Coronary artery calcification across ethnic groups in Singapore

<p><b>INTRODUCTION</b>In Singapore, the age-standardised event rates of myocardial infarction (MI) are 2- and 3-fold higher for Malays and Indians respectively compared to the Chinese. The objectives of this study were to determine the prevalence and quantity of coronary artery calcification (CAC) and non-calcified plaques across these 3 ethnic groups.</p><p><b>MATERIALS AND METHODS</b>This was a retrospective descriptive study. We identified 1041 patients (810 Chinese, 139 Malays, 92 Indians) without previous history of cardiovascular disease who underwent cardiac computed tomography for atypical chest pain evaluation. A cardiologist, who was blinded to the patients' clinical demographics, reviewed all scans. We retrospectively analysed all their case records.</p><p><b>RESULTS</b>Overall, Malays were most likely to be active smokers (P = 0.02), Indians had the highest prevalence of diabetes mellitus (P = 0.01) and Chinese had the highest mean age (P <0.0001). The overall prevalence of patients with non-calcified plaques as the only manifestation of sub-clinical coronary artery disease was 2.1%. There was no significant difference in the prevalence of CAC, mean CAC score or prevalence of non-calcified plaques among the 3 ethnic groups. Active smoking, age and hypertension were independent predictors of CAC. Non-calcified plaques were positively associated with male gender, age, dyslipidaemia and diabetes mellitus.</p><p><b>CONCLUSION</b>The higher MI rates in Malays and Indians in Singapore cannot be explained by any difference in CAC or non-calcified plaque. More research with prospective follow-up of larger patient populations is necessary to establish if ethnic-specific calibration of CAC measures is needed to adjust for differences among ethnic groups.</p>

Effectiveness of an algorithm in reducing the number of unnecessary ultrasound scans for deep vein thrombosis: an evaluation report

<p><b>INTRODUCTION</b>Patients with suspected deep vein thrombosis (DVT) pose a diagnostic dilemma to the Emergency Department (ED) clinician. This study aimed to implement a known algorithm incorporating the modified Wells criteria and D-dimer testing to guide the ED clinician, thus reducing unnecessary ultrasound scans (USS).</p><p><b>METHODS</b>Patients who presented to the ED between August 2008 and April 2009 with suspected DVT underwent Wells scoring. Those with scores < 2 were deemed unlikely to have DVT and underwent D-dimer testing first. Patients with scores ≥ 2 were regarded as likely to have DVT and underwent urgent USS. USS findings were tabulated as positive or negative/indeterminate for DVT. The latter group was followed up for one year to check whether DVT was missed during the initial USS.</p><p><b>RESULTS</b>75 patients presented with suspected DVT and underwent USS. Of these, 14 results were positive and 61 were negative. 37 patients had Wells scores < 2, with three (8.1%) having DVT. Another 38 patients had Wells scores ≥ 2, with 11 (28.9%) having DVT. D-dimer testing was performed on 27 of the 75 patients. Those with DVT had higher average values compared to those without DVT (1.305 vs. 0.595 µg/ml). The majority of patients with raised D-dimer values had cellulitis, although three also had DVT (with values ≥ 0.99 µg/ml).</p><p><b>CONCLUSION</b>We managed to reduce the number of unnecessary USS and increase the pick-up rate of DVT. A cut-off score ≥ 2 in our algorithm is suitable for use in the ED setting.</p>

The excess financial burden of multidrug resistance in severe gram-negative infections in Singaporean hospitals

<p><b>INTRODUCTION</b>Multidrug-resistant (MDR) Gram-negative healthcare-associated infections are prevalent in Singaporean hospitals. An accurate assessment of the socioeconomic impact of these infections is necessary in order to facilitate appropriate resource allocation, and to judge the costeffectiveness of targeted interventions.</p><p><b>MATERIALS AND METHODS</b>A retrospective cohort study involving inpatients with healthcare-associated Gram-negative bacteraemia at 2 large Singaporean hospitals was conducted to determine the hospitalisation costs attributed to multidrug resistance, and to elucidate factors affecting the financial impact of these infections. Data were obtained from hospital administrative, clinical and financial records, and analysed using a multivariate linear regression model.</p><p><b>RESULTS</b>There were 525 survivors of healthcare-associated Gram-negative bacteraemia in the study cohort, with 224 MDR cases. MDR bacteraemia, concomitant skin and soft tissue infection, higher APACHE II score, ICU stay, and appropriate definitive antibiotic therapy were independently associated with higher total hospitalisation costs, whereas higher Charlson comorbidity index and concomitant urinary tract infection were associated with lower costs. The excess hospitalisation costs attributed to MDR infection was $8638.58. In the study cohort, on average, 62.3% of the excess cost attributed to MDR infection was paid for by government subvention.</p><p><b>CONCLUSION</b>Multidrug resistance in healthcare-associated Gram-negative bacteraemia is associated with higher financial costs--a significant proportion of which are subsidised by public funding in the form of governmental subvention. More active interventions aimed at controlling antimicrobial resistance are warranted, and the results of our study also provide possible benchmarks against which the cost-effectiveness of such interventions can be assessed.</p>

Wash-out of hepatocellular carcinoma: quantitative region of interest analysis on CT

<p><b>INTRODUCTION</b>This study aims to determine if the quantitative method of region-of-interest (ROI) analysis of lesion attenuation on CT may be a useful adjunct to the conventional approach of diagnosis by visual assessment in assessing tracer wash-out in hepatocellular carcinomas.</p><p><b>MATERIALS AND METHODS</b>From a surgical database of 289 patients from 2 institutions, all patients with complete surgical, pathological and preoperative multiphasic CT scans available for review were selected. For each phase of scanning, HU readings of lesion obtained (Lesion(arterial), Lesion(PV) and Lesion(equilibrium)) were analysed using receiver operating curves (ROC) to determine the optimal method and cut-off value for quantitative assessment of tumour wash-out (Lesion(arterial - equilibrium), Lesion(PV - equilibrium) or Lesion(peak - equilibrium)).</p><p><b>RESULTS</b>Ninety-four patients with one lesion each met the inclusion criteria. The area under the curve (AUC) values for Lesion(arterial - equilibrium) (0.941) was higher than the AUC for Lesion(pv - equilibrium) (0.484) and for Lesion(peak - equilibrium) (0.667). Based on ROC analysis, a cut-off of 10HU value for Lesion(arterial - equilibrium) would yield sensitivity and specificity of 91.5% and 80.9%, respectively. ROI analysis detected 9/21 (42.9%) of lesions missed by visual analysis. Combined ROI and visual analysis yields a sensitivity of 82/94 (87.2%) compared to 73/94 (77.7%) for visual analysis alone.</p><p><b>CONCLUSION</b>Using a cut-off of 10 HU attenuation difference between the arterial and equilibrium phases is a simple and objective method that can be included as an adjunct to visual assessment to improve sensitivity for determining lesion wash-out on CT.</p>

Was it easy to use an Asthma Control Test (ACT) in different clinical practice settings in a tertiary hospital in Singapore?

<p><b>INTRODUCTION</b>The Asthma Control Test (ACT) is a 5-item self-administered tool designed to assess asthma control. It is said to be simple, easy and can be administered quickly by patients in the clinical practice setting. This stated benefit has yet to be demonstrated in our local clinical practice setting. The aim was to identify factors associated with difficulty in the administration of the ACT in different clinical practice settings in a tertiary hospital in Singapore.</p><p><b>MATERIALS AND METHODS</b>This is a prospective study performed from April to June 2008. All patients diagnosed with asthma and referred to an asthma nurse from the in-patient and out-patient clinical practice setting in Tan Tock Seng Hospital were enrolled.</p><p><b>RESULTS</b>Four hundred and thirty-four patients were asked to complete the ACT tool. In the univariate model, we found that age, clinical setting and medical history to be significantly associated with the completion of the ACT. The odds of completion decreased by a factor of 0.92 (95% CI, 0.89 to 0.94) for every year's increase in age, and this was statistically significant (P <0.001). Similarly, the odds ratio of completion for those with more than 3 medical conditions by history were 0.59 (95% CI, 0.48 to 0.71) as compared to those with less than 3 medical conditions by history, and this was also significant (P <0.001). In the multivariate model, we only found age to be an independent and significant factor. After adjusting for age, none of the other variables initially significant in the univariate model remained significant.</p><p><b>CONCLUSION</b>The results show that the ACT was simple and easy to be administered in younger-aged patients.</p>

A prospective cohort study on the impact of a modified Basic Military Training (mBMT) programme based on pre-enlistment fitness stratification amongst Asian military enlistees

<p><b>INTRODUCTION</b>This study objectively evaluates the effectiveness of a 6-week Preparatory Training Phase (PTP) programme prior to Basic Military Training (BMT) for less physically conditioned conscripts in the Singapore Armed Forces.</p><p><b>MATERIALS AND METHODS</b>We compared exercise test results of a group of less fi t recruits who underwent a 16-week modified-BMT (mBMT) programme (consisting of a 6-week PTP and 10-week BMT phase) with their 'fitter' counterparts enlisted in the traditional 10-week direct-intake BMT (dBMT) programme in this prospective cohort study consisting of 36 subjects. The main outcome measures included cardiopulmonary responses parameters (VO(2)max and V(O2AT)) with clinical exercise testing and distance run timings.</p><p><b>RESULTS</b>Although starting off at a lower baseline in terms of physical fitness [VO(2)max 1.73 +/- 0.27 L/min (mBMT group) vs 1.97 +/- 0.43 L/min (dBMT), P = 0.032; V(O2AT) 1.02 +/- 0.19 vs 1.14 +/- 0.32 L/min respectively, P = 0.147], the mBMT group had greater improvement in cardiopulmonary indices and physical performance profiles than the dBMT cohort as determined by cardiopulmonary exercise testing [VO(2)max 2.34 +/- 0.24 (mBMT) vs 2.36 +/- 0.36 L/min (dBMT), P = 0.085; V(O2AT) 1.22 +/- 0.17 vs 1.21 +/- 0.24 L/min respectively, P = 0.303] and 2.4 kilometres timed-run [mBMT group 816.1 sec (pre-BMT) vs 611.1 sec (post-BMT), dBMT group 703.8 sec vs 577.7 sec, respectively; overall P value 0.613] at the end of the training period. Initial mean difference in fitness between mBMT and dBMT groups on enlistment was negated upon graduation from BMT.</p><p><b>CONCLUSION</b>Pre-enlistment fitness stratification with training modification in a progressive albeit longer BMT programme for less-conditioned conscripts appears efficacious when measured by resultant physical fitness.</p>

Detection of internal carotid artery stenosis with duplex velocity criteria using receiver operating characteristic analysis

<p><b>INTRODUCTION</b>Duplex ultrasonography is an excellent non-invasive screening tool for carotid artery stenosis. The aim of this study was to evaluate optimal ultrasonographic criteria for determination of internal carotid artery stenosis with reference to digital subtraction angiography.</p><p><b>MATERIALS AND METHODS</b>From January 1995 to December 2003, 114 symptomatic patients underwent both duplex ultrasonography and angiography. Seven velocity criteria were compared with angiographic stenosis and receiver operating characteristic curves were used to determine the best cutoff for each criteria.</p><p><b>RESULTS</b>Internal carotid artery/common carotid artery systolic velocity ratios (PSV ICA/PSV CCA) and systolic internal carotid artery/diastolic common carotid artery ratios (PSV ICA/EDV CCA) were superior to other criteria for diagnosing internal carotid artery stenosis. For 50% stenosis, the best criterion of PSV ICA/PSV CCA was 1.5 [sensitivity 100%, specificity 85%, area under the curve (AUC) 99%], and the best criterion of PSV ICA/EDV CCA was 3.5 (sensitivity 100%, specificity 58%, AUC 99%). For 60% stenosis, the best criterion of PSV ICA/PSV CCA was 2.6 (sensitivity 100%, specificity 94%, AUC 99%), and the best criterion of PSV ICA/EDV CCA was 10.3 (sensitivity 100%, specificity 96%, AUC 99%). For 70% stenosis, the best criterion of PSV ICA/PSV CCA was 3.1 (sensitivity 100%, specificity 91%, AUC 99%), and the best criterion of PSV ICA/EDV CCA was 10.3 (sensitivity 100%, specificity 91%, AUC 99%).</p><p><b>CONCLUSION</b>Our study showed that velocity ratios are superior to other criteria for detecting carotid stenosis. Each laboratory needs to validate its own results.</p>

SARS in Singapore--predictors of disease severity

<p><b>INTRODUCTION</b>Severe acute respiratory syndrome (SARS) affected 8096 individuals in 29 countries, with 774 deaths. In Singapore, there were 238 cases of SARS with 33 deaths. A retrospective analysis was performed to identify predictors of poor outcome in patients with SARS locally.</p><p><b>MATERIALS AND METHODS</b>Clinical, laboratory and outcome data of 234 patients admitted to Tan Tock Seng Hospital and Singapore General Hospital were collected and analysed. Only data collected at the time of admission were used in the analysis for predictors of poor outcome. Adverse events were defined as admission to the intensive care unit or death.</p><p><b>RESULTS</b>Clinical (temperature, FiO2) and laboratory [leukocyte, lymphocyte, neutrophil, platelet, lactate dehydrogenase (LDH), albumin] trends in groups with and without an adversarial event were presented. Fifty patients experienced an adverse event. On univariate analysis, male gender, advanced age, presence of comorbidities, neutrophilia, lymphopaenia, hyponatraemia, hypoalbuminaemia, transaminitis and elevated LDH or C-reactive protein were found to be significant predictors. On multivariate analysis, predictors of poor outcome were increased age [odds ratio (OR) 1.73 for every 10-year increase; 95% CI, 1.35 to 2.21], neutrophilia (OR 1.06 for every 1 x 10(9)/L increase; 95% CI, 1.02 to 1.11) and high LDH (OR 1.17 for every 100 U/L increase; 95% CI, 1.02 to 1.34). None of the 12 paediatric patients had an adverse event.</p><p><b>CONCLUSION</b>Advanced age, neutrophilia and high LDH predict poor outcomes in patients with SARS.</p>

Evaluation of dementia: the case for neuroimaging all mild to moderate cases

<p><b>INTRODUCTION</b>The aim of this study was to assess the usefulness of 4 clinical prediction rules, the neuroimaging guidelines from the Canadian Consensus Conference on Dementia (CCCAD) and the modified Hachinski's Ischaemic Score (HIS) in identifying patients with suspected dementia who will benefit from neuroimaging.</p><p><b>MATERIALS AND METHODS</b>Two hundred and ten consecutive patients were referred to the memory clinic in a geriatric unit for the evaluation of possible dementia. Sensitivity, specificity and likelihood ratios (LR) were calculated for each of the prediction rules and the CCCAD guidelines, in terms of their ability to identify patients with significant lesions [defined firstly as space-occupying lesions (SOL) alone and secondly as SOL or strokes] on neuroimaging. Similar analyses were applied for the HIS in the detection of strokes.</p><p><b>RESULTS</b>When considering SOL alone, sensitivities ranged from 28.6% to 100% and specificities ranged from 21.7% to 88.4%. However, when strokes were included in the definition of significant lesions, sensitivities ranged from 16.2% to 79.0% and specificities ranged from 20.9% to 92.4%. The modified HIS had a similarly poor sensitivity and specificity (43.3% and 78.9% respectively). The LR for the clinical decision tools did not support the use of any particular instrument.</p><p><b>CONCLUSIONS</b>Clinical decision tools do not give satisfactory guidance for determining the need for neuroimaging patients with suspected dementia, when the detection of strokes, in addition to SOL, is regarded as important. We recommend therefore that neuroimaging be considered for all patients with suspected mild or moderate dementia in whom the potential benefits of any treatment outweigh the potential risks.</p>

Seroepidemiology of pertussis in the adult population of Singapore

<p><b>INTRODUCTION</b>Pertussis is a highly communicable, vaccine-preventable respiratory disease and a frequent but often underestimated cause of prolonged cough illness in adults. Protection after childhood vaccination is minimal after 10 years without boosting. The need for adult booster depends on the national epidemiology.</p><p><b>MATERIALS AND METHODS</b>We did a seroepidemiological survey amongst the adult population (aged 18 to 45 years) of Singapore. None had received pertussis booster vaccine in the preceding 10 years. We measured IgG antibodies to pertussis whole cell antigen.</p><p><b>RESULTS</b>Two hundred and seventy subjects with the median age of 30 years were enrolled. We found positive IgG antibody levels in 97% of the population. Seropositivity was not associated with age, gender or race.</p><p><b>CONCLUSION</b>The seroprevalence in adults was much higher than the previously documented seroprevalence of around 50% in the adolescent age group in Singapore. The increase is most likely due to natural infection with B. pertussis. Pertussis booster vaccine for adolescents/young adults in Singapore would be indicated.</p>