| study, crossover | A type of clinical trial in which the study subjects receive each treatment in a random order. In this type of study, every patient serves as his or her own control. (12 Dec 1998) |
|---|---|
| study, cross-sectional | A study done at one time, not over the course of time. A cross-sectional study a disease such as aids might be designed to learn its prevalence and distribution within the population at one point in time. Also known as a synchronic study. (12 Dec 1998) |
| study, diachronic | See: Study, longitudinal. (12 Dec 1998) |
| study, longitudinal | A study done over the passage of time. For example, a longitudinal study of children with down syndrome (trisomy 21) might involve the study of 100 children with this condition from birth to 10 years of age. Also called a diachronic study. The opposite of a cross-sectional (synchronic) study. (12 Dec 1998) |
| study, preclinical | A study to test a drug, procedure or medical treatment in animals. The aim is to collect data in support of safety. Preclinical studies are required before clinical trials can be started. (12 Dec 1998) |
| study, synchronic | See: Study, cross-sectional. (12 Dec 1998) |
| synchronic study | <epidemiology> A study in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with longitudinal studies which are followed over a period of time. Synonym: horizontal study. (18 Jul 2002) |
| diachronic study | A study done over the course of time. For example, a longitudinal study of children with Down syndrome (trisomy 21) might involve the study of 100 children with this condition from birth to 10 years of age. Also called a longitudinal study. The opposite of a synchronic (cross-sectional) study. (12 Dec 1998) |
| double-blind study | A study in which neither the experimenter nor any other assessor of the results, including patients, know which group is subject to which procedure, thus helping assure that the biases or expectations of either will not influence the results. (05 Mar 2000) |
| epidemiologic study characteristics | Types and formulations of studies used in epidemiological and clinical research. (12 Dec 1998) |
| twin study | A method of detecting genetic causes in human traits and genetic factors in behaviour using sets of twins. (12 Dec 1998) |
| foetal doppler study | <radiology> Non-stress test (NST), external monitoring for 20 minutes; poor specificity, greater than4 foetal heart accelerations (greater than15 bpm over baseline for 15 seconds) following foetal movement in foetus greater than34 weeks, no heart accelerations in immaturity, sleep, maternal sedation contraction stress test (CST), external monitoring after oxytocin or maternal breast stimulation, greater than 3 uterine contraction in 10 minutes; 50% specificity uterine and umbilical artery waveform, elevated systolic:diastolic ratio = increased vascular resistance foetal aortic flow volume, 185-246 ml/kg/min see also: biophysical profile, intrauterine growth retardation (IUGR) (12 Dec 1998) |
| follow-up study | Study in which persons exposed to risk or given a designated preventive or therapeutic regimen are observed over a period or at intervals to determine the outcome of the exposure or regimen. (05 Mar 2000) |
| Framingham Heart study | <epidemiology> Ongoing epidemiologic study of a cohort of over 5,000 of the population of Framingham, MA conducted since 1949 under the auspices of the National Institutes of Health and Boston University. (05 Mar 2000) |
| longitudinal study | <epidemiology> A study taking place over time. If individuals are followed, this is a longitudinal cohort study. If individuals are not followed, but classes (usually age classes) are restudied, this is a longitudinal cross-sectional study. The converse of a horizontal study. (05 Dec 1998) |