Awang Bulgiba

Statistical Methods Used to Test for Agreement of Medical Instruments Measuring Continuous Variables in Method Comparison Studies: A Systematic Review

Background Accurate values are a must in medicine. An important parameter in determining the quality of a medical instrument is agreement with a gold standard. Various statistical methods have been used to test for agreement. Some of these methods have been shown to be inappropriate. This can result in misleading conclusions about the validity of an instrument. The Bland-Altman method is the most popular method judging by the many citations of the article proposing this method. However, the number of citations does not necessarily mean that this method has been applied in agreement research. No previous study has been conducted to look into this. This is the first systematic review to identify statistical methods used to test for agreement of medical instruments. The proportion of various statistical methods found in this review will also reflect the proportion of medical instruments that have been validated using those particular methods in current clinical practice. Methodology/Findings Five electronic databases were searched between 2007 and 2009 to look for agreement studies. A total of 3,260 titles were initially identified. Only 412 titles were potentially related, and finally 210 fitted the inclusion criteria. The Bland-Altman method is the most popular method with 178 (85%) studies having used this method, followed by the correlation coefficient (27%) and means comparison (18%). Some of the inappropriate methods highlighted by Altman and Bland since the 1980s are still in use. Conclusions This study finds that the Bland-Altman method is the most popular method used in agreement research. There are still inappropriate applications of statistical methods in some studies. It is important for a clinician or medical researcher to be aware of this issue because misleading conclusions from inappropriate analyses will jeopardize the quality of the evidence, which in turn will influence quality of care given to patients in the future.

Breast cancer in a multi-ethnic Asian setting: Results from the Singapore–Malaysia hospital-based breast cancer registry

Two hospital-based breast cancer databases (University Malaya Medical Center, Malaysia [n = 1513] and National University Hospital, Singapore [n = 2545]) were merged into a regional registry of breast cancer patients diagnosed between 1990 and 2007. A review of the data found 51% of patients diagnosed before the age of 50 years. and 72% percent of the women were Chinese followed by Malays (16%), Indians (8%), and other races (4%). Median tumor size at presentation was 26 mm and about 25% of patients presented with TNM stage III or IV disease. Most tumors were of ductal histology (87%). Fifty-seven percent of tumors were estrogen receptor positive and 40% were poorly differentiated. Of those patients who had surgery, 70% had mastectomy while 30% had breast conserving surgery. Overall, chemotherapy was administered to 56% of patients and hormonal treatment to 60%. Five-year overall survival was 82.5% in patients with TNM stage 0 to stage II cancer, and 30.2% in those with later stages.

High prevalence of vitamin D insufficiency and its association with obesity and metabolic syndrome among Malay adults in Kuala Lumpur, Malaysia

BackgroundVitamin D status, as indicated by 25-hydroxyvitamin D is inversely associated with adiposity, glucose homeostasis, lipid profiles, and blood pressure along with its classic role in calcium homeostasis and bone metabolism. It is also shown to be inversely associated with metabolic syndrome and cardiovascular diseases in western populations. However, evidence from the Asian population is limited. Therefore, we aim to study the prevalence of vitamin D insufficiency (< 50 nmol/L) and the association of 25-hydroxyvitamin D with metabolic risk factors among an existing Malay cohort in Kuala Lumpur.MethodsThis is an analytical cross sectional study. A total of 380 subjects were sampled and their vitamins D status (25-hydroxyvitamin D), fasting blood glucose, full lipid profile were assessed using venous blood. Systolic and diastolic blood pressure, weight, height and waist circumference were measured following standard protocols. Socio-demographic data such as sex, age, smoking status etc were also collected. Data was analysed using t-test, chi-square test, General Linear Model and multiple logistic regression.ResultsFemales made up 58% of the sample. The mean age of respondents was 48.5 (SD 5.2) years. Females had significantly lower mean Vitamin D levels (36.2; 95% CI: 34.5, 38.0 nmol/L) compared to males (56.2; 95% CI: 53.2, 59.2 nmol/L). Approximately 41% and 87% of males and females respectively had insufficient (< 50 nmol/L) levels of 25-hydroxyvitamin D (p < 0.001). The prevalence of Metabolic Syndrome for the whole sample was 38.4 (95% CI: 33.5, 43.3)%. In the multivariate model (adjusted for age, sex, abdominal obesity, HDL-cholesterol, diastolic blood pressure), insufficient Vitamin D status was significantly associated with 1-year age increments (OR: 0.93; 95% CI: 0.88, 0.98), being female (OR: 8.68; 95% CI: 5.08, 14.83) and abdominal obesity (OR: 2.57; 95% CI: 1.51, 4.39). Respondents with insufficient vitamin D were found to have higher odds of having Metabolic Syndrome (OR: 1.73; 95% CI: 1.02, 2.92) after adjusting for age and sex.ConclusionsOur results highlight the high prevalence of vitamin D insufficiency among Malay adults in Kuala Lumpur. Vitamin D insufficiency is independently associated with younger age, female sex and greater abdominal obesity. Vitamin D insufficiency is also associated with Metabolic Syndrome.

Prevalence and correlates of physical disability and functional limitation among community dwelling older people in rural Malaysia, a middle income country

BackgroundThe prevalence and correlates of physical disability and functional limitation among older people have been studied in many developed countries but not in a middle income country such as Malaysia. The present study investigated the epidemiology of physical disability and functional limitation among older people in Malaysia and compares findings to other countries.MethodsA population-based cross sectional study was conducted in Alor Gajah, Malacca. Seven hundred and sixty five older people aged 60 years and above underwent tests of functional limitation (Tinetti Performance Oriented Mobility Assessment Tool). Data were also collected for self reported activities of daily living (ADL) using the Barthel Index (ten items). To compare prevalence with other studies, ADL disability was also defined using six basic ADLs (eating, bathing, dressing, transferring, toileting and walking) and five basic ADLs (eating, bathing, dressing, transferring and toileting).ResultsTen, six and five basic ADL disability was reported by 24.7% (95% CI 21.6-27.9), 14.4% (95% CI 11.9-17.2) and 10.6% (95% CI 8.5-13.1), respectively. Functional limitation was found in 19.5% (95% CI 16.8-22.5) of participants. Variables independently associated with 10 item ADL disability physical disability, were advanced age (≥ 75 years: prevalence ratio (PR) 7.9; 95% CI 4.8-12.9), presence of diabetes (PR 1.8; 95% CI 1.4-2.3), stroke (PR 1.5; 95% CI 1.1-2.2), depressive symptomology (PR 1.3; 95% CI 1.1-1.8) and visual impairment (blind: PR 2.0; 95% CI 1.1-3.6). Advancing age (≥ 75 years: PR 3.0; 95% CI 1.7-5.2) being female (PR 2.7; 95% CI 1.2-6.1), presence of arthritis (PR 1.6; 95% CI 1.2-2.1) and depressive symptomology (PR 2.0; 95% CI 1.5-2.7) were significantly associated with functional limitation.ConclusionsThe prevalence of physical disability and functional limitation among older Malaysians appears to be much higher than in developed countries but is comparable to developing countries. Associations with socio-demographic and other health related variables were consistent with other studies.

Ethnic Differences in Survival after Breast Cancer in South East Asia

Background The burden of breast cancer in Asia is escalating. We evaluated the impact of ethnicity on survival after breast cancer in the multi-ethnic region of South East Asia. Methodology/Principal Findings Using the Singapore-Malaysia hospital-based breast cancer registry, we analyzed the association between ethnicity and mortality following breast cancer in 5,264 patients diagnosed between 1990 and 2007 (Chinese: 71.6%, Malay: 18.4%, Indian: 10.0%). We compared survival rates between ethnic groups and calculated adjusted hazard ratios (HR) to estimate the independent effect of ethnicity on survival. Malays (n = 968) presented at a significantly younger age, with larger tumors, and at later stages than the Chinese and Indians. Malays were also more likely to have axillary lymph node metastasis at similar tumor sizes and to have hormone receptor negative and poorly differentiated tumors. Five year overall survival was highest in the Chinese women (75.8%; 95%CI: 74.4%–77.3%) followed by Indians (68.0%; 95%CI: 63.8%–72.2%), and Malays (58.5%; 95%CI: 55.2%–61.7%). Compared to the Chinese, Malay ethnicity was associated with significantly higher risk of all-cause mortality (HR: 1.34; 95%CI: 1.19–1.51), independent of age, stage, tumor characteristics and treatment. Indian ethnicity was not significantly associated with risk of mortality after breast cancer compared to the Chinese (HR: 1.14; 95%CI: 0.98–1.34). Conclusion In South East Asia, Malay ethnicity is independently associated with poorer survival after breast cancer. Research into underlying reasons, potentially including variations in tumor biology, psychosocial factors, treatment responsiveness and lifestyle after diagnosis, is warranted.

Impairment of psychomotor responses after conscious sedation in cirrhotic patients undergoing therapeutic upper GI endoscopy

OBJECTIVES:The aim of this study was to determine whether the number connection test (NCT) times of a group of cirrhotic patients without clinically overt hepatic encephalopathy and a group of healthy patients without liver disease who were undergoing endoscopy were prolonged after sedation with short acting i.v. benzodiazepines.METHODS:All patients were administered the NCT in a standard fashion for 30 min before sedation for an upper GI endoscopy and then 2 h after sedation postprocedure. Two NCTs were carried out before and 2 h after sedation, and the mean of the tests pre- and postsedation calculated. Based on the upper limit of the 95% CI of the presedation NCT of patients without liver disease as the cut-off level for hepatic encephalopathy, the proportion of cirrhotic patients with subclinical encephalopathy before and after sedation were also determined.RESULTS:A total of 61 consecutive cirrhotic patients who underwent therapeutic upper GI endoscopy completed the study. The mean presedation NCT time was 43.5 s (95% CI = 39.0–48.1 s) and the mean postsedation NCT time 60.0 s (95% CI = 50.7–69.3 s). The difference between the mean pre- and postsedation NCT times was 16.4 s (95% CI = 9.8–23.1 s; p < 0.001). A total of 38 consecutive patients without clinical or biochemical evidence of liver disease who presented for upper GI endoscopy completed the NCT as described for the group of cirrhotic patients. The mean (± SD) baseline NCT time was 34.7 ± 7.9 s (95% CI = 32.1–37.2 s), whereas the mean postsedation NCT time was 33.7 ± 8.5 s (95% CI = 30.9–36.5 s). This difference was not statistically significant (p = 0.177). Using the upper limit of the 95% CI of the mean (37.4 s) of the presedation time in the patients without liver disease as the cut-off between normal and encephalopathy, the number of cirrhotic patients with abnormal presedation NCT times was 33 patients (54.1%), and this number rose to 46 patients (75.4%) after sedation with midazolam. This increase in proportion of cirrhotic patients with prolonged NCT time was statistically significant (p < 0.001).CONCLUSIONS:Sedation with i.v. midazolam prolongs NCT times in cirrhotic patients but not in healthy individuals without liver disease. The proportion of patients with prolonged NCT times increased in patients with cirrhosis following sedation, whereas this did not occur in those without liver disease.

The modified NCEP ATP III criteria maybe better than the IDF criteria in diagnosing Metabolic Syndrome among Malays in Kuala Lumpur

BackgroundMetabolic Syndrome is associated with increased risk for type 2 diabetes and cardiovascular diseases. However, different diagnostic criteria have been recommended by different expert groups. In Malaysia, there is a lack of research comparing these different diagnostic criteria. Therefore, it is our aim to study the concordance between the IDF and the modified NCEP ATP III definitions of Metabolic Syndrome among a Malay cohort in Kuala Lumpur; and to demonstrate if all participants have the same cardiometabolic risks.MethodsThis was an analytical cross sectional study. Ethics approval was obtained and informed consent was given by all participants. Anthropometric measurements, blood pressure, fasting blood glucose and lipid profile were taken following standard protocols.ResultsMetabolic Syndrome was diagnosed in 41.4% and 38.2% participants using the modified NCEP and IDF criteria respectively. Among those diagnosed with Metabolic Syndrome by modified NCEP, 7.6% were missed by the IDF criteria. Participants diagnosed by the modified NCEP criteria had lower BMI and waist circumference but had higher cardiometabolic risks than those diagnosed with both criteria. Their blood pressure, glucose, total cholesterol and triglyceride were more adverse than the IDF group. This demonstrated that central obesity may not be a prerequisite for the development of increased cardiometabolic risks within this Malay cohort.ConclusionMetabolic syndrome is common in this Malay cohort regardless of the criterion used. The modified NCEP ATP III criteria may be more suitable in diagnosis of metabolic syndrome for this Malay cohort.

Ethnic Differences in the Prevalence of Metabolic Syndrome: Results from a Multi-Ethnic Population-Based Survey in Malaysia

Introduction The prevalence of metabolic syndrome is increasing disproportionately among the different ethnicities in Asia compared to the rest of the world. This study aims to determine the differences in the prevalence of metabolic syndrome across ethnicities in Malaysia, a multi-ethnic country. Methods In 2004, we conducted a national cross-sectional population-based study using a stratified two-stage cluster sampling design (N = 17,211). Metabolic syndrome was defined according to the International Diabetes Federation/National Heart, Lung and Blood Institute/American Heart Association (IDF/NHLBI/AHA-2009) criteria. Multivariate models were used to study the independent association between ethnicity and the prevalence of the metabolic syndrome. Results The overall mean age was 36.9 years, and 50.0% participants were female. The ethnic distribution was 57.0% Malay, 28.5% Chinese, 8.9% Indian and 5.0% Indigenous Sarawakians. The overall prevalence of the metabolic syndrome was 27.5%, with a prevalence of central obesity, raised triglycerides, low high density lipoprotein cholesterol, raised blood pressure and raised fasting glucose of 36.9%, 29.3%, 37.2%, 38.0% and 29.1%, respectively. Among those <40 years, the adjusted prevalence ratios for metabolic syndrome for ethnic Chinese, Indians, and Indigenous Sarawakians compared to ethnic Malay were 0.81 (95% CI 0.67 to 0.96), 1.42 (95% CI 1.19 to 1.69) and 1.37 (95% CI 1.08 to 1.73), respectively. Among those aged ≥40 years, the corresponding prevalence ratios were 0.86 (95% CI 0.79 to 0.92), 1.25 (95% CI 1.15 to 1.36), and 0.94 (95% CI 0.80, 1.11). The P-value for the interaction of ethnicity by age was 0.001. Conclusions The overall prevalence of metabolic syndrome in Malaysia was high, with marked differences across ethnicities. Ethnic Chinese had the lowest prevalence of metabolic syndrome, while ethnic Indians had the highest. Indigenous Sarawakians showed a marked increase in metabolic syndrome at young ages.

The effectiveness of a life style modification and peer support home blood pressure monitoring in control of hypertension: protocol for a cluster randomized controlled trial

BackgroundDeath rates due to hypertension in low and middle income countries are higher compared to high income countries. The present study is designed to combine life style modification and home blood pressure monitoring for control of hypertension in the context of low and middle income countries.MethodsThe study is a two armed, parallel group, un-blinded, cluster randomized controlled trial undertaken within lower income areas in Kuala Lumpur. Two housing complexes will be assigned to the intervention group and the other two housing complexes will be allocated in the control group. Based on power analysis, 320 participants will be recruited. The participants in the intervention group (n = 160) will undergo three main components in the intervention which are the peer support for home blood pressure monitoring, face to face health coaching on healthy diet and demonstration and training for indoor home based exercise activities while the control group will receive a pamphlet containing information on hypertension. The primary outcomes are systolic and diastolic blood pressure. Secondary outcome measures include practice of self-blood pressure monitoring, dietary intake, level of physical activity and physical fitness.DiscussionThe present study will evaluate the effect of lifestyle modification and peer support home blood pressure monitoring on blood pressure control, during a 6 month intervention period. Moreover, the study aims to assess whether these effects can be sustainable more than six months after the intervention has ended.

Towards an effective control programme of soil-transmitted helminth infections among Orang Asli in rural Malaysia. Part 1: prevalence and associated key factors.

BackgroundDespite the continuous efforts to improve the quality of life of Orang Asli (Aborigines) communities, these communities are still plagued with a wide range of health problems including parasitic infections. The first part of this study aimed at determining the prevalence of soil-transmitted helminth (STH) infections and identifying their associated factors among rural Orang Asli children.MethodsA cross-sectional study was carried out among 484 Orang Asli children aged ≤ 15 years (235 females and 249 males) belonging to 215 households from 13 villages in Lipis district, Pahang, Malaysia. Faecal samples were collected and examined by using formalin-ether sedimentation, Kato Katz and Harada Mori techniques. Demographic, socioeconomic, environmental and behavioural information were collected by using a pre-tested questionnaire.ResultsOverall, 78.1% of the children were found to be infected with one or more STH species. The prevalence of trichuriasis, ascariasis and hookworm infections were 71.7%, 37.4% and 17.6%, respectively. Almost all, three quarters and one fifth of trichuriasis, ascariasis and hookworm infections, respectively, were of moderate-to-heavy intensities. Multiple logistic regression analysis showed that age of ≥ 6 years (school-age), using unsafe water supply as a source for drinking water, absence of a toilet in the house, large family size (≥ 7 members), not washing hands before eating, and not washing hands after defecation were the key factors significantly associated with STH among these children.ConclusionThis study reveals an alarmingly high prevalence of STH among Orang Asli children and clearly brings out an urgent need to implement school-based de-worming programmes and other control measures like providing a proper sanitation, as well as a treated drinking water supply and proper health education regarding good personal hygiene practices. Such an integrated control program will help significantly in reducing the prevalence and intensity of STH in Orang Asli communities.