CLINICAL TRIALS CTR

Researcher : Ansari MT

List of Research Outputs

 

Ansari M.T., Mahmood M.T. and Karlberg J.P.E., The association between seated immobility and local lower-limb venous coagulability in healthy adult volunteers: a simulation of prolonged travel immobility, Blood Coagulation and Fibrinolysis. 2006, 17 (5): 335-341.

 

Researcher : Fong DYT

Project Title:

Use of multiple imputation on linear mixed model and generalized estimating equations for longitudinal data analysis: a simulation study

Investigator(s):

Fong DYT, Lam KSL

Department:

Nursing Studies

Source(s) of Funding:

Small Project Funding

Start Date:

11/2005

Completion Date:

10/2006

 

Abstract:

Purpose of the proposed project: 1. To assess the performance of the mixed effects model and generalized estimating equations with and without using multiple imputation in estimating treatment effects on a continuous outcome at different time epochs. 2. To determine whether multiple imputation adds advantage to the use of mixed effects model or generalized estimating equations. Key issues and problems: 1. Missing values are frequent in clinical trials when study subjects are measured longitudinally due to many reasons, including dropouts, non-compliance, and adverse events. Common methods of longitudinal data analysis that are consistent to the intention-to-treat principle are the mixed effects model (MEM) and the generalized estimating equation (GEE) (Goldstein et al., 2002; Chan et al., 2005; Edwards, 2000; Wagner et al., 2005; Dahmen & Ziegler, 2004). Alternatively, multiple imputation (MI) emerged as a method to facilitate the use of methods that do not accommodate missing values. There has recently been an interest in examining the use of imputation methods on MEM and GEE. Several studies examined the use of GEE with and without MI on real datasets. However, it is still unclear about the performance of using MI together with MEM or GEE in a clinical trial setting when the objective is to determine the treatment effect at specific time epochs. 2. According to Rubin (1976), missing value mechanism can be classified as missing completely at random (MCAR) when the probability of having a missing value does not depend on the observed values nor the missing values had they were observed, missing at random (MAR) when the probability depends on the observed values only, and missing not at random (MNAR) when the probability depends on the missing values had they were observed. There has been no report of simulation results on the performance of using MI on MEM and GEE when missing values are missing not at random. References: 1. Rubin D. Inference and Missing Data. Biometrika 1976; 63(3):581-590. 2. Goldstein H, Browne W, Rasbash J. Multilevel modelling of medical data. Statistics in Medicine 2002; 21(21):3291-3315. 3. Chan YM, Lee PWH, Fong DYT, Fung ASM, Wu LYF, Choi AYY, Ng TY, Wong LC, Ngan HYS. The effect of psychosocial intervention in women with gynecological malignancy: A randomized controlled trial and a staff-in-service training programme. To appear in Journal of Clinical Oncology 2005. 4. Edwards LJ. Modern statistical techniques for the analysis of longitudinal data in biomedical research. Pediatric Pulmonology 2000; 30(4):330-344. 5. Wagner AK, Fabio A, Puccio AM, Hirschberg R, Li W, Zafonte RD, Marion DW. Gender associations with cerebrospinal fluid glutamate and lactate/pyruvate levels after severe traumatic brain injury. Critical Care Medicine 2005; 33(2):407-413. 6. Dahmen G, Ziegler A. Generalized estimating equations in controlled clinical trials: Hypotheses testing. Biometrical Journal 2004; 46(2):214-232.

 

Project Title:

Cost and clinical effectiveness of the Hong Kong scoliosis

Investigator(s):

Fong DYT, Cheung KMC, Luk KDK, Yip PSF

Department:

Nursing Studies

Source(s) of Funding:

Public Policy Research

Start Date:

04/2006

 

Abstract:

To estimate the cost of the scoliosis screening programme in Hong Kong; to examine the clinical effectiveness of the screening programme in terms of its efficacy and referral rates; to study the epidemiology of scoliosis in Hong Kong; to examine if a more discriminative screening program can be performed on the at risk age group a more selective group of children; to study the outcome of screened cases, the cost of subsequent follow up and treatment.

 

Researcher : Huang J

Project Title:

Hepatitis B or Hepatitis C viral infection and genotypes - which subgroup is more prone to the development of hepatocellular carcinoma? A systematic review

Investigator(s):

Huang J, Wong BCY, Lai CL, Yuen RMF

Department:

Clinical Trials Ctr

Source(s) of Funding:

Health and Health Services Research Fund - Full Grants

Start Date:

01/2004

 

Abstract:

To identify which subgroups of population infected with HBV/HCV are at higher risk for developing hepatocellular carcinoma (HCC).

 

Researcher : Karlberg JPE

Project Title:

Long-term health consequences of insults in early life

Investigator(s):

Karlberg JPE, Low LCK

Department:

Paediatrics & Adolescent Med

Source(s) of Funding:

Health Services Research Fund - Full Grants

Start Date:

11/1995

 

Abstract:

To understand the impact of early insults for health in adult-hood.

 

List of Research Outputs

 

Ansari M.T., Mahmood M.T. and Karlberg J.P.E., The association between seated immobility and local lower-limb venous coagulability in healthy adult volunteers: a simulation of prolonged travel immobility, Blood Coagulation and Fibrinolysis. 2006, 17 (5): 335-341.

 

Karlberg J.P.E., Clinical Trials in Paediatrics, Textbook of Clinical Trials, 2nd Edition. 2007, 701-710.

 

Karlberg J.P.E., Clinical Trials, Hong Kong vs. China, Drug Development in China, Strategies for Launching Discovery and Development Activities, 30-31 October 2006, San Francisco, California, USA. 2006.

 

Karlberg J.P.E., MGH-HKU-Nature China Forum - Molecular Medicine and Biopharma Opportunities, Hong Kong, 5-6 March 2007, 2007, 2007.

 

Karlberg J.P.E., On the Conduct of Registration Clinical Trials in Chinese Populations in China, Hong Kong and Taiwan, Drug Development in China, Strategies for Launching Discovery and Development Activities, 30-31 October 2006, San Francisco, California, USA. 2006.

 

Wang W.H., Huang J., Zheng G., Xia H.H.X., Wong R.W.M., Liu X.G., Karlberg J.P.E. and Wong B.C.Y., Effects of proton-pump inhibitors on function dyspepsia: A meta-analysis of randomized placebo-controlled trails, Clinical Gastroenterology & Hepatology. 2007, 5(2): 178-185.



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