Development and internal validation of a diagnostic prediction model for COVID-19 at time of admission to hospital

BACKGROUND

Early coronavirus disease 2019 (COVID-19) diagnosis prior to laboratory testing results is crucial for infection control in hospitals. Models exist predicting COVID-19 diagnosis, but significant concerns exist regarding methodology and generalizability.

AIM

To generate the first COVID-19 diagnosis risk score for use at the time of hospital admission using the TRIPOD (transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) checklist.

DESIGN

A multivariable diagnostic prediction model for COVID-19 using the TRIPOD checklist applied to a large single-centre retrospective observational study of patients with suspected COVID-19.

METHODS

581 individuals were admitted with suspected COVID-19; the majority had laboratory-confirmed COVID-19 (420/581, 72.2%). Retrospective collection was performed of electronic clinical records and pathology data.

RESULTS

The final multivariable model demonstrated AUC 0.8535 (95% confidence interval 0.8121-0.8950). The final model used six clinical variables that are routinely available in most low and high-resource settings. Using a cut-off of 2, the derived risk score has a sensitivity of 78.1% and specificity of 86.8%. At COVID-19 prevalence of 10% the model has a negative predictive value (NPV) of 96.5%.

CONCLUSIONS

Our risk score is intended for diagnosis of COVID-19 in individuals admitted to hospital with suspected COVID-19. The score is the first developed for COVID-19 diagnosis using the TRIPOD checklist. It may be effective as a tool to rule out COVID-19 and function at different pandemic phases of variable COVID-19 prevalence. The simple score could be used by any healthcare worker to support hospital infection control prior to laboratory testing results.

110 A Single Centre Study on the Thirty-Day Hospital Reattendance and Readmission of Older Patients During the SARS-CoV-2 Pandemic

Introduction

Hospital and social care suffered major alterations during the SARS-CoV-2 pandemic in the UK. Older adults were disproportionally affected by routine care disruption. To our knowledge, no data has been published so far on the impact of service disruption on 30-day readmission.

Methods

We performed a retrospective observational study of all patients admitted to a single east London hospital with laboratory-confirmed or clinical diagnosis of COVID-19 between 16th March and 6th April 2020. Older patients were defined as aged 80 years and over. Readmission was captured within 30 days of discharge. Comparator defined as the same period in 2019. Descriptive statistics were used.

Results

Three hundred and ninety-three patients were included. The majority survived to discharge (69.7%). Positive laboratory testing was similar between older and younger patients (85.7% vs 84.7%, p = NS). Mortality was significantly higher for older patients on index presentation (60.2% vs 20.3%, p < 0.001). Length of stay was also significantly longer for these patients (median 9 vs 7 days, p = 0.00694). The readmission rate for the 274 individuals discharged after index admission was 11.3% (n = 31). Amongst older patients, readmission rate during the study period was slightly higher than the same period in 2019 (17.9% vs 14.8%, p = 0.36). The median time interval between discharge and re-attendance was 8 [1–29]days. All re-attending older patients were re-admitted, whereas 54.2% of younger patients were sent home directly from the emergency department. Only 1 of the 31 patients re-attended because of insufficient social care.

Conclusions

Our data shows that readmission rates in the older population of East London during the SARS-CoV-2 pandemic were largely similar to non-pandemic periods. During this period, readmission rates appear to have been driven by clinical rather than social imperatives. This suggests that adapted social care services performed well and should be reinforced for future surges.

Systematic review of the efficacy and safety of biological therapy for inflammatory conditions in HIV-infected individuals

Biologic therapies are injectable immunomodulatory agents directed against specific immune cell or chemical targets. They have transformed the lives of HIV-uninfected individuals with severe inflammatory conditions including psoriasis, rheumatoid arthritis, and ulcerative colitis. The perceived increased infection risk associated with these agents means that HIV-infected individuals have not been included in randomised control trials of these drugs. The literature for use of biologic therapies in HIV-infected populations is limited to case reports and case series. There are additional data on use of rituximab, a monoclonal antibody against B lymphocytes, in the setting of HIV-associated haematological malignancy. We performed a systematic review of efficacy and safety of biologic therapy for inflammatory conditions in HIV-infected individuals. Our systematic review identified 37 treatment episodes with six different biologic agents encompassing 10 different inflammatory conditions. Broadly, efficacy of the agents studied was comparable to reports from HIV-uninfected patients. Both infectious and non-infectious sequelae were also comparable with trial data from HIV-uninfected patients. HIV control, even for the minority of individuals not receiving anti-retroviral therapy (ART) at the time of biologic therapy, was not adversely affected. However, detail was limited concerning ART regimens and both immunological and virological parameters of follow-up. Overall available literature is of very low quality and likely subject to publication bias of successful cases. Firm conclusions are not possible regarding the efficacy and safety of biologic agents in HIV-infected individuals; however, there appear to be sufficient data to warrant inclusion of individuals with well-controlled HIV in future trial studies.

[THE PREVALENCE OF SUBCLINICAL MYOCARDITIS AMONG YOUNG CHILDREN WITH ACUTE VIRAL INFECTION]

BACKGROUND

Viruses are the most prevalent ausative agents of myocarditis in young children. Studies have shown acute myocarditis in post mortem examinations during viral disease outbreaks. The aims of this study are to assess the prevalence of and risk factors for subclinical acute myocarditis in young children hospitalized with an acute viral disease.

OBJECTIVES

Evaluation of the prevalence of asymptomatic myocarditis or decrease in heart functions during viral infection.

METHODS

A prospective study was conducted between 1st January and 30th September, 2009. The study included 45 children 3-60 months old hospitalized with febrile illness with no clinical or microbiological evidence of acute bacterial infection. Serum levels of troponin were obtained, and ECG and echocardiography were performed in all the children. Parameters that determined myocarditis included: (1) ECG ST-T changes suggestive of myocarditis; (2) Increased serum troponin level; (3) Echocardiography findings including: shortening fraction less than 28%, left ventricle end diastolic diameter > than 2 standard deviations for age, abnormal mitral valve incompetence, or abnormal diastolic function. Clinical and epidemiological data were analyzed in order to determine parameters related to findings suggestive of silent acute myocarditis.

RESULTS

In 16 (35%) children at least one parameter, and in 7 (16%) at least 2 parameters of acute myocarditis were found. Impaired diastolic function was found in 11 cases (69%), ECG changes in 5 children (35%, left ventricle dilatation in 4 (25%), and decreased shortening fraction in 3 cases (18%]. Other symptoms and signs of myocarditis were not found in any of the 16 children, and no clinical or epidemiological parameter was significantly associated with silent myocarditis.

CONCLUSIONS

In a third of the patients, some evidence of myocardial dysfunction was documented. In seven of them (16% of all cases), there were two different categories of myocardial dysfunction. Those cases are suspected to be silent acute myocarditis. No clinical and epidemiological parameters associated with the disease were found. The clinical importance of this phenomenon should be determined by a long-term follow-up study.

SUMMARY

In this preliminary study, we found a high prevalence of cardiac involvement in hospitalised children with viral infections. It seems that this cardiac involvement is due to acute sub-clinical myocarditis. The importance of these findings should be evaluated.

Human milk lactoferrin is a serine protease that cleaves Haemophilus surface proteins at arginine-rich sites

Lactoferrin is a member of the lactotransferrin family of non-haem, iron-binding glycoproteins and is found at high concentrations in all human secretions, where it plays a major role in mucosal defence. In recent work, we observed that lactoferrin has proteolytic activity and attenuates the pathogenic potential of Haemophilus influenzae by cleaving and removing two putative colonization factors, namely the IgA1 protease protein and the Hap adhesin. Experiments with protease inhibitors further suggested that lactoferrin may belong to a serine protease family. In the present study we explored the mechanism of lactoferrin protease activity and discovered that mutation of either Ser259 or Lys73 results in a dramatic decrease in proteolysis. Examination of the crystal structure revealed that these two residues are located in the N-terminal lobe of the protein, adjacent to a 12-15 A cleft that separates the N-lobe and the C-lobe and that can readily accommodate large polypeptide substrates. In additional work, we found that lactoferrin cleaves IgA1 protease at an arginine-rich region defined by amino acids 1379-1386 (RRSRRSVR) and digests Hap at an arginine-rich sequence between amino acids 1016 and 1023 (VRSRRAAR). Based on our results, we conclude that lactoferrin is a serine protease capable of cleaving arginine-rich sequences. We speculate that Ser259 and Lys73 form a catalytic dyad, reminiscent of a number of bacterial serine proteases. In addition, we speculate that lactoferrin may cleave arginine-rich sequences in a variety of microbial virulence proteins, contributing to its long-recognized antimicrobial properties.

The Hemophilus influenzae Hap autotransporter is a chymotrypsin clan serine protease and undergoes autoproteolysis via an intermolecular mechanism

The Hemophilus influenzae Hap adhesin is an autotransporter protein that undergoes an autoproteolytic cleavage event resulting in extracellular release of the adhesin domain (Hap(s)) from the membrane-associated translocator domain (Hap(beta)). Hap autoproteolysis is mediated by Ser(243) and occurs at LN1036-7 and to a lesser extent at more COOH-terminal alternate sites. In the present study, we sought to further define the mechanism of Hap autoproteolysis. Site-directed mutagenesis of residues His(98) and Asp(140) identified a catalytic triad conserved among a subfamily of autotransporters and reminiscent of the SA (chymotrypsin) clan of serine proteases. Amino-terminal amino acid sequencing of histidine-tagged Hap(beta) species and site-directed mutagenesis established that autoproteolysis occurs at LT1046-7, FA1077-8, and FS1067-8, revealing a consensus target sequence for cleavage that consists of ((Q/R)(A/S)X(L/F)) at the P4 through P1 positions. Examination of a recombinant strain co-expressing a Hap derivative lacking all cleavage sites (HapDelta1036-99) and a Hap derivative lacking proteolytic activity (HapS243A) demonstrated that autoproteolysis occurs by an intermolecular mechanism. Kinetic analysis of Hap autoproteolysis in bacteria expressing Hap under control of an inducible promoter demonstrated that autoproteolysis increases as the density of Hap precursor in the outer membrane increases, confirming intermolecular cleavage and suggesting a novel mechanism for regulation of bacterial adherence and microcolony formation.

Electrophysiologic study and radiofrequency ablation in patients with intracardiac tumors and accessory pathways: is the tumor the pathway?

INTRODUCTION

There is a strong association of cardiac rhabdomyomas with the Wolff-Parkinson-White syndrome. This report describes the results of investigations in two patients with accessory pathway-mediated AV reciprocating tachycardia coexisting with intracardiac tumors.

METHODS AND RESULTS

Two patients with intracardiac tumors had mapping of the accessory pathway. Echocardiograms obtained in the electrophysiology laboratory while the ablation catheter was at the site of successful radiofrequency ablation demonstrated a close correspondence between the site of intracardiac tumor and the location of the accessory pathway.

CONCLUSIONS

These results lend support to the hypothesis that accessory pathways in patients with intracardiac tumors, such as rhabdomyomas, are not typical Kent bundles, but instead are either part of the intracardiac tumor or are closely related to the tumor. Ablation is possible in at least some patients with accessory pathways associated with intracardiac tumors.

Computational methods for defining the allowed conformational space of 16S rRNA based on chemical footprinting data

Structural models for 16S ribosomal RNA have been proposed based on combinations of crosslinking, chemical protection, shape, and phylogenetic evidence. These models have been based for the most part on independent data sets and different sets of modeling assumptions. In order to evaluate such models meaningfully, methods are required to explicitly model the spatial certainty with which individual structural components are positioned by specific data sets. In this report, we use a constraint satisfaction algorithm to explicitly assess the location of the secondary structural elements of the 16S RNA, as well as the certainty with which these elements can be positioned. The algorithm initially assumes that these helical elements can occupy any position and orientation and then systematically eliminates those positions and orientations that do not satisfy formally parameterized interpretations of structural constraints. Using a conservative interpretation of the hydroxyl radical footprinting data, the positions of the ribosomal proteins as defined by neutron diffraction studies, and the secondary structure of 16S rRNA, the location of the RNA secondary structural elements can be defined with an average precision of 25 A (ranging from 12.8 to 56.3 A). The uncertainty in individual helix positions is both heterogeneous and dependent upon the number of constraints imposed on the helix. The topology of the resulting model is consistent with previous models based on independent approaches. The result of our computation is a conservative upper bound on the possible positions of the RNA secondary structural elements allowed by this data set, and provides a suitable starting point for refinement with other sources of data or different sets of modeling assumptions.

Effect of thyrotropin-releasing hormone on the carbohydrate structure of secreted mouse thyrotropin. Analysis by lectin affinity chromatography

Thyrotropin (TSH) is a glycoprotein hormone whose secretion from the anterior pituitary is regulated, in part, by the hypothalamic tripeptide thyrotropin-releasing hormone (TRH). We have used serial lectin affinity analysis to explore whether TRH, in addition to promoting TSH secretion, alters the carbohydrate structure of secreted TSH. Hypothyroid mouse hemipituitaries were incubated in medium containing [3H] mannose, [3H]glucosamine, or [3H]fucose either with or without 10(-7) M TRH. TSH was immunoprecipitated, proteolytically digested into glycopeptides, and chromatographed on serial lectin-Sepharose columns. Under basal conditions, 37% of secreted [3H]mannose-labeled TSH glycopeptides failed to bind to concanavalin A (ConA)-Sepharose, 55% bound and eluted with 10 mM alpha-methylglucoside, and 8% bound and eluted with 500 mM alpha-methylmannoside. Approximately 35% of glycopeptides not binding to ConA-Sepharose were bound by pea lectin-Sepharose, suggesting the presence of certain core fucosylated triantennary complex oligosaccharides. TRH caused a 2-fold increase in secretion of [3H]mannose-labeled TSH glycopeptides due almost exclusively to a specific increase in structures that bound to ConA-Sepharose and eluted with 10mM alpha-methylglucoside, corresponding to biantennary complex or unusual hybrid species. There was no change in the distribution of intrapituitary TSH glycopeptides with TRH. Acid hydrolysis of secreted proteins showed little metabolism of the tritiated sugar precursors, except for a 20% conversion of [3H]mannose to [3H]fucose. Moreover, ConA-Sepharose chromatography of secreted [3H]glucosamine- and [3H]fucose-labeled TSH glycopeptides showed similar increases in ConA-Sepharose binding with TRH as noted with [3H]mannose labeling. Subsequent lectin analysis of secreted [3H] mannose-labeled TSH glycopeptides on erythroagglutinating phytohemagglutinin-Sepharose and leukoagglutinating phytohemagglutinin-Sepharose disclosed no significant differences in TRH-treated versus control samples. These data suggest that secreted mouse TSH has greater carbohydrate heterogeneity than has been recognized previously. In addition, TRH in vitro promotes the secretion of specific TSH molecules apparently enriched in biantennary complex or unusual hybrid oligosaccharides.

Reimplantation of the ampulla of Vater

Injury to the common bile duct and the pancreatic duct during duodenal ulcer or tumor surgery is exceedingly rare. In the past 50 years, only eight case reports have dealt with reimplantation of the ampulla of Vater. Reimplantation sites have included the stomach, duodenum, and jejunum. Herein we described a new technique that uses the gallbladder for reimplantation of the ampulla of Vater.

Rectus muscle preservation in oblique incisions for cholecystectomy

A technique of retraction and preservation of the rectus muscle in oblique cholecystectomy incisions is described. Preservation of the rectus increases strength and decreases the amount of devitalized tissue in the wound. Using the rectus preserving technique, no incisional hernias have developed in a series of more than 100 cholecystectomies, even when wound infections have occurred. The advantages of preserving the rectus as an accessory muscle of respiration as well as the advantages in wound strength allow for a shorter period of convalescence.

Chromic suture material as a nidus for common duct stone formation

Several surgeons have reported finding silk suture material as a nidus for common duct stones after cholecystectomy. They have therefore advocated the use of chromic sutures to ligate the cystic duct in order to avoid this complication. A case report is presented in which chromic suture material was found to be the source of common duct stone formation after cholecystectomy. A review of the literature indicated the relative infrequency of foreign suture material causing this problem. The suture used in the routine ligation of the cystic duct should be left to the technical preference of the surgeon.

Mucoid colonic carcinoma as an autosomal-dominant inherited syndrome

An autosomal-dominant mucoid colonic carcinoma syndrome is described. Seventeen members of one family over three generations have experienced cancers, including 14 with adenocarcinoma of the colon. The defective autosomal locus is pleiotropic, producing adenocarcinoma of the endometrium, atypical endometrial hyperplasia, uterine leiomyosarcoma, and bladder transitional and renal cell carcinoma in addition to the mucoid variant of colon carcinoma.