Biometrics - Services
Research Project Design and Development: Biostatisticians are available to Center members to discuss relevant statistical considerations of all aspects of study design. The shared resource assists investigators in defining study objectives, realistic endpoints, study population, randomization schema (when appropriate), quality assurance, sample size, and power analysis required to effectively answer research questions. The biostatistician then develops the statistical methods for data analyses. For laboratory experiments, biostatisticians help the investigator review experiments, the hypothesis to be tested or generated, the methodology to be used, and the characteristics of the data to be collected. Different methodologies for analyses may depend on whether the data collected will be discrete or continuous, clustered in time or space, and univariate or multivariate, or whether there are other variables. Recommendations are made regarding organization of data into appropriate databases. This approach is undertaken predominately for experiments involving cell lines or research animals and has resulted in several publications in collaboration with laboratory researchers .
Clinical investigators are required to utilize the Biometrics Shared Resource for all investigator-initiated clinical trials. During concept development, a biostatistician and the clinical investigator discuss the study objectives and endpoints. Depending on the type of study, the following information is reviewed:
For phase I studies, where the primary objective is to determine the maximum-tolerated dose, the dose-sequence levels, assumptions of the dose-toxicity relationships, dose escalation and/or de-escalation strategies, and statistical properties of sequential dose-adjustment methods are assessed
- For phase II studies, the magnitude of treatment effect that the protocol seeks to exclude and with which to power the study, and the associated type-I and type-II error rates are calculated
- The conclusions to be drawn from assays performed on tissues, serum, or other samples with the observed response are assessed
- For correlative clinical and laboratory studies, appropriate regression or association analyses are planned
- For all studies, patient characteristics that could affect response, survival, or other biological effects are calculated
- The sources of patients that are available for the study, including a realistic appraisal of sample heterogeneity and projected accrual rates and length of the study are evaluated
- Whenever applicable, appropriate models of pharmacokinetic and pharmacodynamic data are calculated
After reviewing the study with the principal investigator, the biostatistician writes the “Statistical Considerations Section” of the research protocol. This section includes the sample-size justification and other statistical design aspects, such as randomization, masking and stratification (when appropriate) as well as the statistical methods to be used for data analyses.
Biostatisticians are also available to discuss study objectives, endpoints, correlative markers and/or surrogate endpoints used for human chemoprevention clinical studies. The following information defined includes (1) an effect size that the protocol seeks to detect, (2) the magnitude of the effect size expected in the study, (3) the control group needed for comparison of the effect, (4) the correlations with the observed response to be drawn from assays performed on tissues, serum, or other samples; appropriate regression or association analyses for correlative clinical and laboratory studies, (5) the randomization procedures and tables, (6) subject or patient characteristics that could affect time-to-disease progression or survival (if sought), or other biological effects, (7) the sources of subjects that are available for the study, including a realistic appraisal of sample heterogeneity, and (8) the duration of the study. Following this evaluation, the biostatistician estimates the sample size and projected duration needed to complete the study and derives the power calculations. This information is discussed with the investigator and a design strategy and sample-size target is then finalized.
Development of Methodology: A quality service requires quality methods. In some instances, consultation on project design identifies the need to develop unique analytical methods to fully capitalize on the data, to conserve resources, to monitor the study, or to optimize experiments. Biometrics has developed statistical methods for a wide range of needs: analyzing DNA microarray data, small pilot studies for discovering biomarkers, algorithm-based designs for phase I cancer studies, model-based designs for phase I cancer studies, and adaptive designs for phase II cancer studies. The adaptive design has been used in three center-initiated phase II studies, including one planned for the Children’s Oncology Group.
Protocol and Grant Proposal Review: Members from Biometrics review grant proposals from basic, clinical, and public health science researchers. This includes grant applications for human and non-human studies, follow-up studies, and cross-sectional surveys.
Ongoing Study Monitoring: The biostatistician assigned to a specific trial periodically meets with the study investigator to provide ongoing assistance in the conduct of the trial. Interim analysis is provided as specified in the protocol. For laboratory investigators these ongoing meetings are at the request of the investigator. For clinical trials, a more defined process of ongoing monitoring has been established. The weekly Office of Human Research Services (OHRS) meetings provide Biometrics a means to learn about the status of each approved protocol, in terms of patient recruitment, adverse events, and possible protocol violations.
Computation and Statistical Analyses: Methods for appropriate data analyses depend on the objectives and design of the study. An outline of the data analysis plan (DAP) should be defined in the study proposal. To ensure consistently and efficiency, Biometrics established a standard operating procedure for developing the DAP. In general, to conduct and interpret the results of the statistical analysis used to test the hypotheses of a study, Biometrics: (1) provides a preliminary review of the data to ensure that the quality and assumptions required for the analysis are satisfied, (2) completes all statistical analyses required to test the hypotheses considered in the study (including interim analyses when required), and (3) creates tables and/or graphs describing the demographic characteristics of the subjects in the study, the characteristics of the data, and the range of values associated with measurements that could affect the response of interest. The biostatistician involved with producing the preliminary analyses, the statistical analysis, and the tables and graphs uses SAS and/or S-plus software on a Dell PC, or the Biometrics UNIX workstation system.
Data Reports/Publications: The Biometrics Shared Resource offers assistance in the production of data reports. To enhance quality, efficiency and consistency, standard operating procedures were developed for data spread sheet formats and statistical reports. In collaboration with center investigators, members of this shared resource meet the specific requirements for each study or protocol and for the submission of data for presentations, audits, and publication.
Education, Consultation, and Training Activities: Biometrics faculty support the education and training activities of the Cancer Institute. Biometrics helped develop the curriculum for the training program in clinical protocol development. Biometrics also plays an important role in the ongoing educational activities for training and mentoring grants. Additional shared resource activities include the teaching of credit-earning courses, seminar series, guest lectures, and individual educational/consulting assistance in study design and data interpretation.