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Biomedical subjects

D G Altman

Publications and source records attributed to D G Altman.

299 records · Page 17Linked to original sources
PubMedDate not supplied

Statistics in medical journals.

The general standard of statistics in medical journals is poor. This paper considers the reasons for this with illustrations of the types of error that are common. The consequences of incorrect statistics in published papers are discussed; these involve scientific and ethical issues. Suggestions are made about ways in which the standard of statistics may be improved. Particular emphasis is given to the necessity for medical journals to have proper statistical refereeing of submitted papers.

Ethics↗
PubMedDate not supplied

Does placebo lower blood-pressure?

The effect of placebo on blood-pressure levels in 20 hypertensive patients was examined as part of a double-blind randomised controlled trial with indoramin. Blood-pressure was measured by both standard sphygmomanometry and ambulant intra-arterial monitoring. Blood-pressure reduction during the placebo phase, as measured by sphygmomanometry in the outpatient clinic, was highly significant for both systolic and diastolic pressures. In the same subjects, concomitant assessment by ambulatory monitoring showed no significant effect of placebo on intra-arterial pressure. After indoramin treatment blood-pressures measured in the clinic showed a mean reduction of 6/8 mm Hg whereas intra-arterial monitoring showed mean reductions of 18/13 mm Hg. The placebo response, therefore, appears to be an artifact of clinic blood-pressure measurement and its use as a control value in pharmacological trials may lead to serious underestimation of the efficacy of the active drug.

Adult↗
PubMedDate not supplied

Assessing birth weight-for-dates on a continuous scale.

Mathematical models have been fitted to the widely used standards of birth weight by gestational age that were published by Thomson, Billewicz and Hytten (1968). The models give a close fit to the data and allow an individual infant's weight to be scored on a continuous scale as a number of standard deviations from the expected weight.

Birth Order↗
PubMedDate not supplied

Alpha-adrenoreceptor blockade with indoramin in hypertension.

We have evaluated the effects of indoramin, an alpha-adrenoreceptor blocking drug, used as sole therapy in a group of 27 patients with essential hypertension. Blood pressure and heart rate were measured continuously over prolonged ambulatory periods using an established invasive technique before and after six weeks of therapy. The protocol was randomised, double-blind, and with double-dummy placebo control. A standardised programme of physiological stress testing was also performed during each study. Placebo produced no appreciable change in the levels or patterns of blood pressure over 24-h periods, but indoramin produced a significant reduction, which was particularly marked during the night. Physiological testing did not reveal any postural hypotension, and the response to dynamic and isometric exercise was modified in level but not in degree of change. There were many unwanted effects, which may limit the clinical value of this drug.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

Strategies for community health intervention: promises, paradoxes, pitfalls.

This paper provides a rationale for intervening on shared determinants of health at the community level of analysis, presents strategies for intervening on shared determinant risks at the community-level of analysis, and illustrates through a case study of a youth program how a small-scale community intervention on shared determinants might work in practice. Although there is a long history of community intervention to improve health, high quality research on these interventions has been conducted only recently. In evaluating the usefulness of a community intervention, the distinction between relative risk and population-attributable risk is not always made clear. These two distinct types of risk are reviewed considering their implications for what risk factors are targeted by community interventions and what criteria are reasonable to apply in evaluating the utility of these interventions. A role for linking root cause analysis with attributable risk and interventions to reduce risk is presented.

Adolescent↗
PubMedDate not supplied

A trial of the comparability of peak expiratory flow meters in schoolchildren.

In many circumstances it may not be possible to measure peak expiratory flow rate on all subjects using the same meter. A small trial was carried out to assess the variability of such meters. Five newly calibrated adult Wright peak expiratory flow meters, which gave comparable readings when rechecked on another rotameter, were compared in a trial on 160 schoolchildren. Each child blew once into each meter, and the design was balanced so that the effect of order of blow was eliminated. Statistically significant differences were found between the meters, although the difference between any pair of meters was less than 5% of the average peak flow rats. Since the meters were chosen because they were very similar it is likely that larger differences would be found in other circumstances. This could be an important source of error in multicentre studies where several meters have to be used.

Child↗
PubMedDate not supplied

Evaluation of the Remler M2000 blood pressure recorder. Comparison with intraarterial blood pressure recordings both at hospital and at home.

The Remler M2000 is a semiautomated device that has been used to collect epidemiological data and assess blood pressure variability. It has been subjected to limited evaluation in operation, however, and no studies of its accuracy away from the hospital or office environment have been undertaken. We recruited a group of 28 patients with essential hypertension who were undergoing intraarterial ambulatory blood pressure monitoring and compared the intraarterial recordings with those made with the Remler instrument both at home and in the hospital. The Remler recordings were also compared with simultaneous indirect blood pressure measurements made with the random zero sphygmomanometer. The mean difference between the Remler and intraarterial blood pressure recordings was -3/7 in the hospital and 7/0 at home. All standard deviations were greater than 10 mm Hg, indicating large between-subject variability. Overall, the relationship of the Remler M2000 readings to intraarterial pressures was as close if not closer than standard indirect sphygmomanometry and thus might provide useful data for epidemiological surveys or drug trials. It would appear that for accurate measurement of short-term blood pressure variation and 24-hour recording, intraarterial recording is the method of choice.

Adult↗