![]() Many such questionnaires and patient self-rating scales (MMSE or QOLIE, for instance) were developed in another part of the world. These instruments and investigations have usually been well validated in the past, although the populations in which such validations were conducted may be different. Validity (Precision) and Reliability (Consistency)Ĭlinical research generally requires making use of an existing test or instrument. If we compare the exclusion criteria for the two meningitis studies mentioned above, we see that in the study by de Gans, patients with shunts, prior neurosurgery and active tuberculosis were specifically excluded in the Scarbrough study, however, such considerations did not apply as the locale was considerably different (sub-saharan Africa vs. After choosing an appropriate setting, attention must be turned to the inclusion and exclusion criteria. Hence, it is important to decide how you select your sample. If the sample was restricted to a particular age group, sex, socioeconomic background or stage of the disease, the results would be applicable to that particular group only. Here, the authors intentionally chose an outpatient setting (the patients were referred to the study clinic from a network of other physician clinics as well as local advertisements) so that their population would not include patients with more severe pathology (requiring hospital admission). investigating therapies in the treatment of migraine. ![]() On the other hand, consider the study by Holroyd et al. By the same logic, it would be inappropriate to study less-acute conditions in such a fashion as it would bias the study toward sicker patients. Because the studies involved acute conditions, they utilize the fact that sicker patients will seek hospital care to concentrate their ability to find patients with meningitis. Both studies are good examples of using the hospital setting. ![]() ![]() looked at the effect of adjunctive Dexamethasone in bacterial meningitis. The observations in a study may or may not be generalizable, depending on how closely the sample represents the population at large.Ĭonsider the following studies. On the other hand, acute diseases such as meningitis would have a similar profile in the hospital and in the community. Some diseases, such as migraine, may have a different profile when evaluated in the population than when evaluated in the hospital. One of the first steps in clinical study is choosing an appropriate setting to conduct the study (i.e., hospital, population-based). Our aim is to familiarize the reader with different sampling methods that can be appropriately used in medical research with different scenarios and challenges. We do not intend to provide a tailor-made design. The major objective of this article is to explain these initial steps. How good are serologic markers compared with CT scans in terms of identifying NCC? Which test (CT or blood test) is easier, safer and acceptable for this study? Do we have the expertise to carry out these laboratory tests and make interpretations? Which procedure is going to be more expensive? It is very important that the researcher spend adequate time considering all these aspects of his study and engage in discussion with biostatisticians before actually starting the study. In the example of NCC, should we use serological markers or CT scan findings as evidence of NCC? Such a question raises further questions. Further considerations in clinical research, such as the clinical setting, study design, selection criteria, data collection and analysis, are influenced by the disease characteristics, prevalence, time availability, expertise, research grants and several other factors. Once we have a fairly well-defined research question, we need to consider the best strategy to address these questions. In this paper, we focus attention on residents and younger faculty who are planning short-term research projects that could be completed in 2–3 years. For example, do persons with epilepsy have a higher probability of having serological (or computed tomography scan) markers for NCC? What proportion of persons with multiple lesions in the brain has Multiple Sclerosis (MS) Do children with pyogenic meningitis have a lesser risk of mortality if dexamethasone is used concomitantly with antibiotics?ĭesigning a clinical study involves narrowing a topic of interest into a single focused research question, with particular attention paid to the methods used to answer the research question from a cost, viability and overall effectiveness standpoint. Is there an association between neurocysticercosis (NCC) and epilepsy? Are magnetic resonance imaging changes good predictors of multiple sclerosis? Is there a benefit in using steroids in pyogenic meningitis? Typically, these questions lead us to set up more refined research questions. Clinical research often starts from questions raised at the bedside in hospital wards.
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