Chan Yiong Huak

Epidemiology of diabetic foot problems and predictive factors for limb loss

OBJECTIVES The aim of this study was to evaluate the epidemiology of diabetic foot problems (DFP) and predictive factors for major amputations (below- and above-knee). METHODS This is a prospective study of 202 patients treated in National University Hospital (NUH) during the period of January 2005 to May 2006. A protocol was designed for documentation including patient profile, type of DFP, presence of risk factors, comorbidities and complications, clinical presentation, investigations, treatment given, and final outcome. The predictors for limb loss were determined using univariate and stepwise logistic regression analysis. RESULTS One hundred ninety-two patients had Type 2 diabetes. Mean age of cohort was 60 years, with male to female ratio of 1:1. Incidence of DFP was significantly higher in Malays (P=.0015) and Indians (P=.036) and significantly lower in Chinese (P<.05). Of patients, 72.8% had poor endocrine control (GHb level >7%), and 42.1% of patients had sensory neuropathy based on 5.07 Semmes-Weinstein Monofilament test. Common DFP included gangrene (31.7%), infection (abscess, osteomyelitis) (28.7%), ulcer (27.7%), cellulitis (6.4%), necrotizing fasciitis (3.5%) and Charcots osteoarthropathy (2.0%). Surgery was performed in 74.8% of patients and major amputation in 27.2% of patients (below-knee in 20.3% and above-knee in 6.9%). CONCLUSIONS This is the first detailed prospective study evaluating predictive factors for major amputations in patients with DFP. Significant univariate predictive factors for limb loss were age above 60 years, stroke, ischaemic heart disease, nephropathy, peripheral vascular disease (PVD), sensory neuropathy, glycosylated haemoglobin level, Ankle Brachial Index (ABI) <0.8, gangrene, infection, and pathogens such as methicillin-resistant Streptococcus aureus (MRSA) and Staphylococcus aereus. Upon stepwise logistic regression analysis, only PVD and infection were significant.

A matched patient-sibling study on the usage of paracetamol and the subsequent development of allergy and asthma

A number of studies have suggested that intake of paracetamol during pregnancy and during the first months of life is associated with an increased risk of childhood asthma. We aimed to determine the association between paracetamol usage during pregnancy and the first 6 months of life, and childhood allergy (i.e. positive skin prick tests), allergic asthma, and asthma, using a matched patient‐sibling study comparing patients with allergic asthma with their healthy siblings without any symptoms of allergic diseases. Allergy in patients and their siblings was determined by skin prick tests. Children having at least one positive skin prick test were considered to be allergic. Intake of paracetamol was assessed by standardized, interviewer‐administered, questionnaire. Nineteen pairs of allergic asthma patients vs. non‐allergic siblings were compared to determine the risk factors for allergic asthma, while 15 pairs of allergic asthma patients vs. allergic siblings were compared to determine the risk factors for asthma. Moreover, 33 pairs of allergic asthma patients vs. non‐asthmatic siblings (with and without allergy) were compared to determine the risk factors for asthma. In addition, 17 allergic siblings (without asthma) were compared with 19 non‐allergic siblings (without asthma) to determine the risk factors for allergy. Usage of paracetamol during pregnancy was associated with allergic asthma (p = 0.03). Furthermore, usage of paracetamol between birth and 6 months of age, and between 4 and 6 months of age, was also found to be associated with non‐allergic asthma (p = 0.008 and p = 0.03 respectively). Usage of paracetamol during pregnancy and during the early months of life may play a role in the development of allergic and non‐allergic asthma in children. However, due to obvious ethical reasons, direct evidence for this association (i.e. a double‐blind, prospective study) is not available.

Assessment of Colour Differences in Silicone Hand and Digit Prostheses: Perceptible and Acceptable Thresholds for Fair and Dark Skin Shades

This study addresses the dilemma of initial clinical and social acceptance of a newly fabricated silicone prosthesis in relation to its colour match to the natural skin. This was achieved by derivation of specific colour difference thresholds defining perceptible and acceptable levels of colour sensitivity. Two separate sets of 10 fair and dark shade digit prosthesis samples were each fabricated with a stepped increase in colour difference (ΔE) against the baseline hand prosthesis. Ninety individuals with normal colour vision scores were selected as colour assessors. The colour difference of each prosthesis in the two series was evaluated visually against the baseline by the assessors, using defined scores. The thresholds for perceptible and acceptable colour difference determined in this study were ΔE = 0.8 and ΔE = 1.8 for the fair series and ΔE = 1.3 and ΔE = 2.6 for the dark series, respectively. The acceptable threshold values differed from the perceptible threshold values by ΔE = 1.0 for the fair-shade samples and ΔE = 1.3 for the dark-shade samples. This study demonstrated that subjective visual assessment is positively correlated with ΔE values computed from colorimetric measurements for both fair and dark-shade silicone samples (p<0.001). This results shows that human subjects with normal colour vision are capable of accurately assessing colour differences. These observations emphasize the importance of subjective feedback on colour by the patient, provided the latter has perfect colour-tested vision. The study also showed that human subjects were less sensitive to perceived colour differences in darker-shade than fairer-shade samples (p<0.001). This finding seems relevant in a clinical setting involving a multi-ethnic patient population.

Predictive factors for lower extremity amputations in diabetic foot infections

The objective of this study was to evaluate the epidemiology of diabetic foot infections (DFIs) and its predictive factors for lower extremity amputations. A prospective study of 100 patients with DFIs treated at the National University Hospital of Singapore were recruited in the study during the period of January 2005–June 2005. A protocol was designed to document patients demographics, type of DFI, presence of neuropathy and/or vasculopathy and its final outcome. Predictive factors for limb loss were determined using univariate and stepwise logistic regression analysis. The mean age of the study population was 59.8 years with a male to female ratio of about 1:1 and with a mean follow-up duration of about 24 months. All patients had type 2 diabetes mellitus. Common DFIs included abscess (32%), wet gangrene (29%), infected ulcers (19%), osteomyelitis (13%), necrotizing fasciitis (4%) and cellulitis (3%). Thirteen patients were treated conservatively, while surgical debridement or distal amputation was performed in 59 patients. Twenty-eight patients had major amputations (below or above knee) performed. Forty-eight percent had monomicrobial infections compared with 52% with polymicrobial infections. The most common pathogens found in all infections (both monomicrobial and polymicrobial) were Staphylococcus aureus (39.7%), Bacteroides fragilis (30.3%), Pseudomonas aeruginosa (26.0%) and Streptococcus agalactiae (21.0%). Significant univariate predictive factors for limb loss included age above 60 years, gangrene, ankle-brachial index (ABI) <0.8, monomicrobial infections, white blood cell (WBC) count ≥ 15.0×109/L, erythrocyte sedimentation rate ≥100 mm/hr, C-reactive protein ≥15.0 mg/dL, hemoglobin (Hb) ≤10.0g/dL and creatinine ≥150 µmol/L. Upon stepwise logistic regression, only gangrene, ABI <0.8, WBC ≥ 15.0×109/L and Hb ≤10.0g/dL were significant.

Morphologic quantification of the maxilla and the mandible with cone-beam computed tomography

INTRODUCTION The purpose of this pilot study was to use cone-beam computed tomography (CBCT) to determine the volumes of the maxilla and the mandible in subjects with skeletal Class I, Class II, and Class III malocclusions. Hypothesis 1 was that the volume (size) of a skeletal Class II maxilla is larger than those of Class I and Class III. Hypothesis 2 was that the volume of a skeletal Class III mandible is larger than those of Class I and Class II. METHODS Thirty women patients were classified into 3 groups according to their skeletal pattern: skeletal Class I (0 degrees < or =ANB <6 degrees ), Class II (ANB > or =6 degrees ) and Class III (ANB <0 degrees ). The volumes of the maxilla and the mandible were measured with CBCT. CB MercuRay (Hitachi Medico, Tokyo, Japan) and CB works software (CyberMed, Seoul, Korea) were used to process the images. RESULTS There was a trend that skeletal Class III subjects might have significantly greater mandibular volume compared with Class II subjects (P = 0.089). The ratios of maxilla-to-mandible volumes between the skeletal Class II and Class III groups were significantly different (P = 0.005). Differences were observed in the ratios of maxillary and mandibular volumes across the 3 groups. CONCLUSIONS Hypotheses 1 and 2 were rejected; there was no trend for Class III subjects to have larger mandibles (P = 0.089) compared with Class II subjects. The ratio of the maxilla and mandible volumes in skeletal Class III subjects was significantly larger (P = 0.005) compared with Class II subjects.

Motivation, study habits, and expectations of medical students in Singapore.

Objectives: To determine the motivation and incentives in education, learning experience and teaching techniques, and expectations about future careers among medical students from a multi-ethnic Asian country. Methods: Pre-validated questionnaire-based survey with stratified random sampling among medical students. The questionnaire combined qualitative responses with semi-quantitative measures of available alternatives. Results: The response rate was 83.1%. The most important factor for pursuing university study was ‘prospect of finding an interesting challenging job’ (rank 1–75%). Family made a significant contribution in decision making. Given the chance, a majority (67.2%) of respondents would prefer to study overseas. The main deterring factors were cost (67.7%), distance from home (28%), and local opportunity for post-graduation (23.4%). Despite their inclination of study overseas, the majority (73.9%) of the respondents indicated they were either very satisfied or satisfied with their current choice of university study. Only 20% of students were comfortable in asking questions in classroom as asking questions was deemed ‘too risky’ and ‘unnecessary to get better grades’. Students adopted strategies related to assessment and competition to monitor their study. Senior students reported university education as less relevant to their future careers as compared to junior students (p = 0.002). Conclusions: Students’ learning behaviour is determined by complex factors such as educational incentives, learning support, assessment and competition. Among several external factors, family, job prospects and expectations about the future play a critical role in education.

Point-of-Care Bedside Gas Analyzer: Limited Use of Venous pCO2 in Emergency Patients

BACKGROUND Because arterial punctures are more painful, venous blood gas analysis has been proposed as an alternative. OBJECTIVES To determine if venous pCO(2) can replace arterial pCO(2) in emergency patients using a bedside blood gas analyzer. METHODS This is a cross-sectional study. We recruited patients who were deemed by the attending Emergency Physicians to require arterial blood gas analysis to determine their ventilation or acid-base status. A venous and an arterial blood gas sample were drawn from the patient, temporally as close to each other as possible. Both samples were then analyzed using the same bedside blood gas analyzer immediately after collection. RESULTS There were 122 paired samples obtained. The strength of the association between arterial and venous pCO(2) is r = 0.838 (p = 0.001). The Bland-Altman bias plot methods for agreement show a mean difference of 3.3 mm Hg with two standard deviation limits of agreement being -17.4 to 23.9; 93.4% of the pCO(2) values fell within two standard deviation limits. Venous pCO(2) below 30 mm Hg had a 100% (95% confidence interval [CI] 90.5-100) sensitivity and 100% (95% CI 80.7-100) Negative predictive value to rule out hypercarbia, defined as arterial pCO(2) > 45 mm Hg. CONCLUSIONS There is significant variability in the arteriovenous difference of pCO(2) readings, hence, arterial punctures are still needed to specifically determine the arterial pCO(2).

Generalised convulsive status epilepticus in Singapore: Clinical outcomes and potential prognostic markers

PURPOSE To study the characteristics, outcomes and prognostic markers of convulsive status epilepticus (SE) in Singapore. METHODS 62 adult admissions to the National University Hospital Singapore from 2002 to 2005 were studied. Ethnicity, history of epilepsy, educational subnormality, neuroimaging, seizure duration, length of stay, Modified Rankin Scale (MRS) pre and post discharge, blood glucose, creatine kinase, potassium, white cell and platelet count were recorded. An MRS> or =3 at discharge was defined as a poor outcome. ROCs of significant variables were plotted to identify the best test cut-offs. RESULTS Mean age was 59.2 years (range 20-94). 75.9% patients had epilepsy. Mean length of stay was 14 days (range 1-75). Univariate analyses revealed age (p=0.01, OR 1.075, 95% CI 1.030-1.122), length of stay in ICU (p=0.03, OR 1.299, 95% CI 1.014-1.665) and hospital (p=0.014, OR 1.203, 95% CI 1.038-1.393) and hyperglycemia (p=0.045, OR 1.327, 95% CI 1.007-1.750) associated with poor outcome. Test cut-off values for prognostic markers were established: age> or =55 years (ROC 0.790, sensitivity 72.3, specificity 85.7, PPV9 4.4%, NPV 48.8%) and serum glucose> or =7 mmol/L (ROC 0.737, sensitivity 72.3, specificity 80.0, PPV 93.5%, NPV 36.4%). A discriminant model using these variables was then constructed with probability scores for poor outcome. DISCUSSION Age, hyperglycemia and length of stay in hospital influenced outcome from convulsive SE in the local population with hyperglycemia being a novel prognostic marker. Some prognostic markers cited in the literature differed, highlighting the possibility that these indicators may vary across population groups.

Emotional impact of 2004 Asian tsunami on Singapore medical relief workers

Objective: The aim was to study the emotional impact of the Asian tsunami on Singapore medical teams who responded in the immediate aftermath of the disaster. Method: Health‐care workers who returned from the medical missions were offered crisis intervention sessions (CISD). After the session, they were invited to participate in the study. Participation was strictly voluntary and their responses were anonymous. Twenty‐two (73.3%) health‐care workers participated in the crisis intervention sessions and completed the questionnaires. Questionnaires used were: demographics, General Health Questionnaire 28 (GHQ), Impact of Events Scale (IES), CISD feedback form. Results: None of the 22 responders had GHQ ⩾5. In all, 40% of the participants scored moderate (8.6–19) to high (>19.0) on the IES. The mean (SD) IES total score was 10.0 (11.0), range 0–42, with both the intrusive and avoidance scales contributing equally to the total score. There were two workers (9.1%, 95% CI 1.1–29.2) with IES >30. About 80% of the...

A multi-institutional survey on faculty development needs, priorities and preferences in medical education in an Asian medical school.

Abstract Background: Faculty development in medical education is crucial for maintaining academic vitality. The authors conducted a needs assessment survey in Singapore to determine the educational needs and priorities of clinical faculty. Methods: This study implemented a questionnaire-based, anonymous, multi-institutional survey with stratified random sampling. Each question was anchored with two statements on a 9-point scale. Respondents were asked to determine their current knowledge and the knowledge they would need in future. Results: The response rate was 81.9%. Overall, the participants’ current knowledge was rated either “modest” (scale 4-6) or “substantial” (scale 7-9), irrespective of teaching experience. Participants reported higher knowledge in areas related to teaching and modest knowledge in educational concepts and assessment. They reported a need for higher knowledge in most areas to function well as a teacher. Conclusion: The need for faculty development is universal and independent of teaching experience in this group. Teaching faculty from the institutes studied understood the need for improved knowledge in pedagogical knowledge.