Harnessing a real-time location system for contact tracing in a busy emergency department.

BACKGROUND: With the persistent threat of emerging infectious diseases (EIDs), digital contact tracing (CT) tools can augment conventional CT for the prevention of healthcare-associated infectious disease transmission. However, their performance has yet to be evaluated comprehensively in the fast-paced emergency department (ED) setting. OBJECTIVE: This study compared the CT performance of a radiofrequency identification (RFID)-based real-time location system (RTLS) with conventional electronic medical record (EMR) review against continuous direct observation of close contacts ('gold standard') in a busy ED during the coronavirus disease 2019 pandemic period. METHODS: This cross-sectional study was conducted at the ED of a large tertiary care hospital in Singapore from December 2020 to April 2021. CT performance [sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and kappa] of the RTLS, EMR review and a combination of the two approaches (hybrid CT) was compared with direct observation. Finally, the mean absolute error (MAE) in the duration of each contact episode found via the RTLS and direct observation was calculated. RESULTS: In comparison with EMR review, both the RTLS and the hybrid CT approach had higher sensitivity (0.955 vs 0.455 for EMR review) and a higher NPV (0.997 vs 0.968 for EMR review). The RTLS had the highest PPV (0.777 vs 0.714 for EMR review vs 0.712 for hybrid CT). The RTLS had the strongest agreement with direct observation (kappa=0.848). The MAE between contact durations of 80 direct observations and their respective RTLS contact times was 1.81 min. CONCLUSION: The RTLS was validated to be a high-performing CT tool, with significantly higher sensitivity than conventional CT via EMR review. The RTLS can be used with confidence in time-strapped EDs for time-sensitive CT for the prevention of healthcare-associated transmission of EIDs.

First nosocomial cluster of COVID-19 due to the Delta variant in a major acute care hospital in Singapore: investigations and outbreak response.

OBJECTIVES: The first large nosocomial cluster of coronavirus disease 2019 (COVID-19) in Singapore in April 2021 led to partial closure of a major acute care hospital. This study examined factors associated with infection among patients, staff and visitors; investigated the possible role of aerosol-based transmission; evaluated the effectiveness of BNT162.b2 and mRNA1273 vaccines; and described the successful containment of the cluster. METHODS: Close contacts of patients with COVID-19 and the affected ward were identified and underwent surveillance for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Patient, staff and visitor cohorts were constructed and factors associated with infection were evaluated. Phylogenetic analysis of patient samples was performed. Ward air exhaust filters were tested for SARS-CoV-2. RESULTS: In total, there were 47 cases, comprising 29 patients, nine staff, six visitors and three household contacts. All infections were of the Delta variant. Ventilation studies showed turbulent air flow and swabs from air exhaust filters were positive for SARS-CoV-2. Vaccine breakthrough infections were seen in both patients and staff. Among patients, vaccination was associated with a 79% lower odds of infection with COVID-19 (adjusted odds ratio 0.21, 95% confidence interval 0.05-0.95). CONCLUSIONS: This cluster occurred despite enhancement of infection control measures that the hospital had undertaken at the onset of the COVID-19 pandemic. It was brought under control rapidly through case isolation, extensive contact tracing and quarantine measures, and led to enhanced use of hospital personal protective equipment, introduction of routine rostered testing of inpatients and staff, and changes in hospital infrastructure to improve ventilation within general wards.

Quantifying the natural history of breast cancer.

BACKGROUND: Natural history models of breast cancer progression provide an opportunity to evaluate and identify optimal screening scenarios. This paper describes a detailed Markov model characterising breast cancer tumour progression. METHODS: Breast cancer is modelled by a 13-state continuous-time Markov model. The model differentiates between indolent and aggressive ductal carcinomas in situ tumours, and aggressive tumours of different sizes. We compared such aggressive cancers, that is, which are non-indolent, to those which are non-growing and regressing. Model input parameters and structure were informed by the 1978-1984 Ostergotland county breast screening randomised controlled trial. Overlaid on the natural history model is the effect of screening on diagnosis. Parameters were estimated using Bayesian methods. Markov chain Monte Carlo integration was used to sample the resulting posterior distribution. RESULTS: The breast cancer incidence rate in the Ostergotland population was 21 (95% CI: 17-25) per 10 000 woman-years. Accounting for length-biased sampling, an estimated 91% (95% CI: 85-97%) of breast cancers were aggressive. Larger tumours, 21-50 mm, had an average sojourn of 6 years (95% CI: 3-16 years), whereas aggressive ductal carcinomas in situ took around half a month (95% CI: 0-1 month) to progress to the invasive ≤10 mm state. CONCLUSION: These tumour progression rate estimates may facilitate future work analysing cost-effectiveness and quality-adjusted life years for various screening strategies.

Longitudinal study of the socio-demographic determinants of changes in body weight and waist circumference in a multi-ethnic Asian population.

OBJECTIVE: To examine the changes in weight and waist circumference of adult Singaporeans between 1998 and 2005-2007, and the associations of these changes with demographic and socio-economic factors. METHODOLOGY: A prospective study, which followed up participants aged 18-69 years from the 1998 National Health Survey. Analysis was performed on data from 2483 individuals (53% of original sample) who returned for follow-up in 2005-2007. Body weight and waist circumference were measured both at baseline and follow-up. Logistic regression was used to examine factors associated with being overweight and obese at baseline. Linear regression was used to examine changes in weight and waist circumference over time. The variables examined were age, gender, ethnicity, marital status, educational level, housing and employment status, smoking, alcohol consumption and sports activities. RESULTS: Mean weight for the population increased over the follow-up period by 1.48 kg (s.d.=4.95) and mean waist circumference increased by 3.32 cm (s.d.=7.92). Cross-sectionally, those who were overweight or obese were more likely to be Malays or Indians, married, homemakers and have lower educational level. Prospectively, individuals who gained the most weight were younger, more likely to be ethnic minority groups and have the lowest body mass index (BMI) at baseline. They also appeared to be of higher socio-economic status (SES) based on housing type. These associations were statistically significant even after adjusting for other variables. CONCLUSION: Obesity prevention should start early in the younger age. Preventive programs need to reach out to Malay and Indian ethnic groups and those with higher SES. These findings should be used in designing messaging of preventive strategies.

Osteosarcoma of the rib.

This case describes the radiological-surgical correlation of a rare case of osteosarcoma of the rib in a 15-year-old boy. Successful repair of his chest wall defect using a wire mesh following extensive surgical resection of the tumour is highlighted, such a procedure being the first instituted at our centre.