- Dr. Mohamad Adam Bujang is a Research Officer at the Institute for Clinical Research (ICR), Ministry of Health, Malay... moreDr. Mohamad Adam Bujang is a Research Officer at the Institute for Clinical Research (ICR), Ministry of Health, Malaysia. Having received his Bachelor’s degree in Statistics from MARA University of Technology in 2004, Dr. Mohamad Adam undertook his postgraduate study, receiving his Master’s degree (MBA) in 2008, and then at the same university, receiving his PhD (Information Technology and Quantitative Sciences) in 2017. Currently he is working as a biostatistician and researcher in the Clinical Research Centre, Sarawak General Hospital. His ongoing research interests involve the research methodology such as questionnaire development, questionnaire validation, sampling techniques, sample size planning, and statistical analyses. He has completed many research projects with local and international publications. He is actively involved in research training, reviewer for number of peer-reviewed journals and also one of the former and active members in Malaysia Institute of Statistics (ISM) and Association of Clinical Registries Malaysia (ACRM).edit
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Introduction: Gestational diabetes (GDM) has significant maternal and foetal implications. screening allows active interventions which significantly improves pregnancy outcomes. Despite World Health Organization (WHO), FIGO and National... more
Introduction: Gestational diabetes (GDM) has significant maternal and foetal implications. screening allows active interventions which significantly improves pregnancy outcomes. Despite World Health Organization (WHO), FIGO and National Institute of clinical Excellence (NIcE) recommendations for universal screening especially among high risk population; Malaysia currently adopts a selective risk based screening for GDM. Objective: the objective is to audit the effectiveness of the current practice of selective risk based screening in detection of GDM in Malaysia. Methodology: this is a retrospective cohort study based on the National Obstetric Registry (NOR) which comprises of 14 major tertiary hospitals in Malaysia. the study period was from 1st January 2011 till 31st December 2012 and a total of 22,044 patients with GDM were analysed. Logistic regression analysis was used to calculate the crude odd ratio. Results: the incidence of GDM in Malaysia is 8.4%. Maternal age of ≥25, booking bMI ≥27kg/m2, booking weight ≥80kg and previous hypertension are non-significant risk of developing GDM in Malaysia. Parity 5 and more was only associated with an odds-ratio of 1.02 (95% confidence Interval: 0.90-1.17) as compared to parity below 5. the association of women with previous stillbirth with GDM was not significant. Conclusion: current risk based screening for GDM based on maternal age, booking bMI, weight and hypertension is inappropriate. An ideal screening tool should precede disease complications, which is the novel objective of screening. Universal screening for GDM in Malaysia may be a more accurate measure, especially with regards to reducing maternal and foetal complications.
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Research Interests: History and Suicide Rates
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Background: This study aimed to investigate the potential contribution of invalid skewed responses to invalid factor solution in the result from exploratory factor analysis. In the present study, Âthe invalid skewed response is defined... more
Background: This study aimed to investigate the potential contribution of invalid skewed responses to invalid factor solution in the result from exploratory factor analysis. In the present study, Âthe invalid skewed response is defined as when majority of respondents consistently rate only at one side which will eventually change the real or valid pattern of overall responses. Methods: A validation approach was conducted using a secondary data from a questionnaire validation study of an eight Likert scale, that has a very stable and strong factor solution. Eight sub samples were retrieved from the data to represent multiple sets of analyses with sample size based on rule of thumbs from 3:1 until 10:1. From each sub sample, proportion of dummy response for the extreme left (scale of 0), the middle scale (scale of 4) and the extreme right (scale of 7) were assigned randomly at 10%, 20% and 30% respectively. Results: The invalid consistent responses of a middle scale have very low impact towards the factor solution. The occurrence of the invalid skewed responses affected the factor solution. Majority of the factor solutions were still valid based on consistent responses with 10.0% only. However, the construct that was based on forcing into 4-factor solution had helped to produce the valid factor solution though some resulted in cross-loadings. All CronbachÂs alphas and minimum corrected item to total correlation were relatively strong for all factor solutions although some of the solutions were invalid. Conclusions: The skewed responses have the potential to change the ideal factor solution. Therefore, necessary steps need to be taken to avoid invalid skewed responses especially in self-administered survey. Therefore, the recommended sample size guideline for EFA with justifications is proposed.
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Background. The incidence of patients with end-stage renal disease (ESRD) requiring dialysis has been growing rapidly in Malaysia from 18 per million population (pmp) in 1993 to 231 pmp in 2013. Objective. To forecast the incidence and... more
Background. The incidence of patients with end-stage renal disease (ESRD) requiring dialysis has been growing rapidly in Malaysia from 18 per million population (pmp) in 1993 to 231 pmp in 2013. Objective. To forecast the incidence and prevalence of ESRD patients who will require dialysis treatment in Malaysia until 2040. Methodology. Univariate forecasting models using the number of new and current dialysis patients, by the Malaysian Dialysis and Transplant Registry from 1993 to 2013 were used. Four forecasting models were evaluated, and the model with the smallest error was selected for the prediction. Result. ARIMA (0, 2, 1) modeling with the lowest error was selected to predict both the incidence (RMSE = 135.50, MAPE = 2.85, and MAE = 87.71) and the prevalence (RMSE = 158.79, MAPE = 1.29, and MAE = 117.21) of dialysis patients. The estimated incidences of new dialysis patients in 2020 and 2040 are 10,208 and 19,418 cases, respectively, while the estimated prevalence is 51,269 an...
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Health-related quality of life (HRQOL) is one of the most important outcome measures to be assessed by medical research. This study aims to develop and validate an instrument called the “health-related quality of life with six domains”... more
Health-related quality of life (HRQOL) is one of the most important outcome measures to be assessed by medical research. This study aims to develop and validate an instrument called the “health-related quality of life with six domains” (HRQ-6D), which aims to measure an individual’s health-related quality of life within a 24 h period of time. This is a questionnaire development study involving five phases, which are (i) to explore the subject matter content for gaining a better understanding of the topic, (ii) to develop the questionnaire, (iii) to assess both its content validity and face validity, (iv) to conduct a pilot study, and finally, (v) to undertake a field testing of the questionnaire. For the field-testing phase, a cross-sectional study involving a self-administered survey for HRQ-6D items was conducted among healthcare workers with various health conditions. Exploratory factor analysis was initially applied to construct the major dimensions of the HRQ-6D. Confirmatory f...
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Sample size calculation based on a specified width of 95% confidence interval will offer researchers the freedom to set the level of accuracy of the statistics that they aim to achieve for a particular study. This paper provides a... more
Sample size calculation based on a specified width of 95% confidence interval will offer researchers the freedom to set the level of accuracy of the statistics that they aim to achieve for a particular study. This paper provides a description of the general conceptual context for performing sensitivity and specificity analysis. Subsequently, sample size tables for sensitivity and specificity analysis based on a specified 95% confidence interval width is then provided. Such recommendations for sample size planning are provided based on two different scenarios: one for a diagnostic purpose and another for a screening purpose. Further discussion on all the other relevant considerations for the determination of a minimum sample size requirement and on how to draft the sample size statement for performing sensitivity and specificity analysis are also provided.
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Research Interests: Pediatrics, China, Risk assessment, Medicine, Humans, and 15 moreChild, Female, Male, Infant, Developmental disabilities, Mandarin Chinese, Parents, Observer Variation, Reproducibility of Results, Risk Assessment, Cross Sectional Studies, Early Diagnosis, Logistic Models, Child preschool, and attitude to health
Non-communicable diseases (NCD) is a global health threat. the Chronic Care Model (CCM) was proven effective in improving NCD management and outcomes in developed countries. Evidence from developing countries including Malaysia is limited... more
Non-communicable diseases (NCD) is a global health threat. the Chronic Care Model (CCM) was proven effective in improving NCD management and outcomes in developed countries. Evidence from developing countries including Malaysia is limited and feasibility of CCM implementation has not been assessed. this study intends to assess the feasibility of public primary health care clinics (PHC) in providing care according to the CCM. A cross-sectional survey was conducted to assess the public PHC ability to implement the components of CCM. All public PHC with Family Medicine Specialist in Selangor and Kuala Lumpur were invited to participate. A site feasibility questionnaire was distributed to collect site investigator and clinic information as well as delivery of care for diabetes and hypertension. there were a total of 34 public PHC invited to participate with a response rate of 100%. there were 20 urban and 14 suburban clinics. the average number of patients seen per day ranged between 25...
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The effect of dialysis treatment is complex, with both clinical and socio-psychological effects. In this study, we aimed to assess the psychological status of this growing population of end-stage renal disease. Using the Short Form of... more
The effect of dialysis treatment is complex, with both clinical and socio-psychological effects. In this study, we aimed to assess the psychological status of this growing population of end-stage renal disease. Using the Short Form of Depression, Anxiety and Stress Scale (DASS21) questionnaire, we aimed (1) to measure the psychological states of hemodialysis (HD) or peritoneal dialysis (PD) subjects from 15 sites, (2) to compare DASS21 scores between HD and PD, and (3) to identify the associated demographic and medical factors of better psychological states. A total of 1,332 were eligible for analysis. Stress (48%) recorded the highest negative emotional states, followed by depression (37%) and anxiety (20%). By multivariate analysis, normal body mass index weight status, religion and absence of coronary artery disease were associated with lower score for depression, anxiety and stress, respectively. Tertiary education was associated with the lowest score in depression and anxiety, ...
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Background: The prognostic value of diastolic dysfunction estimates in clinical settings is not well established. We aimed to evaluate the impact of the 2016 American Society of Echocardiography and the European Association of... more
Background: The prognostic value of diastolic dysfunction estimates in clinical settings is not well established. We aimed to evaluate the impact of the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging recommendations on estimates of diastolic dysfunction and predicting cardiovascular outcomes in patients with diabetes and hypertension. Methods: In total, 111 patients with diabetes and hypertension without a known history of cardiovascular diseases were enrolled. All patients had preserved left ventricular ejection fraction on echocardiography at screening. Echocardiography was performed at baseline. The 2009 and 2016 algorithms were applied in diastolic function assessment. All patients were followed up for 1 year to assess clinical outcomes. Results: There were 65 (58.6%) female patients. The mean age was 59.86 ± 7.45 years, and the mean duration of diabetes was 10.5 ± 5.41 years. Fifty-five (50.5%) patients had left ventricular hype...
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INTRODUCTION A proper prioritisation system of emergency cases allows appropriate timing of surgery and efficient allocation of resources and staff expertise. The aim of this study was to determine the impact of colour coding... more
INTRODUCTION A proper prioritisation system of emergency cases allows appropriate timing of surgery and efficient allocation of resources and staff expertise. The aim of this study was to determine the impact of colour coding classification on Time-to- theatre (TTT) of patients in comparison with the normal practice. METHOD Categorisation was a surgical judgment call after thorough clinical assessment. There were 4 levels of urgency with their respective TTT; Red (2 hours), Yellow (8 hours), Green (24 hours), Blue (72 hours). Caesarean cases were excluded in colour coding due to pre - existing classification. The data for mean TTT was collected 4 weeks before the implementation (Stage 1), and another 4 weeks after implementation (Stage II). As there was a violation in the assumption for parametric test, Mann Whitney U test was used to compare the means between these two groups. Using logarithmic (Ln) transformation for TTT, Analysis of Covariance (ANCOVA) was conducted for multivari...
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Background: MLR and ANCOVA are common statistical techniques and are used for both experimental and non-experimental studies. However, both types of study designs may require different basis of sample size requirement. Therefore, this... more
Background: MLR and ANCOVA are common statistical techniques and are used for both experimental and non-experimental studies. However, both types of study designs may require different basis of sample size requirement. Therefore, this study aims to proposed sample size guidelines for MLR and ANCOVA for both experimental and non-experimental studies. Methods: We estimated the minimum sample sizes required for MLR and ANCOVA by using Power and Sample Size software (PASS) based on the pre-specified values of alpha, power and effect size (R 2 ). In addition, we also performed validation of the estimates using a real clinical data to evaluate how close the approximations of selected statistics which were derived from the samples were to the actual parameters in the targeted populations. All the coefficients, effect sizes and r-squared obtained from the sample were then compared with their respective parameters in the population. Results: Small minimum sample sizes required for performing...
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Analysis of patient data can be a complicated and challenging process, especially when the data involve many subjects and many variables. A patient registry is a database that organizes collecting the important set of data on a list of... more
Analysis of patient data can be a complicated and challenging process, especially when the data involve many subjects and many variables. A patient registry is a database that organizes collecting the important set of data on a list of identifiable individuals for a specific disease. This type of data usually has tons of data and hundreds of different variables. Thus, the approach to conducting research by using a patient registry database will be more complicated than the other types of dataset. Since the handling of patient registry data is a challenging task, the authors have come out with this book to become a guideline for the statisticians, medical officers and scientists for them to refer as a handbook whenever they need to use patient registry data for their research.
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Introduction: The aim of this study is to determine the most common organisms isolated in diabetic foot infection and the most utilised antibiotic regimes as the first line of treatment. Methods: This is a retrospective record review of... more
Introduction: The aim of this study is to determine the most common organisms isolated in diabetic foot infection and the most utilised antibiotic regimes as the first line of treatment. Methods: This is a retrospective record review of the National Orthopaedic Registry Malaysia among diabetes mellitus type 2 patients who had foot infections. All identified cases admitted to 18 government hospitals in Malaysia from the 1st January 2008 until the 31st December, 2009 were included in the study. Results: A total of 416 patients were included in the study. The most common organisms cultured were Proteus species (17.5%), Klebsiella species (17.1%) and Staphylococcus aureus (17.9%), while the most commonly used antibiotic was ampicillin/sulbactam (67.5%). None of the patients was appropriately treated with metronidazole, cefoperazone or fucidic acid. All patients were given appropriate antibiotics to treat Serratia infection. Conclusion: Significant number of patients with diabetic foot i...
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Correlation analysis is a common statistical analysis in various fields. The aim is usually to determine to what extent two numerical variables are correlated with each other. One of the issues that are important to be considered before... more
Correlation analysis is a common statistical analysis in various fields. The aim is usually to determine to what extent two numerical variables are correlated with each other. One of the issues that are important to be considered before conducting any correlation analysis is to plan for the sufficient sample size. This is to ensure, the results that to be derived from the analysis be able to reach a desired minimum correlation coefficient value with sufficient power and desired type I error or p-value. Sample size estimation for correlation analysis should be in line with the study objective. Researchers who are not statistician need simpler guideline to determine the sufficient sample size for correlation analysis. Therefore, this study aims to tabulate tables that show sample size calculation based on desired correlation coefficient, power and type 1 error (p-value) values. Moving towards that, simpler guidelines are proposed to estimate sufficient sample size requirements in diff...
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One of the determining factors for a successful research output is the design of the research itself. Thus, a researcher, a methodologist or an epidemiologist and a biostatistician may each have his/her own perspective of how to optimize... more
One of the determining factors for a successful research output is the design of the research itself. Thus, a researcher, a methodologist or an epidemiologist and a biostatistician may each have his/her own perspective of how to optimize the design of research, by playing an active role in both planning and conducting the research. Therefore, this e-book emphasizes the importance of the role of a biostatistician in managing and conducting research consultations mainly for research that revolves around the medical field.<br> <br> Successful biostatistics consultation requires a collection of technical and collaborative skills. The full spectrum of biostatistical consulting skills are rarely taught in training programs. However, by acquiring all the relevant skills for biostatistical consultation, one can continue to hone such skills by learning and gaining relevant experience throughout one's career.<br> <br> The discussion is divided into five sections: E...
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The importance of early recognition and treatment of sepsis and its effects on short-term survival outcome have long been recognized. Having reliable indicators and markers that would help prognosticate the survival of these patients is... more
The importance of early recognition and treatment of sepsis and its effects on short-term survival outcome have long been recognized. Having reliable indicators and markers that would help prognosticate the survival of these patients is invaluable and would subsequently assist in the course of effective dynamic triaging and goal directed management. To determine the prognosticative value of Shock Index (SI), taken upon arrival to the emergency department and after 2 hours of resuscitation on the shortterm outcome of severe sepsis and septic shock patients. This is a retrospective observational study involving 50 patients admitted to the University of Malaya Medical Centre between June 2009 and June 2010 who have been diagnosed with either severe sepsis or septic shock. Patients were identified retrospectively from the details recorded in the registration book of the resuscitation room. 50 patients were selected for this pilot study. The population comprised 19 males (38%) and 31 fem...
Research Interests: Adolescent, Humans, Septic Shock, Blood Pressure, Female, and 9 moreMale, Sepsis, Heart rate, Young Adult, ROC Curve, Aged, Middle Aged, Adult, and Prognosis
To develop a simple prediction model for the pre-screening of Retinopathy of Prematurity (ROP) among preterm babies. This was a prospective study. The test dataset (January 2007 until December 2010) was used to construct risk prediction... more
To develop a simple prediction model for the pre-screening of Retinopathy of Prematurity (ROP) among preterm babies. This was a prospective study. The test dataset (January 2007 until December 2010) was used to construct risk prediction models, and the validation dataset (January 2011 until March 2012) was used to validate the models developed from the test dataset. Two prediction models were produced using the test dataset based on logistic regression equations in which the development of ROP was used as the outcome. The sensitivity and specificity for model 1 [gestational age (GA), birth weight (BW), intraventricular haemorrhage (IVH) and respiratory distress syndrome (RDS)] was 82 % and 81.7%, respectively; for model 2, (GA and BW) the sensitivity and specificity were 80.5% and 80.3%, respectively. Model 2 was preferable, as it only required two predictors (GA and BW). Our prediction model can be used for early detection of ROP to avoid poor outcomes.
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Type 1 diabetes mellitus (DM) accounts for more than 90% of childhood and adolescent diabetes. Of the estimated 479,600 type 1 diabetic children worldwide, 24% were from the South-East Asian region and 6.4% from the Western Pacific... more
Type 1 diabetes mellitus (DM) accounts for more than 90% of childhood and adolescent diabetes. Of the estimated 479,600 type 1 diabetic children worldwide, 24% were from the South-East Asian region and 6.4% from the Western Pacific region.2–3 The annual incidence for childhood type 1 DM (0–14 year age group) ranged from 0.1 per 100,000 in China to 57.6 per 100,000 in Finland.3–5 The incidence of type 1 DM appeared to be low in the Western Pacific region with the exception of Australia and New Zealand. In Malaysia, type 1 DM was estimated to account for 69.2% of children and adolescents with diabetes.
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Objective: This study aims to measure the QoL and its associated factors among T2DM patients in Malaysia. Design: This is a cross sectional study and the sample was collected among T2DM patients who attended the Seremban 2 Health Clinic,... more
Objective: This study aims to measure the QoL and its associated factors among T2DM patients in Malaysia. Design: This is a cross sectional study and the sample was collected among T2DM patients who attended the Seremban 2 Health Clinic, Malaysia from December 2014 till March 2015. Materials and Methods: Data was collected via self-administered questionnaires that consisted of questions on patients' demographics, clinical variables and questions from the validated Malay version of the "Diabetic Quality of Life (DQoL)" questionnaire. Results: A total of 536 patients participated in the study. On a Likert scale of five points, the mean (SD) of the average scores for overall, satisfaction, impact and worry were 2.0 (0.5), 2.5 (0.9), 2.1 (0.5) and 1.2 (0.7) respectively. Age (p = 0.002), ethnicity (p = 0.044), status of diabetes treatment (p = 0.046), whether or not patients had attended a diabetes course (p = 0.025) and status of nephropathy (p = 0.032) were associated wi...
Research Interests: Psychology, Cognitive Science, Health Behavior, Medicine, Multidisciplinary, and 15 moreHumans, Female, Male, PLoS one, Health Status, Clinical Sciences, Aged, Day Care, Public Health and Preventive Medicine, Age Factors, Preventive, Neurosciences, Geriatrics and Gerontology, Community Health Centers, and Health services for the aged
Background and aims: To estimate sample size for Cohen’s kappa agreement test can be challenging especially when it is expected that the true marginal rating frequencies are not the same. This study aims to present the tables that display... more
Background and aims: To estimate sample size for Cohen’s kappa agreement test can be challenging especially when it is expected that the true marginal rating frequencies are not the same. This study aims to present the tables that display a minimum sample size determination for an agreement test when certain assumptions are hold. Method: We adopted the sample size formula provided by Flack and colleagues (1988) to calculate the minimum sample sizes required using PASS software. The power is pre-specified to be at least 80% and the alpha to be less than 0.05. The effect sizes were derived from several pre-specified estimates such as the pattern of the true marginal rating frequencies and the difference between the two kappa coefficients in the hypothesis testing. Results: When the true marginal rating frequencies are the same, the minimum sample size determination can range from 2 to 698 depending on the actual value of the effect size. When the true marginal rating frequencies are n...