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Search Results: 1 - 10 of 230 matches for " Arul Earnest "
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Exploring if day and time of admission is associated with average length of stay among inpatients from a tertiary hospital in Singapore: an analytic study based on routine admission data
Arul Earnest, Mark IC Chen, Eillyne Seow
BMC Health Services Research , 2006, DOI: 10.1186/1472-6963-6-6
Abstract: This was a historical cohort study based on all admissions from TTSH from 1st September 2003 to 31st August 2004. Data was extracted from routinely available computerized hospital information systems for analysis by episode of care. LOS for each episode of care was log-transformed before analysis, and a multivariate linear regression model was used to study if sex, age group, type of admission, admission source, day of week admitted, admission on a public holiday or eve of public holiday, admission on a weekend and admission time were associated with an increased LOS.In the multivariate analysis, sex, age group, type of admission, source of admission, admission on the eve of public holiday and weekends and time of day admitted were independently and significantly associated with LOS. Patients admitted on Friday, Saturday or Sunday stayed on average 0.3 days longer than those admitted on weekdays, after adjusting for potential confounders; those admitted on the eve of public holidays, and those admitted in the afternoons and after office hours also had a longer LOS (differences of 0.71, 1.14 and 0.65 days respectively).Cases admitted over a weekend, eve of holiday, in the afternoons, and after office hours, do have an increased LOS. Further research is needed to identify processes contributing to the above phenomenon.Optimising of length of stay is one approach to improving hospital performance, particular under funding systems that quantify outputs by the episode of care, as unnecessary inpatient bed-days constitute a significant component of per-episode costs. Casemix funding of inpatient services was introduced to Singapore in October 1999,[1] and it was based on the Australian National Diagnoses Related Group or AN-DRG system. The DRG system, which funds acute public sector hospitals such as Tan Tock Seng Hospital (TTSH), has given additional impetus towards finding factors which may be responsible for prolonging length of stay (LOS).Contribution to inappropriate
Predictors of failed attendances in a multi-specialty outpatient centre using electronic databases
Vernon J Lee, Arul Earnest, Mark I Chen, Bala Krishnan
BMC Health Services Research , 2005, DOI: 10.1186/1472-6963-5-51
Abstract: A retrospective study was conducted on outpatient clinic attendances at Tan Tock Seng Hospital, Singapore from 2000 to 2004. 22864 patients were randomly sampled for analysis. The outcome measure was failed outpatient appointments according to each patient's latest appointment.Failures comprised of 21% of all appointments and 39% when using the patients' latest appointment. Using odds ratios from the mutliple logistic regression analysis, age group (0.75 to 0.84 for groups above 40 years compared to below 20 years), race (1.48 for Malays, 1.61 for Indians compared to Chinese), days from scheduling to appointment (2.38 for more than 21 days compared to less than 7 days), previous failed appointments (1.79 for more than 60% failures and 4.38 for no previous appointments, compared with less than 20% failures), provision of cell phone number (0.10 for providing numbers compared to otherwise) and distance from hospital (1.14 for more than 14 km compared to less than 6 km) were significantly associated with failed appointments. The predicted probability model's diagnostic accuracy to predict failures is more than 80%.A few key variables have shown to adequately account for and predict failed appointments using existing electronic databases. These can be used to develop integrative technological solutions in the outpatient clinic.Failure to comply with outpatient medical appointments is a perennial problem, affecting costs, causing scheduling conflicts, and interrupting continuity of care. Failed appointments in different outpatient settings have ranged from 12% to 42% [1-7]. The resulting economic costs range from £65 per failed appointment in the United Kingdom in 1997 [2] to 3–14% of total outpatient clinic income in the United States [8]. This problem may be compounded if non-compliance with appointments is an indication of poorer clinical outcomes [9]. Most studies on failed appointments focused on the socio-economic and demographic factors that affect failures [1,10-
Using autoregressive integrated moving average (ARIMA) models to predict and monitor the number of beds occupied during a SARS outbreak in a tertiary hospital in Singapore
Arul Earnest, Mark I Chen, Donald Ng, Leo Sin
BMC Health Services Research , 2005, DOI: 10.1186/1472-6963-5-36
Abstract: This is a retrospective study design. Hospital admission and occupancy data for isolation beds was collected from Tan Tock Seng hospital for the period 14th March 2003 to 31st May 2003. The main outcome measure was daily number of isolation beds occupied by SARS patients. Among the covariates considered were daily number of people screened, daily number of people admitted (including observation, suspect and probable cases) and days from the most recent significant event discovery. We utilized the following strategy for the analysis. Firstly, we split the outbreak data into two. Data from 14th March to 21st April 2003 was used for model development. We used structural ARIMA models in an attempt to model the number of beds occupied. Estimation is via the maximum likelihood method using the Kalman filter. For the ARIMA model parameters, we considered the simplest parsimonious lowest order model.We found that the ARIMA (1,0,3) model was able to describe and predict the number of beds occupied during the SARS outbreak well. The mean absolute percentage error (MAPE) for the training set and validation set were 5.7% and 8.6% respectively, which we found was reasonable for use in the hospital setting. Furthermore, the model also provided three-day forecasts of the number of beds required. Total number of admissions and probable cases admitted on the previous day were also found to be independent prognostic factors of bed occupancy.ARIMA models provide useful tools for administrators and clinicians in planning for real-time bed capacity during an outbreak of an infectious disease such as SARS. The model could well be used in planning for bed-capacity during outbreaks of other infectious diseases as well.Early isolation of infectious cases has been shown to be a key component for the successful management of SARS outbreaks[1]. Due to the potential for nosocomial transmission[2-6], the imperfect ability of clinical criteria to distinguish cases of SARS at presentation[7], the
Cross-Reactivity against Naja sumatrana (Black Spitting Cobra) Envenoming from the Haffkine Antivenom in a Mouse Model
Gregory Cham,Francis Lim,Arul Earnest,Ponnampalam Gopalakrishnakone
ISRN Toxicology , 2013, DOI: 10.1155/2013/247645
Abstract: Naja sumatrana is the dominant cobra species in Malaysia, Singapore, Borneo, and Sumatra, and it does not have specific antivenom. The Haffkine antivenom has been advocated instead. This study aims to determine the efficacy of this antivenom against Naja sumatrana envenoming using a mouse model. Methods. Male Swiss albino mice were used. Intravenous LD50 was first determined separately for Naja naja and Naja sumatrana venom. ED50 was determined by preincubating antivenom with each venom at 2.5 LD50 before administering the mixture into the tail vein. Validation was carried out using a challenge test. Each mouse received 111?μg of Naja sumatrana venom intramuscularly followed by intraperitoneal administration of dilute Haffkine antivenom. Survival was recorded 24 hours after envenoming. Results. The LD50 of Naja naja venom was 78.13?μg, standard error (SE) 13.3?μg. The ED50 of the Haffkine antivenom against Naja naja venom was 45.9?mg, SE 7.5?mg. The LD50 and ED50 of Naja sumatrana venom were 55.5?μg, SE 12.0?μg; and 73.9?mg, SE 12.0?mg, respectively. The intra-peritoneal ED50 against 111?μg intramuscular Naja sumatrana venom was 136.95?mg, SE 36.74?mg. Conclusion. The Haffkine polyvalent antivenom exhibited cross-neutralisation against Naja sumatrana venom when used at a higher dose. 1. Introduction 1.1. Background and Importance Naja sumatrana, commonly known as the black spitting cobra or Equatorial spitting cobra, is the dominant cobra species in Peninsular Malaysia, Singapore, Borneo, and Sumatra [1]. It was estimated that the highest burden of snake bites exists in South Asia, Southeast Asia, and sub-Saharan Africa [2]. Cobra bites are common in Peninsular Malaysia and require significant medical intervention [3, 4]. However, snake bites are considered uncommon in largely urban Singapore [5, 6]. Unfortunately specific antivenom therapy against the Naja sumatrana does not exist. The Haffkine antivenom was arbitrarily advocated as an antivenom. It is an equine polyvalent antivenom raised against the Indian binocellate cobra (Naja naja), common krait (Bungarus caeruleus), Russell’s viper (Vipera russelli), and saw-scaled viper (Echis carinatus) [7]. However, these species of snakes are not normally found in Southeast Asia. The antivenom composition of the Haffkine was chosen for the treatment of black spitting cobra snake bites due to the empirical belief that cobras are originated from the Naja naja. These species are, however, considered to be separate now. It is unknown if the Haffkine product has any effective paraspecific activity against the
Comparing Statistical Models to Predict Dengue Fever Notifications
Arul Earnest,Say Beng Tan,Annelies Wilder-Smith,David Machin
Computational and Mathematical Methods in Medicine , 2012, DOI: 10.1155/2012/758674
Abstract: Dengue fever (DF) is a serious public health problem in many parts of the world, and, in the absence of a vaccine, disease surveillance and mosquito vector eradication are important in controlling the spread of the disease. DF is primarily transmitted by the female Aedes aegypti mosquito. We compared two statistical models that can be used in the surveillance and forecast of notifiable infectious diseases, namely, the Autoregressive Integrated Moving Average (ARIMA) model and the Knorr-Held two-component (K-H) model. The Mean Absolute Percentage Error (MAPE) was used to compare models. We developed the models using used data on DF notifications in Singapore from January 2001 till December 2006 and then validated the models with data from January 2007 till June 2008. The K-H model resulted in a slightly lower MAPE value of 17.21 as compared to the ARIMA model. We conclude that the models' performances are similar, but we found that the K-H model was relatively more difficult to fit in terms of the specification of the prior parameters and the relatively longer time taken to run the models.
Patterns of regional lymph node metastasis of nasopharyngeal carcinoma: A meta-analysis of clinical evidence
Francis CH Ho, Ivan WK Tham, Arul Earnest, Khai Lee, Jiade J Lu
BMC Cancer , 2012, DOI: 10.1186/1471-2407-12-98
Abstract: A literature search yielded an initial 411 original articles, and 13 studies with 2920 NPC cases staged via MRI were included in this analysis. The occurrence of nodal metastasis was calculated and analyzed according to the respective regional nodal levels.85% of NPC cases presented with lymphadenopathy. The most commonly involved regions include retropharyngeal (69%) and level II lymph nodes (70%). The overall probability of levels III, IV, and V nodal involvement are 45%, 11%, and 27%, respectively. Low-risk node groups included the supraclavicular, levels IA/IB and VI nodes, and parotid nodes with involvement rates at 3%, 0%, 3%, 0%, and 1%, respectively. Nodal metastases followed an orderly pattern and the probability of "skip" metastasis between levels varied between 0.5-7.9%.Lymph node metastasis in NPC follows a predictable and orderly pattern. The rarity of metastasis in certain nodal groups and "skip" metastasis suggest that reduced treatment volume is feasible in conformal radiotherapy for NPC.Nasopharyngeal carcinoma (NPC) is the most commonly diagnosed head and neck cancer in Southeast Asia, with a reported annual incidence of 30-80 per 105 population in endemic regions [1]. Like most other squamous cell carcinomas (SCC) of the head and neck primaries, lymphatic drainage of the nasopharynx is predominantly to the cervical lymph nodes. However, NPC has the highest preponderance for regional lymph node metastasis among head and neck SCC [2]. Radiation has been the mainstay of definitive treatment for NPC. The fields of radiation therapy for NPC traditionally encompass the primary disease and involved neck nodes, as well as the entire draining lymphatic regions to the lower neck. In a retrospective study reported by Lee et al, 57 (30%) of the 189 patients who did not receive elective neck irradiation subsequently developed cervical lymph node recurrence. However, none of the seven regionally treated patients relapsed [3]. Results from this and other similar
Clinical and epidemiological predictors of transmission in Severe Acute Respiratory Syndrome (SARS)
Mark IC Chen, Angela LP Chow, Arul Earnest, Hoe Leong, Yee Leo
BMC Infectious Diseases , 2006, DOI: 10.1186/1471-2334-6-151
Abstract: We used epidemiological and clinical data on probable SARS patients admitted to Tan Tock Seng Hospital. Using a case-control approach, index patients who had probable SARS who subsequently transmitted the disease to at least one other patient were analysed as "cases" against patients with no transmission as "controls", using multivariate logistic regression analysis.98 index patients were available for analysis (22 with transmission, 76 with no transmission). Covariates positively associated with transmission in univariate analysis at p < 0.05 included delay to isolation (Day 7 of illness or later), admission to a non-isolation facility, pre-existing chronic respiratory disease and immunosuppressive disease, need for oxygen, shortness of breath, vomiting, and higher lactate dehydrogenase levels and higher neutrophil counts. In the multivariate analysis, only three factors were significant: delay to isolation, admission to a non-isolation facility and higher lactate dehydrogenase levels of >650 IU/L (OR 6.4, 23.8 and 4.7 respectively).Clinical and epidemiological factors can help us to explain why transmission was observed in some instances but not in others.Severe Acute Respiratory Syndrome (SARS) was the first emerging infectious disease of the new century with epidemic potential. First recognized on 26 Feb 2003, SARS spread rapidly and resulted in 8098 reported cases and 774 deaths in close to 30 countries [1]. While there was no endemic transmission in the majority of these countries, explosive outbreaks were observed in China, Hong Kong, Taiwan, Canada, Vietnam and Singapore. Ongoing research points to an existing animal reservoir for the virus [2,3], and future epidemics may hence sporadically emerge from this source [4].A key feature in the epidemiology of SARS is the widespread variation in the number of secondary infections caused by each potentially infectious case. While multiple secondary infections were traced to single individuals in several super-sprea
Evaluating the effect of neighbourhood weight matrices on smoothing properties of Conditional Autoregressive (CAR) models
Arul Earnest, Geoff Morgan, Kerrie Mengersen, Louise Ryan, Richard Summerhayes, John Beard
International Journal of Health Geographics , 2007, DOI: 10.1186/1476-072x-6-54
Abstract: We created several neighbourhood weight matrices and applied them to a large dataset of births and birth defects in New South Wales (NSW), Australia within 198 Statistical Local Areas. Between the years 1995–2003, there were 17,595 geocoded birth defects and 770,638 geocoded birth records with available data. Spatio-temporal models were developed with data from 1995–2000 and their fit evaluated within the following time period: 2001–2003.We were able to create four adjacency-based weight matrices, seven distance-based weight matrices and one matrix based on similarity in terms of a key covariate (i.e. maternal age). In terms of agreement between observed and predicted relative risks, categorised in epidemiologically relevant groups, generally the distance-based matrices performed better than the adjacency-based neighbourhoods. In terms of recovering the underlying risk structure, the weight-7 model (smoothing by maternal-age 'Covariate model') was able to correctly classify 35/47 high-risk areas (sensitivity 74%) with a specificity of 47%, and the 'Gravity' model had sensitivity and specificity values of 74% and 39% respectively.We found considerable differences in the smoothing properties of the CAR model, depending on the type of neighbours specified. This in turn had an effect on the models' ability to recover the observed risk in an area. Prior to risk mapping or ecological modelling, an exploratory analysis of the neighbourhood weight matrix to guide the choice of a suitable weight matrix is recommended. Alternatively, the weight matrix can be chosen a priori based on decision-theoretic considerations including loss, cost and inferential aims.The Conditional Autoregressive (CAR) model is widely used in small-area ecological studies to map outcomes measured at some areal level and to examine associations with covariates. Most of these applications are in the field of disease mapping (See Elliott for a list of studies [1]). The advantages of using the CAR model i
Voriconazole or Amphotericin B as Primary Therapy Yields Distinct Early Serum Galactomannan Trends Related to Outcomes in Invasive Aspergillosis
Louis Yi Ann Chai, Bart Jan Kullberg, Arul Earnest, Elizabeth M. Johnson, Steven Teerenstra, Alieke G. Vonk, Haran T. Schlamm, Raoul Herbrecht, Mihai G. Netea, Peter F. Troke
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0090176
Abstract: An improved number of anti-fungal drugs are currently available for the treatment of invasive aspergillosis (IA). While serial galactomannan index (GMI) measurement can be used to monitor response to treatment, the extent to which different anti-fungal regimens can affect galactomannan levels is unknown. In 147 IA patients receiving either voriconazole (VCZ) or conventional amphotericin B (CAB) in a multicentre clinical trial, we performed post-hoc analyses of GMI trends in relation to outcomes. The generalized estimation equations approach was used to estimate changes in the effect size for GMI over time within patients. Patients who received VCZ primary therapy and had good treatment response 12 weeks later showed earlier decreases in GMI values at Week 1 and Week 2 (p = 0.001 and 0.046 respectively) as compared to patients who only received CAB. At end-of-randomized therapy (EORT), which was a pre-set secondary assessment point for all patients who switched from randomized primary (CAB or VCZ) to an alternative anti-fungal drug, treatment failure was associated with increasing GMI at Weeks 1 and 2 in CAB-primary treated patients (p = 0.022 and 0.046 respectively). These distinct trends highlight the variations in GMI kinetics with the use of different anti-fungal drugs and their implications in relation to IA treatment response.
Embedding the Schwarzschild Ideal Fluid Metric
Earnest Harrison
Physics , 2007,
Abstract: Certain semi-Riemannian metrics can be decomposed into a Riemannian part and an isochronal part. The properties of such metrics are particularly easy to visualize in a coordinate-free way, using isometric embedding. We present such an isochronal, isometric embedding of the well known Schwarzschild ideal fluid metric in an attempt to see what is happening when the pressure becomes singular.
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