and risks when prescribing THRT for subclinical hypothyroidism in patients with BD or SZD.

Previous research has suggested antiviral properties for lithium, including potential effectiveness against COVID-19 in vitro. This study aimed to investigate the impact of lithium and other psychotropic drugs on the risks of mortality, hospitalization, and ICU admission due to COVID-19 among individuals with bipolar disorder. The primary objective was to assess whether lithium was beneficial in COVID-19-infection in a real-world population. Retrospective register study using data from multiple Swedish patient registers, including 39,063 individuals in Sweden with bipolar disorder and prescribed mood stabilizers. Outcomes included COVID-19-associated death, hospitalization, and ICU admission between 11 March 2020 and 10 March 2021. Multivariate logistic regression adjusted for age, sex, and somatic comorbidities was conducted. Lithium were prescribed to 44.2 % of patients, either as mono- or combination therapy; other mood stabilizers were prescribed to 55.8 %. There were no significant associations between lithium and COVID-19-associated death, hospitalization, or ICU admission. Atypical antipsychotics were associated with increased odds ratios for COVID-19-associated death (OR 1.58 [95 % CI 1.01-2.47]), hospitalization (OR 1.80 [95 % CI 1.49-2.18]), and ICU admission (OR 2.25 [95 % CI 1.33-3.80]). Benzodiazepines were associated with a significant increase in COVID-19-associated death (OR 1.54 [95 % CI 1.01-2.35]) and hospitalization OR 1.26 [95 % CI 1.03-1.53]). In an ad hoc analysis, lithium monotherapy was, however, associated with reduced hospitalizations and ICU admissions. Our findings weaken the hypothesis that lithium reduces the risk of severe events associated with COVID-19 infection in bipolar disorder.