Introduction
2 Scientific background and explanation of rationale
Example
"The carpal tunnel syndrome is caused by compression of the median nerve at the wrist and is a common cause of pain in the arm, particularly in women. Injection with corticosteroids is one of the many recommended treatments.
One of the techniques for such injection entails injection just proximal to (not into) the carpal tunnel. The rationale for this injection site is that there is often a swelling at the volar side of the forearm, close to the carpal tunnel, which might contribute to compression of the median nerve. Moreover, the risk of damaging the median nerve by injection at this site is lower than by injection into the narrow carpal tunnel. The rationale for using lignocaine (lidocaine) together with corticosteroids is twofold: the injection is painless, and diminished sensation afterwards shows that the injection was properly carried out.
We investigated in a double blind randomised trial, firstly, whether symptoms disappeared after injection with corticosteroids proximal to the carpal tunnel and, secondly, how many patients remained free of symptoms at follow up after this treatment" (69).
Explanation
Typically, the introduction consists of free-flowing text, without a structured format, in which authors explain the scientific background or context and the scientific rationale for their trial. The rationale may be explanatory (for example, to compare the bioavailability of two formulations of a drug or assess the possible influence of a drug on renal function) or pragmatic (for example, to guide practice by comparing the clinical effects of two alternative treatments). Authors should report the evidence of the benefits of any active intervention included in a trial. They should also suggest a plausible explanation for how the intervention under investigation might work, especially if there is little or no previous experience with the intervention (70).
The Helsinki Declaration states that biomedical research involving people should be based on a thorough knowledge of the scientific literature (71). That is, it is unethical to expose human subjects unnecessarily to the risks of research. Some clinical trials have been shown to have been unnecessary because the question they addressed had been or could have been answered by a systematic review of the existing literature (72). Thus, the need for a new trial should be justified in the Introduction. Ideally, the introduction should include a reference to a systematic review of previous similar trials, or a note of the absence of such trials (73).
In the first part of the Introduction, authors should describe the problem that necessitated the work. The nature, scope, and severity of the problem should provide the background and a compelling rationale for the study. This information is often missing from reports. Authors should then describe briefly the broad approach taken to studying the problem. It may also be appropriate to include here the objectives of the trial (item 5).
Page last edited: 17 July 2007
