Transmembrane helix interactions regulate oligomerization of the receptor tyrosine kinase EphA2.

The transmembrane helices of receptor tyrosine kinases (RTKs) have been proposed to switch between two different dimeric conformations, one associated with the inactive RTK and the other with the active RTK. Furthermore, recent work has demonstrated that some full-length RTKs are associated into oligomers that are larger than dimers, raising questions about the roles of the TM helices in the assembly and function of these oligomers. Here we probe the roles of the TM helices in the assembly of EphA2 RTK oligomers in the plasma membrane. We employ mutagenesis to evaluate the relevance of a published NMR dimeric structure of the isolated EphA2 TM helix in the context of the full-length EphA2 in the plasma membrane. We use two fluorescence methods, Förster Resonance Energy Transfer and Fluorescence Intensity Fluctuations spectrometry, which yield complementary information about the EphA2 oligomerization process. These studies reveal that the TM helix mutations affect the stability, structure, and size of EphA2 oligomers. However, the effects are multifaceted and point to a more complex role of the TM helix than the one expected from the "TM dimer switch" model.

Utility of FRET in studies of membrane protein oligomerization: The concept of the effective dissociation constant.

The activity of many membrane receptors is controlled through their lateral association into dimers or higher-order oligomers. Although Förster resonance energy transfer (FRET) measurements have been used extensively to characterize the stability of receptor dimers, the utility of FRET in studies of larger oligomers has been limited. Here we introduce an effective equilibrium dissociation constant that can be extracted from FRET measurements for EphA2, a receptor tyrosine kinase (RTK) known to form active oligomers of heterogeneous distributions in response to its ligand ephrinA1-Fc. The newly introduced effective equilibrium dissociation constant has a well-defined physical meaning and biological significance. It denotes the receptor concentration for which half of the receptors are monomeric and inactive, and the other half are associated into oligomers and are active, irrespective of the exact oligomer size. This work introduces a new dimension to the utility of FRET in studies of membrane receptor association and signaling in the plasma membrane.

Burden of disease among patients with prevalent Crohn's disease: results from a large German sickness fund.

PURPOSE: The aim of this study was to investigate the burden of disease among a real-world cohort of patients with prevalent Crohn's disease (CD) in Germany. METHODS: We conducted a retrospective cohort analysis using administrative claims data from the German AOK PLUS health insurance fund. Continuously insured patients with a CD diagnosis between 01 October 2014 and 31 December 2018 were selected and followed for at least 12 months or longer until death or end of data availability on 31 December 2019. Medication use (biologics, immunosuppressants (IMS), steroids, 5-aminosalicylic acid) was assessed sequentially in the follow-up period. Among patients with no IMS or biologics (advanced therapy), we investigated indicators of active disease and corticosteroid use. RESULTS: Overall, 9284 prevalent CD patients were identified. Within the study period, 14.7% of CD patients were treated with biologics and 11.6% received IMS. Approximately 47% of all prevalent CD patients had mild disease, defined as no advanced therapy and signs of disease activity. Of 6836 (73.6%) patients who did not receive advanced therapy in the follow-up period, 36.3% showed signs of active disease; 40.1% used corticosteroids (including oral budesonide), with 9.9% exhibiting steroid dependency (≥ 1 prescription every 3 months for at least 12 months) in the available follow-up. CONCLUSIONS: This study suggests that there remains a large burden of disease among patients who do not receive IMS or biologics in the real world in Germany. A revision of treatment algorithms of patients in this setting according to the latest guidelines may improve patient outcomes.

Quantitative characterization of tetraspanin 8 homointeractions in the plasma membrane.

The spatial distribution of proteins in cell membranes is crucial for signal transduction, cell communication and membrane trafficking. Members of the Tetraspanin family organize functional protein clusters within the plasma membrane into so-called Tetraspanin-enriched microdomains (TEMs). Direct interactions between Tetraspanins are believed to be important for this organization. However, studies thus far have utilized mainly co-immunoprecipitation methods that cannot distinguish between direct and indirect, through common partners, interactions. Here we study Tetraspanin 8 homointeractions in living cells via quantitative fluorescence microscopy. We demonstrate that Tetraspanin 8 exists in a monomer-dimer equilibrium in the plasma membrane. Tetraspanin 8 dimerization is described by a high dissociation constant (Kd = 14 700 ± 1100 Tspan8/µm2), one of the highest dissociation constants measured for membrane proteins in live cells. We propose that this high dissociation constant, and thus the short lifetime of the Tetraspanin 8 dimer, is critical for Tetraspanin 8 functioning as a master regulator of cell signaling.

Neural network strategies for plasma membrane selection in fluorescence microscopy images.

In recent years, there has been an explosion of fluorescence microscopy studies of live cells in the literature. The analysis of the images obtained in these studies often requires labor-intensive manual annotation to extract meaningful information. In this study, we explore the utility of a neural network approach to recognize, classify, and select plasma membranes in high-resolution images, thus greatly speeding up data analysis and reducing the need for personnel training for highly repetitive tasks. Two different strategies are tested: 1) a semantic segmentation strategy, and 2) a sequential application of an object detector followed by a semantic segmentation network. Multiple network architectures are evaluated for each strategy, and the best performing solutions are combined and implemented in the Recognition Of Cellular Membranes software. We show that images annotated manually and with the Recognition Of Cellular Membranes software yield identical results by comparing Förster resonance energy transfer binding curves for the membrane protein fibroblast growth factor receptor 3. The approach that we describe in this work can be applied to other image selection tasks in cell biology.

Sleep apnoea has a dose-dependent effect on atrial remodelling in paroxysmal but not persistent atrial fibrillation: a high-density mapping study.

AIMS: Obstructive sleep apnoea (OSA) associates with atrial fibrillation (AF), but the relationship of OSA severity and AF phenotype with the atrial substrate remains poorly defined. We sought to define the atrial substrate across the spectrum of OSA severity utilizing high-density mapping. METHODS AND RESULTS: Sixty-six consecutive patients (male 71%, age 61 ± 9) having AF ablation (paroxysmal AF 36, persistent AF 30) were recruited. All patents underwent formal overnight polysomnography and high-density left atrial (LA) mapping (mean 2351 ± 1244 points) in paced rhythm. Apnoea-hypopnoea index (AHI) (mean 21 ± 18) associated with lower voltage (-0.34, P = 0.005), increased complex points (r = 0.43, P < 0.001), more low-voltage areas (r = 0.42, P < 0.001), and greater voltage heterogeneity (r = 0.39, P = 0.001), and persisted after multivariable adjustment. Atrial conduction heterogeneity (r = 0.24, P = 0.025) but not conduction velocity (r = -0.09, P = 0.50) associated with AHI. Patchy regions of low voltage that co-localized with slowed conduction defined the atrial substrate in paroxysmal AF, while a diffuse atrial substrate predominated in persistent AF. The association of AHI with remodelling was most apparent among paroxysmal AF [LA voltage: paroxysmal AF -0.015 (-0.025, -0.005), P = 0.004 vs. persistent AF -0.006 (-0.017, 0.005), P = 0.30]. Furthermore, in paroxysmal AF an AHI ≥ 30 defined a threshold at which atrial remodelling became most evident (nil-mild vs. moderate vs. severe: 1.92 ± 0.42 mV vs. 1.84 ± 0.28 mV vs. 1.34 ± 0.41 mV, P = 0.006). In contrast, significant remodelling was observed across all OSA categories in persistent AF (1.67 ± 0.55 mV vs. 1.50 ± 0.66 mV vs. 1.55 ± 0.67 mV, P = 0.82). CONCLUSION: High-density mapping observed that OSA associates with marked atrial remodelling, predominantly among paroxysmal AF cohorts with severe OSA. This may facilitate the identification of AF patients that stand to derive the greatest benefit from OSA management.

[Challenges of Determining the Prevalence and Incidence of Urothelial Carcinoma in Early Benefit Assessment]. / Herausforderungen der Prävalenz- und Inzidenzbestimmung in der frühen Nutzenbewertung am Beispiel Urothelkarzinom.

Since the introduction of the Medicines Market Reorganization Act (AMNOG) in 2011, there have been some structural changes for pharmaceutical manufacturers, due to the early assessment of benefits in the market launch of innovative drugs. This means that the manufacturer is constantly faced with challenges in determining the target population by using prevalence and incidence. Even given the same indication, there are often different approaches and models used for estimating the target population. In bladder carcinoma, the fourth most common tumor in men, there have been many advances in the field of immunotherapy for the treatment of locally advanced or metastatic carcinomas. These can be used to compare existing dossiers. The aim of this study was to evaluate the quality of the prevalence and incidence calculations of the dossiers in the indication urothelial carcinoma and to identify the recommendations for action that can be derived for their future determination. This problem was examined based on the methods paper of the Institute for Quality and Efficiency in Health Care and the benefit assessments of the decisions on additional benefits. Our comparison showed similarities in the use of epidemiological measures, but identified mainly differences in the calculation steps of the target population. As a result, the target population was mostly underestimated or overestimated. The quality of the dossiers differed mostly in the traceability of the calculations and the origin of data. With regard to external validity and generalizability to the German health care system, there is still room for improvement.

Indirect costs associated with ulcerative colitis: a systematic literature review of real-world data.

BACKGROUND: The economic burden of ulcerative colitis (UC), specifically related to indirect costs, is not extensively documented. Understanding and quantifying it is required by health care decision makers. AIM: To assess the impact of indirect costs of UC in observation studies. METHOD: A systematic literature search was conducted in MEDLINE®, Embase® and Cochrane Library to capture all relevant publications reporting outcomes on absenteeism, presenteeism and productivity losses in moderate to severe UC. Eligibility criteria for inclusion into the review were established using a predefined PICOS scheme. All costs were adjusted to 2017 currency values (USD dollars, $). RESULTS: In total, 18 studies reporting data on indirect costs were included in the analysis. Absenteeism costs were classified into three categories: sick leave, short-term and long-term disability. Most of the studies captured absenteeism costs related specifically to sick leave, which was experienced on average by 10 to 24% patients with UC. Only three studies captured presenteeism costs, as these are difficult to measure, however costs ranged from 1602 $ to 2947 $ per patient year. The proportion of indirect costs accounted for 35% of total UC costs (Total UC costs were defined as the sum of healthcare costs, productivity costs and out-of-pocket costs). DISCUSSION: A limited number of studies were identified describing the indirect costs in patients with moderate to severe UC. Insufficient data on different components of costs allowed a limited analysis on the impact of indirect costs in patients with UC. Further studies are needed to gain an understanding of the influence of UC on patients' functional abilities.

Cooperative interactions between VEGFR2 extracellular Ig-like subdomains ensure VEGFR2 dimerization.

BACKGROUND: Prior studies have suggested that the interactions occurring between VEGFR2 extracellular domains in the absence of ligand are complex. Here we seek novel insights into these interactions, and into the role of the different Ig-like domains (D1 through D7) in VEGFR2 dimerization. METHODS: We study the dimerization of a single amino acid mutant and of three deletion mutants in the plasma membrane using two photon microscopy and fully quantified spectral imaging. RESULTS: We demonstrate that a set of cooperative interactions between the different Ig-like domains ensure that VEGFR2 dimerizes with a specific affinity instead of forming oligomers. CONCLUSIONS: The contributions of subunits D7 and D4 seem to be the most critical, as they appear essential for strong lateral interactions and for the formation of dimers, respectively. GENERAL SIGNIFICANCE: This study provides new insights into the mechanism of VEGFR2 dimerization and activation.

Cost-effectiveness of adding novel or group 5 interventions to a background regimen for the treatment of multidrug-resistant tuberculosis in Germany.

BACKGROUND: Treatment of multidrug-resistant tuberculosis (MDR-TB) is complex, lengthy, and involves a minimum of four drugs termed a background regimen (BR), that have not previously been prescribed or that have proven susceptible to patient sputum culture isolates. In recent years, promising new treatment options have emerged as add-on therapies to a BR. The aim of this study was to evaluate the long-term costs and effectiveness of adding the novel or group 5 interventions bedaquiline, delamanid, and linezolid to a background regimen (BR) of drugs for the treatment of adult patients with pulmonary multidrug-resistant tuberculosis (MDR-TB), within their marketing authorisations, from a German healthcare cost-effectiveness perspective. METHODS: A cohort-based Markov model was developed to simulate the incremental cost-effectiveness ratio of bedaquiline plus BR, delamanid plus BR, or linezolid plus BR versus BR alone in the treatment of MDR-TB, over a 10-year time horizon. Effectiveness of treatment was evaluated in Quality-Adjusted Life-Years (QALYs) and Life-Years Gained (LYG), using inputs from clinical trials for bedaquiline and delamanid and from a German observational study for linezolid. Cost data were obtained from German Drug Directory costs (€/2015), published literature, and expert opinion. A 3% yearly discount rate was applied. Probabilistic and deterministic sensitivity analyses were conducted. RESULTS: The total discounted costs per-patient were €85,575 for bedaquiline plus BR, €81,079 for delamanid plus BR, and €80,460 for linezolid plus BR, compared with a cost of €60,962 for BR alone. The total discounted QALYs per-patient were 5.95 for bedaquiline plus BR, 5.36 for delamanid plus BR, and 3.91 for linezolid plus BR, compared with 3.68 for BR alone. All interventions were therefore associated with higher QALYs and higher costs than BR alone, with incremental costs per QALY gained of €22,238 for bedaquiline, €38,703 for delamanid, and €87,484 for linezolid, versus BR alone. In a fully incremental analysis, bedaquiline plus BR was the most cost-effective treatment option at thresholds greater than €22,000 per QALY gained. In probabilistic analyses, the probability that bedaquiline plus BR was the most cost-effective treatment strategy at a willingness-to-pay threshold of €30,000 was 54.5%, compared with 22.9% for BR alone, 18.2% for delamanid plus BR, and 4.4% for linezolid. CONCLUSIONS: In Germany, the addition of bedaquiline, delamanid, or linezolid to a BR would result in QALY gains over BR alone. Based on this analysis, bedaquiline is likely to be the most cost-effective intervention for the treatment of MDR-TB, when added to a BR regimen at thresholds greater than €22,000 per QALY.

First-line therapy for non-transplant eligible patients with multiple myeloma: direct and adjusted indirect comparison of treatment regimens on the existing market in Germany.

OBJECTIVES: The purpose of this study was to compare approved first-line therapies for patients with multiple myeloma. METHODS: A systematic literature search for phase III randomized controlled trials (RCTs) comparing first-line chemotherapies approved in Germany and recommended by guidelines at the time of study design was conducted. Random-effects meta-analysis (MA) was used for direct and the Bucher method for adjusted indirect treatment comparison. RESULTS: One RCT comparing melphalan and prednisone plus bortezomib (VMP) vs. melphalan and prednisone (MP) and six RCTs comparing MP plus thalidomide (MPT) vs. MP were analysed. For MPT vs. MP, an individual patient data (IPD) MA was used for sensitivity analyses. VMP and MPT were superior to MP regarding efficacy endpoints (VMP vs. MP, overall survival (OS): hazard ratio (HR) 0.70, 95 % confidence interval (CI) 0.57-0.86; progression-free survival (PFS): HR 0.56, 0.39-0.79; complete response (CR), risk-ratio (RR) for non-response: 0.70, 0.65-0.75; MPT vs. MP, OS: HR 0.83, 0.66-1.03; PFS: HR 0.67, 0.56-0.81; CR, RR for non-response 0.92, 0.88-0.95); but had a higher risk of developing any grade 3-4 adverse events (AEs) (VMP vs. MP: RR 1.13, 1.06-1.20; MPT vs. MP: RR 2.06, 1.43-2.98). The indirect comparison of VMP vs. MPT via MP showed a statistically not significant advantage for VMP regarding survival outcomes (OS: HR 0.85, 0.63-1.14; PFS: HR 0.83, 0.56-1.23) and a significant advantage regarding CR (RR for non-response 0.76, 0.70-0.83) and AEs (RR 0.55, 0.38-0.80). Treatment comparisons using results of IPD MA yielded similar effect sizes. CONCLUSIONS: VMP and MPT seem more effective than MP, VMP was superior to MPT regarding response criteria and AEs. Our results may best be confirmed by a head-to-head trial of VMP vs. MPT.

Probing phosphorylation events in biological membranes: The transducer function.

The extracellular environment is sensed by receptors in the plasma membrane. Some of these receptors initiate cytoplasmic signaling cascades involving phosphorylation: the addition of a phosphate group to a specific amino acid, such as tyrosine, in a protein. Receptor Tyrosine Kinases (RTKs) are one large class of membrane receptors that can directly initiate signaling cascades through their intracellular kinase domains, which both catalyze tyrosine phosphorylation and get phosphorylated. In the first step of signaling, the ligands stabilize phosphorylation-competent RTK dimers and oligomers, which leads to the phosphorylation of specific tyrosine residues in the activation loop of the kinases. Here we discuss quantitative measurements of tyrosine phosphorylation efficiencies for RTKs, described by the "transducer function". The transducer function links the phosphorylation (the response) and the binding of the activating ligand to the receptor (the stimulus). We overview a methodology that allows such measurements in direct response to ligand binding. We discuss experiments which demonstrate that EGF is a partial agonist, and that two tyrosines in the intracellular domain of EGFR, Y1068 and Y1173, are differentially phosphorylated in the EGF-bound EGFR dimers.

Switching within versus out of class following first-line TNFi failure in ulcerative colitis: real-world outcomes from a German claims data analysis.

Background: Biologic agents have demonstrated efficacy in treating ulcerative colitis (UC); however, treatment failure to tumor necrosis factor inhibitors (TNFi) is common in the real world. Data on preferential sequencing in clinical practice after failure remain limited. Objectives: This study aimed to evaluate real-world outcomes of patients cycling to TNFis or switching to non-TNFi biologics following first-line failure with TNFis. Design: Retrospective cohort study in Germany. Methods: Adult patients with UC were identified using administrative claims data from 1 May 2014 to 30 June 2022 provided by a statutory sickness fund. Patients newly initiating first-line therapy with TNFis and then switching to another agent were identified. Patients were defined as within-class switched (WCS), if they cycled to another TNFi, or outside-class switchers (OCS), if they switched to a non-TNFi biologic [ustekinumab (UST) or vedolizumab (VDZ)] and followed from index (switch date) to death, insurance end, or study end on 30 June 2022. Inverse probability of treatment weighting (IPTW) was performed to adjust for differences in baseline characteristics between groups, and weighted Cox regression models were used to compare primary (time to discontinuation and second treatment switch) and secondary outcomes (corticosteroid-free drug survival). Results: We identified 166 patients initiating TNFis and switching to a subsequent treatment (mean age: 42.9 years, 49.4% female). Following IPTW, there were 71 and 76 patients in the WCS and OCS groups, respectively. Compared to OCS, WCS were more likely to discontinue the new therapy [hazard ratio (HR), 1.82, 95% confidence interval (CI), 1.14-2.89, p = 0.012], and switch a second time (HR, 3.46, 95% CI, 1.89-6.36, p < 0.001). Moreover, WCS showed an increased likelihood of initiating prolonged corticosteroid therapy (HR, 1.42, 95% CI, 0.77-2.59, p = 0.260); however, the results were not significant. Conclusion: Following first-line TNFi failure, this study suggests that real-world outcomes among patients with UC are less favorable when cycling to another TNFi, compared to switching to a non-TNFi such as UST or VDZ.

Quantification of ligand and mutation-induced bias in EGFR phosphorylation in direct response to ligand binding.

Signaling bias is the ability of a receptor to differentially activate downstream signaling pathways in response to different ligands. Bias investigations have been hindered by inconsistent results in different cellular contexts. Here we introduce a methodology to identify and quantify bias in signal transduction across the plasma membrane without contributions from feedback loops and system bias. We apply the methodology to quantify phosphorylation efficiencies and determine absolute bias coefficients. We show that the signaling of epidermal growth factor receptor (EGFR) to EGF and TGFα is biased towards Y1068 and against Y1173 phosphorylation, but has no bias for epiregulin. We further show that the L834R mutation found in non-small-cell lung cancer induces signaling bias as it switches the preferences to Y1173 phosphorylation. The knowledge gained here challenges the current understanding of EGFR signaling in health and disease and opens avenues for the exploration of biased inhibitors as anti-cancer therapies.

Masking the transmembrane region of the amyloid ß precursor protein as a safe means to lower amyloid ß production.

Introduction: Reducing brain levels of both soluble and insoluble forms of amyloid beta (Aß) remains the primary goal of most therapies that target Alzheimer's disease (AD). However, no treatment has so far resulted in patient benefit, and clinical trials of the most promising drug candidates have generally failed due to significant adverse effects. This highlights the need for safer and more selective ways to target and modulate Aß biogenesis. Methods: Peptide technology has advanced to allow reliable synthesis, purification, and delivery of once-challenging hydrophobic sequences. This is opening up new routes to target membrane processes associated with disease. Here we deploy a combination of atomic detail molecular dynamics (MD) simulations, living-cell Förster resonance energy transfer (FRET), and in vitro assays to elucidate the atomic-detail dynamics, molecular mechanisms, and cellular activity and selectivity of a membrane-active peptide that targets the Aß precursor protein (APP). Results: We demonstrate that Aß biogenesis can be downregulated selectively using an APP occlusion peptide (APPOP). APPOP inhibits Aß production in a dose-dependent manner, with a mean inhibitory concentration (IC50) of 450 nM toward exogenous APP and 50 nM toward endogenous APP in primary rat cortical neuronal cultures. APPOP does not impact the γ-secretase cleavage of Notch-1, or exhibit toxicity toward cultured primary rat neurons, suggesting that it selectively shields APP from proteolysis. Discussion: Drugs targeting AD need to be given early and for very long periods to prevent the onset of clinical symptoms. This necessitates being able to target Aß production precisely and without affecting the activity of key cellular enzymes such as γ-secretase for other substrates. Peptides offer a powerful way for targeting key pathways precisely, thereby reducing the risk of adverse effects. Here we show that protecting APP from proteolytic processing offers a promising route to safely and specifically lower Aß burden. In particular, we show that the amyloid pathway can be targeted directly and specificically. This reduces the risk of off-target effects and paves the way for a safe prophylactic treatment.

Cost per responder analysis of guselkumab versus targeted therapies in the treatment of moderate to severe plaque psoriasis in Germany.

BACKGROUND: The fully human monoclonal antibody guselkumab is an effective treatment option for patients with moderate to severe psoriasis. OBJECTIVE: The objective of this study was to examine the cost per responder of guselkumab compared with other targeted therapies for the treatment of moderate to severe plaque psoriasis in Germany. METHODS: A one-year cost per responder model was developed based on efficacy and safety data from a published network meta-analysis. Drug, treatment administration, resource use, and adverse event costs were included in the analysis. The primary analysis assessed the cost per Psoriasis Area and Severity Index (PASI) 90 responder at week 16. Additional analyses were conducted at year 1. In the year 1 analyses, treatment response was assessed at the end of the induction period (week 16) to determine which patients continued onto maintenance therapy (responders) and which patients moved onto a subsequent adalimumab or secukinumab therapy (non-responders). RESULTS: At week 16, the cost per PASI 90 responder was lower for guselkumab than all comparators except adalimumab and brodalumab. Similarly, in the year 1 analyses, guselkumab had a lower cost per PASI 90 responder than all comparators except brodalumab. CONCLUSIONS: Guselkumab is a cost-effective therapy option in Germany.

Direct quantification of ligand-induced lipid and protein microdomains with distinctive signaling properties.

Lipid rafts are ordered lipid domains that are enriched in saturated lipids, such as the ganglioside GM1. While lipid rafts are believed to exist in cells and to serve as signaling platforms through their enrichment in signaling components, they have not been directly observed in the plasma membrane without treatments that artificially cluster GM1 into large lattices. Here, we report that microscopic GM1-enriched domains can form, in the plasma membrane of live mammalian cells expressing the EphA2 receptor tyrosine kinase in response to its ligand ephrinA1-Fc. The GM1-enriched microdomains form concomitantly with EphA2-enriched microdomains. To gain insight into how plasma membrane heterogeneity controls signaling, we quantify the degree of EphA2 segregation and study initial EphA2 signaling steps in both EphA2-enriched and EphA2-depleted domains. By measuring dissociation constants, we demonstrate that the propensity of EphA2 to oligomerize is similar in EphA2-enriched and -depleted domains. However, surprisingly, EphA2 interacts preferentially with its downstream effector SRC in EphA2-depleted domains. The ability to induce microscopic GM1-enriched domains in live cells using a ligand for a transmembrane receptor will give us unprecedented opportunities to study the biophysical chemistry of lipid rafts.

Severe Tachycardia Associated with Psychotropic Medications in Psychiatric Inpatients: A Study of Hospital Medical Emergency Team Activation.

The use of antipsychotic medications is associated with side effects, but the occurrence of severe tachycardia (heart rate ≥ 130 per minute) is not well described. The aim of this study was to determine the frequency and strength of the association between antipsychotic use and severe tachycardia in an inpatient population of patients with mental illness, while considering factors which may contribute to tachycardia. We retrospectively analyzed data from 636 Medical Emergency Team (MET) calls occurring in 449 psychiatry inpatients in three metropolitan hospitals co-located with acute medical services, and used mixed-effects logistic regression to model the association between severe tachycardia and antipsychotic use. The median age of patients was 42 years and 39% had a diagnosis of schizophrenia or psychotic disorder. Among patients who experienced MET calls, the use of second-generation (atypical) antipsychotics was commonly encountered (70%), but the use of first-generation (conventional) antipsychotics was less prevalent (10%). Severe tachycardia was noted in 22% of all MET calls, and sinus tachycardia was the commonest cardiac rhythm. After adjusting for age, anticholinergic medication use, temperature >38 °C and hypoglycemia, and excluding patients with infection and venous thromboembolism, the odds ratio for severe tachycardia with antipsychotic medication use was 4.09 (95% CI: 1.64 to 10.2).

Observational cohort study of the triggers, diagnoses and outcomes of the medical emergency team (MET) response in adult psychiatry inpatients colocated with acute medical services in Australia.

OBJECTIVES: Medical emergencies in psychiatric inpatients are challenging due to the model of care and limited medical resources. The study aims were to determine the triggers and outcomes of a medical emergency team (MET) call in psychiatric wards, and the risk factors for MET activation and mortality. DESIGN: Retrospective multisite cohort study. SETTING: Psychiatry units colocated with acute medical services at three major metropolitan hospitals in Melbourne, Australia. PARTICIPANTS: We studied 487 adult inpatients who experienced a total of 721 MET calls between January 2015 and January 2020. Patients were relatively young (mean age, 45 years) and had few medical comorbidities, but a high prevalence of smoking, excessive alcohol intake and illicit drug use. OUTCOME MEASURES: We performed a descriptive analysis of the triggers and outcomes (transfer rates, investigations, final diagnosis) of MET calls. We used logistic regression to determine the factors associated with the primary outcome of inpatient mortality, and the secondary outcome of the need for specific medical treatment compared with simple observation. RESULTS: The most common MET triggers were a reduced Glasgow Coma Scale, tachycardia and hypotension, and 49% of patients required transfer. The most frequent diagnosis was a drug adverse effect or toxidrome, followed by infection and dehydration. There was a strong association between a leave of absence and MET calls, tachycardia and the final diagnosis of drug adverse effects. Mortality occurred in 3% after MET calls. Several baseline and MET clinical variables were associated with mortality but a model with age (per 10 years, OR 1.61, 95% CI 1.29 to 2.01) and hypoxia (OR 3.59, 95% CI 1.43 to 9.04) independently predicted mortality. CONCLUSION: Vigilance is required in patients returning from day leave, and drug adverse effects remain a challenging problem in psychiatric units. Hypoxic older patients with cardiovascular comorbidity have a higher risk of death.