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Figure 12.4.1 Adjustment for covariate in estimation of treatment effect. Case I Common slope. Figure 12.4.2 Adjustment for covariate in estimation of treatment effect. Case II Different slopes, same direction but different magnitude. Figure 12.4.2 Adjustment for covariate in estimation of treatment effect. Case II Different slopes, same direction but different magnitude. estimate the common treatment effect over the entire range of the covariate. Figure 12.4.2 depicts a situation where the...

Descriptive And Inferential Statistics

Dietrich and Kearns (1986) divided statistics into two broad areas, namely descriptive and inferential statistics. Descriptive statistics is the science of summarizing or describing data, while inferential statistics is the science of interpreting data in order to make estimates, hypotheses testing, predictions, or decisions from the samples to the targeted population. In clinical trials, data are usually collected through case report forms which are designed to capture clinical information...

Bias And Variability

As was indicated earlier, the FDA requires that the results from clinical trials be accurate and reliable in order to provide a valid and unbiased assessment of true efficacy and safety of the study medication. The accuracy and reliability are usually referred to as the closeness and the degree of the closeness of the clinical results to the true value regarding the targeted patient population. The accuracy and reliability can be assessed by the bias and variability of the primary clinical...

Continual Reassessment Method Phase I Designs

As mentioned above, patients in cancer phase I trials are often those with terminal cancer and at high risk of death. The characteristics of the anti-cancer cytotoxic agents evaluated in phase I cancer trials are that (1) they produce fatal toxicity at a higher dose level, (2) they yield little or no effectiveness at lower dose levels, and (3) except for some scarce animal data, no information about the dosing range is available. The standard dose escalation design and one-stage or two-stage...

Multicenter Trial

When conducting a clinical trial, it may be desirable to have the study done at a single study site if (1) the study site can provide an adequate number of relatively homogeneous patients that represent the targeted patient population under study and (2) the study site has sufficient capacity, resources, and supporting staff to sponsor the study. One of the advantages for a single-site study is that it provides consistent assessment for efficacy and safety in a similar medical environment. As a...

Risk of Exposure

In clinical trials the toxicity or risk of exposure to a drug can generally described as a function of the exposure to the drug where the exposure to the drug depends on the dose and time of exposure. If we assume a constant dose, then the toxicity is a function of the time of exposure. The toxicity or risk of exposure is usually measured by some parameters such as occurrence, number, duration, and time pattern of an event. The event may be an absorbing (irreversible) event (e.g., death), a...

Vaccine Clinical Trials

Similar to clinical development of drug products, there are four phases of clinical trials in vaccine development. Phase I trials are referred to early studies with human subjects. The purpose of phase I trials is to explore the safety and immunogenicity of multiple dose levels of the vaccine under investigation. Phase I trials are usually of a small scale. Phase II trials are to assess the safety, immunogenicity, early efficacy of selected doses of the vaccine, and generate hypotheses for...

Parallel Group Designs

A parallel group design is a complete randomized design in which each patient receives one and only one treatment in a random fashion. Basically there are two types of parallel group design for comparative clinical trials, namely, group comparison or parallel-group designs and matched pairs parallel designs. The simplest group comparison parallel group design is the two-group parallel design which compares two treatments e.g., a treatment group vs. a control group . Each treatment group...