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Lesson 10 How to start a research. Types of studies. Areas of medical researches in medicine

Vocabulary and reading

be similar - идентичный

compare - сравнивать

expose - оказывать воздействие, сравнивать

contribute to - способствовать

relationship - связь

intervention - влияние

proof - доказательство

equal - равный

step - шаг

hospital records - история болезни

reliable - надежный

trial - испытание

I. Read and translate the text

In a case-control study, a group of people suffering from a disease (the cases) is compared with a group who do not have the disease, but are similar in other ways (the controls). The two groups, the participants in the study, are compared to see if they were exposed to a possible risk factor or not. A risk factor is something which may contribute to the cause of disease. This type of study is often used as a first step in identifying the cause of a disease.

Cohort studies

In a cohort study, a group (cohort) of people (subjects) who are similar is studied over a period of years (a longitudinal study) to determine if there is a relationship between exposure to a risk factor and development of a disease. At the beginning of a prospective study, none of the subjects has the disease. They are followed up for a number of years, and at the end of the period, those who have developed the disease are compared with those who have not. In a retrospective study, the researchers look back, by studying hospital records for example, at what has happened in the past, comparing subjects who have developed the disease with those who have not. In a cohort study and in a case-control study the subjects are only observed and there is no intervention such as drug treatment or surgery. A cohort study is a more reliable method of identifying the cause of disease than a case-control study. But for proof of cause, a trial is needed.

Trials

In a trial, a group of people who are suffering from a disease are given a particular treatment. To determine the effectiveness of the treatment, a controlled trial is performed. Two groups are studied: one group (the study group) is given the treatment and the other (the control group) is not. The controls may be given a placebo – something which seems to be identical to the treatment but which has no effect. If there is an equal possibility that patients may be selected for the study group or for the controls, the trial is said to be randomized. A randomized controlled trial makes bias – error in a study which influences the results – less likely. An additional way of removing bias is blinding: patients do not know if they are receiving the treatment or the placebo. If, in addition, the researchers do not know who is receiving the treatment, the trial is a double blind trial. Randomized controlled trials are used to test treatments or preventive measures.

Variables

If the subjects in a study are all aged 50, then age is a constant in the study. If their ages range from 20 to 70, then age is a variable. A confounding variable is any variable which is associated with both the disease and the risk factor being studied (for example, smoking in the case of cooks and lung cancer discussed in Unit 44). If such variables exist there is no way for the researcher to know whether the difference in the risk factor or the confounding variable is the one that is truly causing the disease.