Budget Impact Analysis of Adopting a One-Step Nucleic Acid Amplification Testing (NAAT) Alone Diagnostic Pathway for Clostridioides difficile in Japan Compared to a Two-Step Algorithm with Glutamate Dehydrogenase/Toxin Followed by NAAT.

Clostridioides difficile infection (CDI) is a major healthcare-associated infection that leads to a significant health economic burden in Japan. Using a decision tree model, we evaluated the budget impact of adopting a one-step nucleic acid amplification test (NAAT) alone pathway compared to a two-step diagnostic algorithm with glutamate dehydrogenase (GDH) and toxin antigen, followed by NAAT. The analysis was conducted from the government payer's perspective for 100,000 symptomatic, hospitalized adults requiring a CDI diagnostic test. One-way sensitivity analysis was conducted for all data inputs. The NAAT alone strategy costed JPY 225,886,360 (USD 2,424,714) more, but was more effective, resulting in 1749 more patients accurately diagnosed and 91 fewer deaths compared to the two-step algorithm. Additionally, the NAAT alone pathway costed JPY 26,146 (USD 281) less per true positive CDI diagnosed. The total budget impact, and cost per CDI diagnosed was most sensitive to GDH sensitivity in one-way sensitivity analysis, where a lower GDH sensitivity resulted in greater cost savings with the NAAT alone pathway. Findings from this budget impact analysis can guide the adoption of a NAAT alone pathway for CDI diagnosis in Japan.

Cross-sectional study of prevalence and risk factors, and a cost-effectiveness evaluation of screening and preventive treatment strategies for latent tuberculosis among migrants in Singapore.

OBJECTIVES: WHO recommends that low burden countries consider systematic screening and treatment of latent tuberculosis infection (LTBI) in migrants from high incidence countries. We aimed to determine LTBI prevalence and risk factors and evaluate cost-effectiveness of screening and treating LTBI in migrants to Singapore from a government payer perspective. DESIGN: Cross-sectional study and cost-effectiveness analysis. SETTING: Migrants in Singapore. PARTICIPANTS: 3618 migrants who were between 20 and 50 years old, have not worked in Singapore previously and stayed in Singapore for less than a year were recruited. PRIMARY AND SECONDARY OUTCOME MEASURES: Costs, quality-adjusted life-years (QALYs), threshold length of stay, incremental cost-effectiveness ratios (ICERs), cost per active TB case averted. RESULTS: Of 3584 migrants surveyed, 20.4% had positive interferon-gamma release assay (IGRA) results, with the highest positivity in Filipinos (33.2%). Higher LTBI prevalence was significantly associated with age, marital status and past TB exposure. The cost-effectiveness model projected an ICER of S$57 116 per QALY and S$12 422 per active TB case averted for screening and treating LTBI with 3 months once weekly isoniazid and rifapentine combination regimen treatment compared with no screening over a 50-year time horizon. ICER was most sensitive to the cohort's length of stay in Singapore, yearly disease progression rates from LTBI to active TB, followed by the cost of IGRA testing. CONCLUSIONS: For LTBI screening and treatment of migrants to be cost-effective, migrants from high burden countries would have to stay in Singapore for ~50 years. Risk-stratified approaches based on projected length of stay and country of origin and/or age group can be considered.

Immune cell phenotypes associated with disease severity and long-term neutralizing antibody titers after natural dengue virus infection.

Prior immunological exposure to dengue virus can be both protective and disease-enhancing during subsequent infections with different dengue virus serotypes. We provide here a systematic, longitudinal analysis of B cell, T cell, and antibody responses in the same patients. Antibody responses as well as T and B cell activation differentiate primary from secondary responses. Hospitalization is associated with lower frequencies of activated, terminally differentiated T cells and higher percentages of effector memory CD4 T cells. Patients with more severe disease tend to have higher percentages of plasmablasts. This does not translate into long-term antibody titers, since neutralizing titers after 6 months correlate with percentages of specific memory B cells, but not with acute plasmablast activation. Overall, our unbiased analysis reveals associations between cellular profiles and disease severity, opening opportunities to study immunopathology in dengue disease and the potential predictive value of these parameters.

Engineered NS1 for Sensitive, Specific Zika Virus Diagnosis from Patient Serology.

Dengue virus (DENV) and Zika virus (ZIKV) belong to the Flaviviridae family of viruses spread by Aedes aegypti mosquitoes in tropical and subtropical areas. Accurate diagnostic tests to differentiate the 2 infections are necessary for patient management and disease control. Using characterized ZIKV and DENV patient plasma in a blind manner, we validated an ELISA and a rapid immunochromatographic test for ZIKV detection. We engineered the ZIKV nonstructural protein 1 (NS1) for sensitive serologic detection with low cross reactivity against dengue and developed monoclonal antibodies specific for the ZIKV NS1 antigen. As expected, the serologic assays performed better with convalescent than acute plasma samples; the sensitivity ranged from 71% to 88%, depending on the performance of individual tests (IgM/IgG/NS1). Although serologic tests were generally less sensitive with acute samples, our ZIKV NS1 antibodies were able to complement the serologic tests to achieve greater sensitivity for detecting early infections.

Government trust, perceptions of COVID-19 and behaviour change: cohort surveys, Singapore.

OBJECTIVE: To evaluate how public perceptions and trust in government communications affected the adoption of protective behaviour in Singapore during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: We launched our community-based cohort to assess public perceptions of infectious disease outbreaks in mid-2019. After the first case of COVID-19 was reported in Singapore on 23 January, we launched a series of seven COVID-19 surveys to both existing and regularly enrolled new participants every 2 weeks. As well as sociodemographic properties of the participants, we recorded changing responses to judge awareness of the situation, trust in various information sources and perceived risk. We used multivariable logistic regression models to evaluate associations with perceptions of risk and self-reported adopted frequencies of protective behaviour. FINDINGS: Our cohort of 633 participants provided 2857 unique responses during the seven COVID-19 surveys. Most agreed or strongly agreed that information from official government sources (99.1%; 528/533) and Singapore-based news agencies (97.9%; 522/533) was trustworthy. Trust in government communication was significantly associated with higher perceived threat (odds ratio, OR: 2.2; 95% confidence interval, CI: 1.6-3.0), but inversely associated with perceived risk of infection (OR: 0.6; 95% CI: 0.4-0.8) or risk of death if infected (OR: 0.6; 95% CI: 0.4-0.9). Trust in government communication was also associated with a greater likelihood of adopting protective behaviour. CONCLUSION: Our findings show that trust is a vital commodity when managing an evolving outbreak. Our repeated surveys provided real-time feedback, allowing an improved understanding of the interplay between perceptions, trust and behaviour.

Single molecule, near full-length genome sequencing of dengue virus.

Current methods for dengue virus (DENV) genome amplification, amplify parts of the genome in at least 5 overlapping segments and then combine the output to characterize a full genome. This process is laborious, costly and requires at least 10 primers per serotype, thus increasing the likelihood of PCR bias. We introduce an assay to amplify near full-length dengue virus genomes as intact molecules, sequence these amplicons with third generation "nanopore" technology without fragmenting and use the sequence data to differentiate within-host viral variants with a bioinformatics tool (Nano-Q). The new assay successfully generated near full-length amplicons from DENV serotypes 1, 2 and 3 samples which were sequenced with nanopore technology. Consensus DENV sequences generated by nanopore sequencing had over 99.5% pairwise sequence similarity to Illumina generated counterparts provided the coverage was > 100 with both platforms. Maximum likelihood phylogenetic trees generated from nanopore consensus sequences were able to reproduce the exact trees made from Illumina sequencing with a conservative 99% bootstrapping threshold (after 1000 replicates and 10% burn-in). Pairwise genetic distances of within host variants identified from the Nano-Q tool were less than that of between host variants, thus enabling the phylogenetic segregation of variants from the same host.

Passive immune therapy and other immunomodulatory agents for the treatment of severe influenza: Systematic review and meta-analysis.

BACKGROUND: A range of immunomodulatory therapies have been proposed as adjuncts to conventional antivirals to suppress harmful inflammation during severe influenza infection. We conducted a systematic review to assess available data of the effect of adjunctive non-corticosteroid immunomodulatory therapy and potential adverse effects. METHOD: We searched MEDLINE, Embase, Web of Science and clinical trial databases for published and unpublished studies, and screened the references of included articles. We included RCTs, quasi-RCTs and observational studies of virologically confirmed influenza infections in hospitalised patients. We did not restrict studies by language of publication, influenza type/subtype or age of participants. Where possible, we pooled estimates of effect using random-effects meta-analysis models. RESULTS: We identified 11 eligible studies for inclusion: five studies (4 RCTs and 1 observational; 693 individuals) of passive immune therapy; four studies (3 RCTs and 1 observational; 1120 individuals) of macrolides and/or non-steroidal anti-inflammatory drugs (NSAIDs), one RCT of mTOR inhibitors (38 individuals), and one RCT of statin therapy (116 individuals). Meta-analysis of RCTs of passive immune therapy indicated no significant reduction in mortality (OR 0.84, 0.37-1.90), but better clinical outcomes at Day 7 (OR 1.42, 1.05-1.92). There was a significant reduction in mortality associated with macrolides and/or NSAIDs (OR 0.28; 0.10-0.77). CONCLUSIONS: Passive immune therapy is unlikely to offer substantial mortality benefit in treatment of severe seasonal influenza, but may improve clinical outcomes. The effect of other immunomodulatory agents is uncertain, but promising. There is a need for high-quality RCTs with sufficient statistical power to address this evidence gap.

Multiplex targeted mass spectrometry assay for one-shot flavivirus diagnosis.

Targeted proteomic mass spectrometry is emerging as a salient clinical diagnostic tool to track protein biomarkers. However, its strong analytical properties have not been exploited in the diagnosis and typing of flaviviruses. Here, we report the development of a sensitive and specific single-shot robust assay for flavivirus typing and diagnosis using targeted mass spectrometry technology. Our flavivirus parallel reaction monitoring assay (fvPRM) has the ability to track secreted flaviviral nonstructural protein 1 (NS1) over a broad diagnostic and typing window with high sensitivity, specificity, extendibility, and multiplexing capability. These features, pivotal and pertinent to efficient response toward flavivirus outbreaks, including newly emerging flavivirus strains, circumvent the limitations of current diagnostic assays. fvPRM thus carries high potential in positioning itself as a forerunner in delivering early and accurate diagnosis for disease management.

Longitudinal Study of Cellular and Systemic Cytokine Signatures to Define the Dynamics of a Balanced Immune Environment During Disease Manifestation in Zika Virus-Infected Patients.

Background: Since its unexpected reemergence, Zika virus (ZIKV) has caused numerous outbreaks globally. This study characterized the host immune responses during ZIKV infection. Methods: Patient samples were collected longitudinally during the acute, convalescence and recovery phases of ZIKV infection over 6 months during the Singapore outbreak in late 2016. Plasma immune mediators were profiled via multiplex microbead assay, while changes in blood cell numbers were determined with immunophenotyping. Results: Data showed the involvement of various immune mediators during acute ZIKV infection accompanied by a general reduction in blood cell numbers for all immune subsets except CD14+ monocytes. Importantly, viremic patients experiencing moderate symptoms had significantly higher quantities of interferon γ-induced protein 10, monocyte chemotactic protein 1, interleukin 1 receptor antagonist, interleukin 8, and placental growth factor 1, accompanied by reduced numbers of peripheral CD8+ T cells, CD4+ T cells, and double-negative T cells. Levels of T-cell associated mediators, including interferon γ-induced protein 10, interferon γ, and interleukin 10, were high in recovery phases of ZIKV infection, suggesting a functional role for T cells. The identification of different markers at specific disease phases emphasizes the dynamics of a balanced cytokine environment in disease progression. Conclusions: This is the first comprehensive study that highlights specific cellular changes and immune signatures during ZIKV disease progression, and it provides valuable insights into ZIKV immunopathogenesis.

MRSA Transmission Dynamics Among Interconnected Acute, Intermediate-Term, and Long-Term Healthcare Facilities in Singapore.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common healthcare-associated multidrug-resistant organism. Despite the interconnectedness between acute care hospitals (ACHs) and intermediate- and long-term care facilities (ILTCFs), the transmission dynamics of MRSA between healthcare settings is not well understood. METHODS: We conducted a cross-sectional study in a network comprising an ACH and 5 closely affiliated ILTCFs in Singapore. A total of 1700 inpatients were screened for MRSA over a 6-week period in 2014. MRSA isolates underwent whole-genome sequencing, with a pairwise single-nucleotide polymorphism (Hamming distance) cutoff of 60 core genome single-nucleotide polymorphisms used to define recent transmission clusters (clades) for the 3 major clones. RESULTS: MRSA prevalence was significantly higher in intermediate-term (29.9%) and long-term (20.4%) care facilities than in the ACH (11.8%) (P < .001). The predominant clones were sequence type [ST] 22 (n = 183; 47.8%), ST45 (n = 129; 33.7%), and ST239 (n = 26; 6.8%), with greater diversity of STs in ILTCFs relative to the ACH. A large proportion of the clades in ST22 (14 of 21 clades; 67%) and ST45 (7 of 13; 54%) included inpatients from the ACH and ILTCFs. The most frequent source of the interfacility transmissions was the ACH (n = 28 transmission events; 36.4%). CONCLUSIONS: MRSA transmission dynamics between the ACH and ILTCFs were complex. The greater diversity of STs in ILTCFs suggests that the ecosystem in such settings might be more conducive for intrafacility transmission events. ST22 and ST45 have successfully established themselves in ILTCFs. The importance of interconnected infection prevention and control measures and strategies cannot be overemphasized.

A review of stab wound injuries at a tertiary trauma centre in Singapore: are self-inflicted ones less severe?

INTRODUCTION: In Singapore, as strict laws are a strong deterrent against armed violence, little is known about the epidemiology of penetrating stab wound injuries. Our study aimed to investigate the epidemiology of stab wound injuries at a major trauma centre in Singapore and determine if there was a difference in severity between self-inflicted stab wound (SI) injuries and those inflicted by others (IO). METHODS: We retrospectively reviewed all penetrating injuries at Tan Tock Seng Hospital, and identified and categorised all stab wound injuries as SI or IO. Basic demographic information, injury severity characteristics and outcome data were compared between these two groups. A review of all mortalities was performed, including recording the causes of death. RESULTS: Between 2005 and 2010, there were a total of 149 stab wound injuries, of which 24 (16.1%) were SI and 125 (83.9%) were IO injuries. Patients tended to be young (mean age 34.1 ± 14.2 years). The mean Injury Severity Score was significantly different between the SI and IO groups (8.8 ± 6.5 vs. 12.3 ± 8.1; p = 0.03). In both groups, the majority underwent an operative procedure (83.3% vs. 85.6%) and had an average hospital stay of four days. CONCLUSION: The study confirms our hypothesis that SI injuries tend to be less severe than IO injuries and are more likely to occur at home rather than at a public area. This finding may be useful in the triage of patients with stab wound injuries.

Serum estrogen receptor beta mediated bioactivity correlates with poor outcome in lung cancer patients.

OBJECTIVES: The role of estrogen signaling in lung cancer remains unresolved. We investigate the influence of serum estrogenic compounds and estrogen receptor (ERα and ERß) mediated bioactivity on lung cancer outcomes. MATERIALS AND METHODS: Serum samples were collected from 222 postmenopausal Chinese patients diagnosed with lung cancer in five Singapore hospitals. Levels of the estrogenic compounds estradiol and estrone were measured using liquid chromatography tandem mass spectrometry. Free estradiol levels were calculated based on sex hormone binding globulin levels. ERα- and ERß-mediated bioactivity in serum samples were analyzed using reporter gene bioassays in human cells. RESULTS AND CONCLUSION: High ERß-mediated bioactivity predicted poorer lung cancer survival (p=0.001) on multivariable Cox regression analysis with adjustment for age, stage of tumor, smoking status, body mass index and histology. In comparison, levels of estrogens and ERα-mediated bioactivity were not associated with prognosis. Compared to the lowest tertile of ERß-mediated bioactivity, patients in the middle and highest tertiles had HR (95%CI) 1.60 (1.10-2.33) and 1.93 (1.32-2.82) (p for trend=0.001) higher risk of death from lung cancer. Using Kaplan-Meier survival curves, patients with high ERß-mediated bioactivity correlated with poorer overall survival (p=0.033). ERß-mediated bioactivity did not differ in terms of age, use of hormone replacement therapy, smoking, stage of tumor or histological subtype. High ERß-mediated bioactivity levels in patients' serum were associated with poorer prognosis in lung cancer patients. Our findings suggest that that compound(s) other than endogenous estrogens may be exerting this ERß bioactivity and studies to identify these compounds or groups of compounds need to be performed. Furthermore, the measurement of ERß activity in sera could potentially serve as a prognostic marker to predict lung cancer survival, and selective blockage of ERß signaling may have a role in lung cancer therapy.

Ethnic disparities in trauma mortality outcomes.

BACKGROUND: Ethnic disparities in trauma mortality outcomes have been demonstrated in the United States according to the US National Trauma Data Bank. The aim of this study was to determine the effect of race/ethnicity on trauma mortality in Singapore. METHODS: This was a retrospective review of patients aged 18-64 years with an injury severity score (ISS) ≥ 9 in the Trauma Registry of Tan Tock Seng Hospital, a 1,300-bed trauma center in Singapore, from 2006 to 2010. Chinese, Malay, and Indian patients were compared with patients of other ethnic groups. Multiple logistic regression analyses determined differences in survival rates after adjusting for demographics, anatomic and physiologic ISS and revised trauma score, mechanism or type of injury. RESULTS: A total of 4,186 patients (66.4 % of the database) met the inclusion criteria. Most patients were male (76.3 %) and young (mean age 40 years). Using Chinese as the reference group, we found no statistically significant differences in unadjusted or adjusted mortality rates among the ethnic groups. Independent predictors of mortality included age [odds ratio (OR) 1.05, 95 % confidence interval (CI) 1.03-1.06, p < 0.0001], presence of severe head injury (OR 1.75, 95 % CI 1.13-2.69, p = 0.012), and increasing ISS (p < 0.0001). CONCLUSIONS: Ethnicity is not an independent predictor of trauma mortality outcomes in the Singapore population. Our findings contrast with those from the United States, where race/ethnicity (Black and Hispanic) remains a strong independent risk factor for trauma mortality. This study attests to the success of the Singapore health care/trauma system in delivering the same quality of care regardless of ethnicity.

Serum estrogen receptor bioactivity and breast cancer risk among postmenopausal women.

The estrogen levels of Asian women are different from those of Western women, and this could affect estrogen receptor (ER) bioactivity and breast cancer risk. We conducted a case-control study in 169 postmenopausal breast cancer cases and 426 matched controls nested within a population-based prospective cohort study, the Singapore Chinese Health Study, to evaluate the serum levels of estrogens and their receptor (ERα and ERß)-mediated estrogenic activities in relation to breast cancer risk. Breast cancer cases had higher levels of estrogens and ER-mediated bioactivities in baseline serum than the controls. Compared with those in the lowest quartile, women in the highest quartile for estrone (E1) or ERα-mediated bioactivity had increased breast cancer risk. After additional adjustment for ERß bioactivity, free estradiol, and E1 levels, serum ERα-mediated bioactivity remained associated with increased breast cancer risk. Compared with those in the lowest quartile, women in the highest quartile for ERα-mediated bioactivity had an odds ratio of 2.39 (95% CI=1.17-4.88; P for trend=0.016). Conversely, the positive association between E1 and cancer risk became null after adjustment for ERα-mediated bioactivity, suggesting that the effect of E1 could be mediated through ERα. Factor(s) contributing to increased ERα-mediated estrogenic bioactivity in serum and its role as a predictor for breast cancer risk need to be validated in future studies.

Serum free estradiol and estrogen receptor-α mediated activity are related to decreased incident hip fractures in older women.

There is paucity of data from Asian women on the association between serum estrogens and osteoporotic hip fracture risk. We conducted a case-control study nested within a population-based prospective cohort, The Singapore Chinese Health Study, to evaluate serum estrogens levels, ERα-mediated estrogenic activity and hip fracture risk in postmenopausal Asian women. Among 35,298 women who were recruited between 1993 and 1998, 15,410 women donated blood for research between 1999 and 2004. From this subcohort, we identified 140 cases who subsequently suffered hip fracture after blood donation, and 278 age-matched controls. Serum levels of total estrone, estradiol and sex hormone binding globulin levels were measured in a blinded fashion among cases and controls. ERα-mediated estrogenic activity of serum samples was quantified using a sensitive ERα-driven cell bioassay. Women with hip fracture had lower serum estrogens than control women. Compared to the lowest quintile, women in the highest quintile of free estradiol exhibited a statistically significant 57% reduction in risk of hip fracture (95% confidence interval (CI), 6-80%), with a dose-dependent relationship (p for trend=0.021). High levels of ERα-mediated estrogenic activity were also associated with decreased risk of hip fracture (p for trend=0.048). Overall, women with relatively high levels of both free estradiol and ERα-mediated estrogenic activity had a 55% reduction in hip fracture risk (95% CI, 17-76%) compared to women with low levels of both. High levels of free estradiol and ERα-mediated estrogen activity in sera were associated with reduced hip fracture risk in Chinese postmenopausal women.