Biomaterial Database

Reproducibility or variability of casual and ambulatory blood pressure data: implications for clinical trials. 1990

A J Coats

Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford, UK.

Lack of reproducibility in a blood pressure measurement leads to a systematic underestimate of risk when only a few highly variable blood pressure estimates are taken. This has been called the 'regression dilution bias'. To determine the real risk produced by a lifelong blood pressure elevation requires many readings in order to estimate 'usual' blood pressure. Multiple readings improve the precision of the estimate of usual blood pressure. The 1-month variability in clinic and in 1, 2, 3, 4, 8 and greater than 20 ambulatory diastolic blood pressure values, measured in 100 untreated hypertensives, showed that whether the variability is measured as the standard deviation of the difference or as intermonth autocorrelations, the precision is improved by increasing numbers of blood pressure readings. The risks calculated from an elevation in blood pressure would have been up to 69% greater had ambulatory diastolic blood pressure been used to classify subjects in epidemiological studies. Repeat epidemiological investigations of the risks posed by certain levels of ambulatory blood pressure are needed.

UI	MeSH Term	Description	Entries
D006973	Hypertension	Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.	Blood Pressure, High,Blood Pressures, High,High Blood Pressure,High Blood Pressures
D001795	Blood Pressure Determination	Techniques used for measuring BLOOD PRESSURE.	Blood Pressure Determinations,Determination, Blood Pressure
D002986	Clinical Trials as Topic	Works about pre-planned studies of the safety, efficacy, or optimum dosage schedule (if appropriate) of one or more diagnostic, therapeutic, or prophylactic drugs, devices, or techniques selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects. This concept includes clinical trials conducted both in the U.S. and in other countries.	Clinical Trial as Topic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012307	Risk Factors	An aspect of personal behavior or lifestyle, environmental exposure, inborn or inherited characteristic, which, based on epidemiological evidence, is known to be associated with a health-related condition considered important to prevent.	Health Correlates,Risk Factor Scores,Risk Scores,Social Risk Factors,Population at Risk,Populations at Risk,Correlates, Health,Factor, Risk,Factor, Social Risk,Factors, Social Risk,Risk Factor,Risk Factor Score,Risk Factor, Social,Risk Factors, Social,Risk Score,Score, Risk,Score, Risk Factor,Social Risk Factor
D015203	Reproducibility of Results	The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.	Reliability and Validity,Reliability of Result,Reproducibility Of Result,Reproducibility of Finding,Validity of Result,Validity of Results,Face Validity,Reliability (Epidemiology),Reliability of Results,Reproducibility of Findings,Test-Retest Reliability,Validity (Epidemiology),Finding Reproducibilities,Finding Reproducibility,Of Result, Reproducibility,Of Results, Reproducibility,Reliabilities, Test-Retest,Reliability, Test-Retest,Result Reliabilities,Result Reliability,Result Validities,Result Validity,Result, Reproducibility Of,Results, Reproducibility Of,Test Retest Reliability,Validity and Reliability,Validity, Face
D015924	Blood Pressure Monitors	Devices for continuously measuring and displaying the arterial blood pressure.	Monitors, Blood Pressure,Sphygmomanometers, Continuous,Blood Pressure Monitor,Continuous Sphygmomanometer,Continuous Sphygmomanometers,Monitor, Blood Pressure,Pressure Monitor, Blood,Pressure Monitors, Blood,Sphygmomanometer, Continuous
D015982	Bias	Any deviation of results or inferences from the truth, or processes leading to such deviation. Bias can result from several sources: one-sided or systematic variations in measurement from the true value (systematic error); flaws in study design; deviation of inferences, interpretations, or analyses based on flawed data or data collection; etc. There is no sense of prejudice or subjectivity implied in the assessment of bias under these conditions.	Aggregation Bias,Bias, Aggregation,Bias, Ecological,Bias, Statistical,Bias, Systematic,Ecological Bias,Outcome Measurement Errors,Statistical Bias,Systematic Bias,Bias, Epidemiologic,Biases,Biases, Ecological,Biases, Statistical,Ecological Biases,Ecological Fallacies,Ecological Fallacy,Epidemiologic Biases,Experimental Bias,Fallacies, Ecological,Fallacy, Ecological,Scientific Bias,Statistical Biases,Truncation Bias,Truncation Biases,Bias, Experimental,Bias, Scientific,Bias, Truncation,Biase, Epidemiologic,Biases, Epidemiologic,Biases, Truncation,Epidemiologic Biase,Error, Outcome Measurement,Errors, Outcome Measurement,Outcome Measurement Error