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The Covid-19 pandemic has focused attention on airborne transmission of viruses. Using realistic air flow simulation, we model droplet dispersion from coughing and study the transmission risk related to SARS-CoV-2. Although this model defines most airborne droplets as 8–16 µm in diameter, we infer that larger droplets of 32–40 µm in diameter may potentially be more infectious due to higher viral content. Use of face masks is therefore recommended for both personal and social protection. We found social distancing effective at reducing transmission potential across all droplet sizes. However, the presence of a human body 1 m away modifies the aerodynamics so that downstream droplet dispersion is enhanced, which has implications on safe distancing in queues. At 1 m distance, we found that an average of 0.55 viral copies is inhaled for a cough at median loading, scalable up to 340 copies at peak loading. Droplet evaporation results in significant reduction in droplet counts, but airborne transmission remains possible even under low humidity conditions.

Purpose The SingHealth-Duke-GlaxoSmithKline COPD and Asthma Real-world Evidence (SDG-CARE) collaboration was formed to accelerate the use of Singaporean real-world evidence in research and clinical care. A centerpiece of the collaboration was to develop a near real-time database from clinical and operational data sources to inform healthcare decision making and research studies on asthma and chronic obstructive pulmonary disease (COPD). Methods Our multidisciplinary team, including clinicians, epidemiologists, data scientists, medical informaticians and IT engineers, adopted the hybrid waterfall-agile project management methodology to develop the SingHealth COPD and Asthma Data Mart (SCDM). The SCDM was developed within the organizational data warehouse. It pulls and maps data from various information systems using extract, transform and load (ETL) pipelines. Robust user testing and data verification was also performed to ensure that the business requirements were met and that the ETL pipelines were valid. Results The SCDM includes 199 data elements relevant to asthma and COPD. Data verification was performed and found the SCDM to be reliable. As of December 31, 2019, the SCDM contained 36,407 unique patients with asthma and COPD across the spectrum from primary to tertiary care in our healthcare system. The database updates weekly to add new data of existing patients and to include new patients who fulfil the inclusion criteria. Conclusions The SCDM was systematically developed and tested to support the use RWD for clinical and health services research in asthma and COPD. This can serve as a platform to provide research and operational insights to improve the care delivered to our patients.

Introduction Asthma inhalers are significant contributors of greenhouse gas emissions. However, less is known about the potentially avoidable carbon footprint i.e. medication wastage and oversupply. We aimed to analyse dispensing patterns and carbon footprints of asthma inhalers, quantify medication wastage, and identify determinants of medication oversupply. Methods We reviewed the asthma-related dispensation records from 2015 to 2019, in an anonymised, cluster-wide repository linking electronic medical, pharmacy and administrative records, containing patient and visit details on demographics, comorbidities, GINA step, and site of care. Medication wastage, a visit-level measure, was defined as the number of inhalers dispensed in excess of the quantity required during each refill interval. Medication oversupply, a patient-level aggregated measure defined by medication possession ratio (MPR) > 1.2, where MPR equals total dispensed days (summed across all maintenance inhalers) divided by the follow-up period. All analyses were performed using R Studio. Results 205,337 inhaler units were dispensed over the study period, contributing an estimated 1,541,591 kgCO2e. The most frequently prescribed inhalers were SABA MDIs (79,007 units; 38.5%), followed by ICS-LABA MDIs (46,335 units; 22.6%), ICS MDIs (36,635 units; 17.8%), ICS-LABA DPIs (33,730 units; 16.4%), and ICS DPIs (9,630 units; 4.7%). ICS-LABA MDIs remained the greatest contributor of carbon footprint, with annual carbon emissions nearly doubling from 114,476 kgCO2e in 2015 to 214,575 kgCO2e in 2019. A total of 6,427 canisters were dispensed in excess of refill intervals, accounting for 46,798 kgCO2e. Beclomethasone MDIs accounted for the majority of wasted inhalers. In a multinomial regression analysis, patients receiving care in primary care settings were significantly more likely to be oversupplied medications compared to those in specialist care (OR 1.93, 95% CI 1.49–2.51). Conclusion ICS-LABA MDIs are the predominant source of inhaler-related carbon footprint, with additional contribution from excessive dispensation of inhalers.

Inhaled corticosteroid (ICS) is the mainstay therapy for asthma, but general adherence is low. There is a paucity of real-world inhaler prescribing and adherence data from Asia and at the population level. To address these gaps, we performed a real-world data analysis of inhaler prescribing pattern and adherence in a multi-ethnic Asian asthma cohort and evaluated the association with asthma outcomes. We performed a retrospective analysis of adult asthma patients (aged ≥18 years) treated in the primary and specialist care settings in Singapore between 2015 to 2019. Medication adherence was measured using the medication possession ratio (MPR), and categorised into good adherence (MPR 0.75-1.2), poor adherence (MPR 0.75) or medication oversupply (MPR > 1.2). All statistical analyses were performed using R Studio. 8023 patients, mean age 57 years, were evaluated between 2015 and 2019. Most patients were receiving primary care (70.4%) and on GINA step 1–3 therapies (78.2%). ICS-long-acting beta-2 agonist (ICS-LABA) users increased over the years especially in the primary care, from 33% to 52%. Correspondingly, inpatient admission and ED visit rates decreased over the years. Between 2015 and 2019, the proportion of patients with poor adherence decreased from 12.8% to 10.5% (for ICS) and from 30.0% to 26.8% (for ICS-LABA) respectively. Factors associated with poor adherence included minority ethnic groups (Odds ratio of MPR 0.75–1.2: 0.73–0.93; compared to Chinese), presence of COPD (OR 0.75, 95% CI 0.59–0.96) and GINA step 4 treatment ladder (OR 0.71, 95% CI 0.61–0.85). Factors associated with good adherence were male gender (OR 1.14, 95% CI 1.01–1.28), single site of care (OR 1.22 for primary care and OR 1.76 for specialist care), GINA step 2 treatment ladder (OR 1.28, 95% CI 1.08–1.50). Good adherence was also associated with less frequent inpatient admission (OR 0.91, 95% CI 0.84–0.98), greater SABA overdispensing (OR 1.66, 95% CI 1.47–1.87) and oral corticosteroids use (OR 1.10, 95% CI 1.05–1.14). Inhaled corticosteroid (ICS) adherence has improved generally, however, poor adherence was observed for patients receiving asthma care in both primary and specialist care, and those from the minority ethnicities.

This purpose of this study was to examine clinical-pathologic factors--particularly smoking and brain metastases--in EGFR mutation positive (M(+)) lung adenocarcinoma (ADC) to determine their impact on survival in patients treated with first line EGFR TKI. A retrospective review of EGFR mutation reflex testing experience for all ADC diagnosed at a tertiary Asian cancer centre from January 2009 to April 2013. Amongst this cohort, patients with advanced EGFR M(+) ADC treated with first line EGFR TKI were identified to determine factors that influence progression free and overall survival. 444/742 (59.8%) ADC reflex tested for EGFR mutations were EGFR M(+.) Amongst never-smokers (n=468), EGFR M(+) were found in 74.5% of females and 76.3% of males, and amongst ever smokers (n=283), in 53.3% of females and 35.6% of males. Exon 20 mutations were found more commonly amongst heavy smokers (> 50 pack years and > 20 pack years, Pearson's chi square p=0.044, and p=0.038 respectively). 211 patients treated with palliative first line TKI had a median PFS and OS of 9.2 and 19.6 months respectively. 26% of patients had brain metastasis at diagnosis. This was significantly detrimental to overall survival (HR 1.85, CI 1.09-3.16, p=0.024) on multivariate analysis. There was no evidence that smoking status had a significant impact on survival. The high prevalence of EGFR M(+) in our patient population warrants reflex testing regardless of gender and smoking status. Smoking status and dosage did not impact progression free or overall survival in patients treated with first line EGFR TKI. The presence of brain metastasis at diagnosis negatively impacts overall survival.

In the past 20 years, our understanding of acute respiratory distress syndrome (ARDS) management has improved, but the worldwide incidence and current outcomes are unclear. The reported incidence is highly variable, and no studies specifically characterise ARDS epidemiology in Asia. This observation study aims to determine the incidence, mortality and management practices of ARDS in a high income South East Asian country. We conducted a prospective, population based observational study in 6 public hospitals. During a one month period, we identified all ARDS patients admitted to public hospital intensive care units (ICU) in Singapore, according to the Berlin definition. Demographic information, clinical management data and ICU outcome data was collected. A total of 904 adult patients were admitted to ICU during the study period and 15 patients met ARDS criteria. The unadjusted incidence of ARDS was 4.5 cases per 100,000 population, accounting for 1.25% of all ICU patients. Most patients were male (75%), Chinese (62%), had pneumonia (73%), and were admitted to a Medical ICU (56%). Management strategies varied across all ICUs. In-hospital mortality was 40% and median length of ICU stay was 7 days. The incidence of ARDS in a developed S.E Asia country is comparable to reported rates in European studies.

Background Clinical practice guidelines on limitation of life-sustaining treatments (LST) in the intensive care unit (ICU), in the form of withholding or withdrawal of LST, state that there is no ethical difference between the two. Such statements are not uniformly accepted worldwide, and there are few studies on LST limitation in Asia. This study aimed to evaluate the predictors and outcomes of withholding and withdrawal of LST in Singapore, focusing on the similarities and differences between the two approaches. Methods This was a multicentre observational study of patients admitted to 21 adult ICUs across 9 public hospitals in Singapore over an average of three months per year from 2014 to 2019. The primary outcome measures were withholding and withdrawal of LST (cardiopulmonary resuscitation, invasive mechanical ventilation, and vasopressors/inotropes). The secondary outcome measure was hospital mortality. Multivariable generalised mixed model analysis was used to identify independent predictors for withdrawal and withholding of LST and if LST limitation predicts hospital mortality. Results There were 8907 patients and 9723 admissions. Of the former, 80.8% had no limitation of LST, 13.0% had LST withheld, and 6.2% had LST withdrawn. Common independent predictors for withholding and withdrawal were increasing age, absence of chronic kidney dialysis, greater dependence in activities of daily living, cardiopulmonary resuscitation before ICU admission, higher Acute Physiology and Chronic Health Evaluation (APACHE) II score, and higher level of care in the first 24 h of ICU admission. Additional predictors for withholding included being of Chinese race, the religions of Hinduism and Islam, malignancy, and chronic liver failure. The additional predictor for withdrawal was lower hospital paying class (with greater government subsidy for hospital bills). Hospital mortality in patients without LST limitation, with LST withholding, and with LST withdrawal was 10.6%, 82.1%, and 91.8%, respectively ( p  < 0.001). Withholding (odds ratio 13.822, 95% confidence interval 9.987–19.132) and withdrawal (odds ratio 38.319, 95% confidence interval 24.351–60.298) were both found to be independent predictors of hospital mortality on multivariable analysis. Conclusions Differences in the independent predictors of withholding and withdrawal of LST exist. Even after accounting for baseline characteristics, both withholding and withdrawal of LST independently predict hospital mortality. Later mortality in patients who had LST withdrawn compared to withholding suggests that the decision to withdraw may be at the point when medical futility is recognised.

Background Transbronchial needle aspiration (TBNA) is a bronchoscopic technique that provides access to masses within the mediastinum. It is operator dependent, and factors such as needle type, lymph node site, and endobronchial ultrasosonography (EBUS) have been implicated as having an impact on its accuracy. This study aimed to develop a strategy for TBNA and specimen preparation techniques as the first step toward improving TBNA yield, and to determine whether EBUS can augment its application. Methods Intervention included standardizing the use of the histology needle and the direct smear method. As competency improved, radial probe (RP) and linear EBUS were incorporated into TBNA. Results The study assessed 35 conventional TBNA procedures before and 45 of these procedures after intervention as well as 45 RP-EBUS and 50 linear EBUS-guided TBNA procedures. Frequently sampled lymph node stations were 7, 4R, and 4L in the American Thoracic Society classification. The preintervention conventional TBNA yield was 43%, which improved to 82% after intervention. Although EBUS did not have an impact on TBNA yield ( p  = 0.44) compared with the intervention ( p  = 0.001), EBUS was useful for lymph nodes smaller than 2 cm ( p  < 0.0001). Linear EBUS did not confer higher diagnostic accuracy than RP-EBUS ( p  = 0.47). Conclusion Proper TBNA and specimen preparation techniques are the first steps toward improving TBNA yield, and EBUS can be used to guide TBNA of small lymph nodes.

Guidewire retention is a severe but preventable complication from central venous catheter (CVC) insertion. There were three cases of guidewire retention during CVC insertion in the medical intensive care unit (MICU) in Singapore General Hospital, in the period between December 2011 and February 2012. The primary objective of this quality improvement project was to eliminate future incidences of guidewire retention during CVC insertion in the MICU and medical intermediate care area (MICA) via a structured educational program and a cost effective modified CVC set. The secondary objective was to perform a cost analysis and comparison between the use of the conventional hospital CVC set and drape with our newly modified CVC dressing kit.Root cause analysis of the three cases identified major factors leading to guidewire retention. Interventions were planned and tested using PDSA cycles. Internal medicine trainees rotating through MICU and MICA during the period between February 2012 and June 2013 underwent a multi-modal structured CVC insertion training program with hands on simulation. They also used a newly modified CVC dressing kit and drape. The CVC dressing kit was modified (CVC PLUS) to include a sterile drape with reminder stickers stating “REMOVE the GUIDEWIRE,” as well as a sterile ultrasound sleeve. The total number of CVC insertions performed and guidewire retentions were monitored.During the period of study there were 320 CVC insertions in the MICU and MICA. Since this quality improvement project was initiated, and up to the submission of this article, there have not been any further cases of guidewire retention in the MICU and MICA. The total cost reduction per use of CVC PLUS was S$29.26 (Singaporean Dollars).A multi-modal structured training program, integrated with a modified, pre-packed CVC set, and drapes with reminder stickers (all included in CVC PLUS) were cost effective, and improved patient safety by eliminating guidewire retention during CVC insertion.

ObjectivesTo evaluate the association between asthma-related emergency department (ED) visits and weather, air quality, monsoons, haze and cultural festivals in Singapore.DesignRetrospective cohort study.SettingA public healthcare cluster that covers 20% of the nation’s adult asthma population.Participants2617 adult patients accounting for 5337 asthma ED visits between 2016 and 2024.Primary and secondary outcome measuresTemperature, rainfall, wet bulb temperature (WBT), wind speed and Pollution Standards Index (PSI) were correlated with asthma ED counts at 0–7 day lags. Associations between ED visits and monsoons, transboundary haze and cultural festivals were evaluated using one-way analysis of variance. Weekly seasonal ARIMA models with exogenous regressors were fitted, incorporating PSI as a covariate and adjusting for demographic, clinical and socioeconomic factors.ResultsAsthma ED visits were positively correlated with PSI (lag 0: r=0.142; 95% CI 0.107 to 0.178) and inversely correlated with rainfall (lag 3: r=−0.062; 95% CI −0.099 to –0.026) and WBT (lag 1: r=−0.067; 95% CI −0.104 to −0.031). Wind speed (lag 2: r=−0.049; 95% CI −0.086 to –0.013) and ambient temperature (lag 6: r=−0.045; 95% CI −0.081 to –0.008) showed weaker inverse associations. Mean PSI was higher during haze (82.67 vs 51.46, p<0.001) and festival periods (53.42 vs 51.57, p=0.001). Mean ED visits fell across successive haze events (2.60 in 2016, 2.36 in 2019, 1.46 in 2023) but peaked during the Northeast monsoons despite lower PSI, indicating weather influences beyond ambient pollution.ConclusionsPSI–ED association peaked on the same day of exposure but was no longer significant after adjusting for demographic and clinical factors. Pollution-linked festivals, transboundary haze and the Northeast monsoon were associated with increased asthma ED visits