The Principle of Intention to Treat in Clinical Trial, Essay Example

1. Discuss the principle of intention to treat in clinical trial. Be sure to address why study results might be misleading if you include only those cases with evaluable data or cases that completed the study.

The Intention to treat (ITT) is one of the more difficult methodological ideas to understand why we should compare outcomes among grouping of people on the basis of what they were randomized to get instead of what they did get.

Determining the sample of patients to be analyzed is a key step in reporting clinical trials. Ideally, a research paper should account for all its subjects who were eligible and started the trial, explaining the reasons behind some not finishing the trial. In an ITT analysis, all the study participants are included in the analyses as part of the groups to which they were allocated, no matter whether they have completed the study or not. It keeps them in the original groups for the purpose of statistical analysis.

If these patients are not accounted for in the analysis of the results, the results and conclusion might be misleading and important effects of the intervention in terms of, for example, intolerable side-effects, can be missing or lost. Exclusion from the final analysis leads to a bias in interpretation of the results. This is referred to as attrition bias (also known as exclusion bias).

2. Discuss the statement “the key consideration in assessing a sample in a uantitative study is its represenativeness” Most research samples in nursing and other disciplines are ” convience samples ” or anothertype of non profitability sample. Explain how convience samples might affect the validity of findings.

“The key consideration in assessing a sample in a quantitative study is its representativeness” – the extent to which the sample is similar to the population and avoids bias. Convenience sampling has probably been the most frequently used sampling method in nursing research. It is also referred to as accidental or incidental involves choosing voluntarily available people or objects for a study. Convenience samples have obvious advantages over probability samples, primarily with respect to logistics and cost. However, selection using convenience methods can introduce bias into the sample.

Even greater potential for selection bias exists if the researcher is involved personally in selecting the subjects. Consciously or unconsciously, the researcher’s predetermined ideas about the research might affect subject inclusion.

A specific kind of convenience sample that violates both randomness and independence is snowball sampling. In snowball sampling, each subject is asked to recruit other subjects. Although this may be the only way to reach some groups that possess sensitive characteristics (for example, alcoholics, drug addicts, or pregnant teens), the subjects are not independent and randomly selected, and so generalizing the results may be limited.

3. Discuss the use of surrogate outcomes in clinical research and the pro and cons of using surrogate measures when evaluating an intervention.

Surrogate outcomes are very sensitive to the treatment’s direct effect and therefore are more responsive variables than patient-centered outcomes. Since surrogate outcomes are frequently laboratory or physiologic measures they can usually be measured reliably and precisely. By increasing the sensitivity, precision, and reliability of the outcome variable, surrogate outcomes can increase the statistical power of clinical studies requiring smaller numbers of patients to demonstrate a statistically significant effect.

Surrogate outcomes hold out the promise of shorter studies of fewer patients to demonstrate the effectiveness of treatments. This is particularly a desirable in chronic diseases where a treatment’s effect on survival or quality of life may not be observed for years while its effect on a surrogate may be observed over weeks or months.

4. Define construct validity and explain why it is important to consider this when selecting an existing instrument or developing a new instrument to be used in a study.

Construct validity means that the instrument measures what it purports to and not something else. Validating an instrument is a challenging task. Construct validity is concerned with what construct is the existing or new instrument actually measuring? The more abstract the concept, the more difficult it is to establish the construct validity of the measure; at the same time, the more abstract the concept, the less suitable it is to use a criterion-related validation approach.

One means of establishing construct validity is by correlating performance on the test with performance on a test for which construct validity has already been determined. For example, performance on a newly developed intelligence test might be correlated with performance on an existing intelligence test for which construct validity has been previously established.

5. Discuss why pragmatic clinical trials that use hybrid designs are likely to play an increasingly important role in nursing intervention research.

Pragmatic clinical trials that use hybrid designs are likely to play an increasingly important role in nursing intervention research. This model of intervention research is, at this point, more of an ideal than an actuality. Pragmatic clinical trials are studies designed to provide information to clinical decision makers, and involve hybrid designs aimed at reducing the gap between efficacy and effectiveness studies (i.e., between internal and external validity).

Pragmatic clinical trials address practical questions about the benefits and risks – as well as its costs – as they would unfold in routine clinical practice. Hybrid designs link efficacy and effectiveness in nursing intervention research. A key feature of this process is the development of an intervention theory from which the hybrid design of an intervention flow. Intervention research proceeds in several phases, and an especially important phase is early development work that frequently involves mixed research method.