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Biomedical subjects

D G Altman

Publications and source records attributed to D G Altman.

At least 235 records · Page 13Linked to original sources
PubMed1987

The cost-effectiveness of three smoking cessation programs.

This study analyzed the cost-effectiveness and distribution of costs by program stage of three smoking cessation programs: a smoking cessation class; an incentive-based quit smoking contest; and a self-help quit smoking kit. The self-help program had the lowest total cost, lowest per cent quit rate, lowest time requirement for participants, and was the most cost-effective. The most effective program, the smoking cessation class, required the most time from participants, had the highest total cost, and was the least cost-effective. The smoking contest was in-between the other two programs in total costs, per cent quit rate, and cost-effectiveness; it required the same time commitment from participants as the self-help program. These findings are interpreted within the context of community-based intervention in which the argument is made that cost-effectiveness is only one of several factors that should determine the selection of smoking cessation programs.

Adult↗
PubMed1986

Common DNA polymorphism within coding sequence of apolipoprotein B gene associated with altered lipid levels.

60 of 83 middle-aged white men had an XbaI restriction site polymorphism within the coding sequence of the apolipoprotein B gene. Subjects homozygous and heterozygous for the presence of an XbaI restriction site had mean serum triglyceride levels 36% higher (p = 0.02) than those in homozygotes without the restriction site; there was a less substantial difference (p = 0.03) in serum cholesterol. The findings supported a dominant pattern of inheritance. The presence of this restriction site may increase the risk of atherosclerotic disease.

Apolipoproteins B↗
PubMed1986

Confidence intervals rather than P values: estimation rather than hypothesis testing.

Overemphasis on hypothesis testing--and the use of P values to dichotomise significant or non-significant results--has detracted from more useful approaches to interpreting study results, such as estimation and confidence intervals. In medical studies investigators are usually interested in determining the size of difference of a measured outcome between groups, rather than a simple indication of whether or not it is statistically significant. Confidence intervals present a range of values, on the basis of the sample data, in which the population value for such a difference may lie. Some methods of calculating confidence intervals for means and differences between means are given, with similar information for proportions. The paper also gives suggestions for graphical display. Confidence intervals, if appropriate to the type of study, should be used for major findings in both the main text of a paper and its abstract.

Adult↗
PubMed1986

Statistical methods for assessing agreement between two methods of clinical measurement.

In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.

Diagnosis↗
PubMed1986

A framework for evaluating community-based heart disease prevention programs.

This paper reviews issues that arise in the evaluation of community-based heart disease prevention programs and offers suggestions for improving future evaluations of these programs. A framework encompassing the evaluation of process, impact and social relevance guides this discussion. The goal of the framework is to divide the question, "do community-based health programs work?", into more easily answered evaluation questions. In doing so, interventions that promote the health of community residents are likely to be designed and implemented successfully.

Community Health Services↗
PubMed1986

Use of a prognostic index in evaluation of liver transplantation for primary biliary cirrhosis.

In the Cambridge/King's College Hospital program, one of the main criteria for recommendation of a liver transplant for a patient with primary biliary cirrhosis (PBC), as in other types of end-stage liver disease, has been the overall assessment that survival was likely to be less than one year. In the present study, a recently developed prognostic model, based on six variables, was used retrospectively to estimate the likely survival without transplantation of the first 29 patients receiving a transplant for PBC. Median estimated survival time for the complete group of patients was five months and in only four patients was survival in the absence of transplantation estimated to be more than one year. Comparison of actual survival curves after transplantation with the estimated survival in the absence of such a procedure shows that, despite an initial higher mortality related to surgery and the immediate postoperative period, grafting was associated with a statistically significant improvement in overall survival. No correlation between the outcome after transplantation and the severity of preexisting liver disease, (as assessed by the expected survival) could be determined, but further assessment of preoperative variables is warranted.

Adult↗
PubMed1986

Racial differences in red cell indices.

A high prevalence of iron deficiency was found in apparently healthy Asian immigrant children in Harrow. After excluding children with overtly abnormal red cell indices, Asian and European children had identical haemoglobin values, but Asian children had much lower mean cell volume and mean corpuscular haemoglobin values and higher red blood cell values.

Asia↗
PubMed1985

Is the blood pressure the same in both arms?

It is generally believed that there are blood pressure differences between the right and left arms, but most of the validation studies have used nonsimultaneous measurements. It is important to know whether there is a difference, as methodological comparisons are often made using a different technique on each arm. We have measured the blood pressure simultaneously in both arms in 91 patients, using two observers and two cuffs to provide eight measurements in a fully balanced design. The mean difference in blood pressure between the arms (left/right) was -1.3 (SE 0.4)/1.1 (SE 0.3) mmHg. Mean differences of the same magnitude were found between the two observers, and between the cuffs. Thus, no systematic difference of any consequence was found, although individual patients had mean between-arm differences in blood pressure of up to 10 mmHg. These results suggest that no significant bias is introduced in methodological comparisons that use both arms.

Adult↗
PubMed1985

Utilization of a telephone cancer information program by symptomatic people.

People with undiagnosed symptoms of cancer who called the Cancer Information Service (CIS), a toll-free telephone information program, were surveyed about their experiences with the program and the effects it had on their post-call behavior. The findings indicate that 75 percent of respondents who had not contacted a health professional before their call to the CIS did so after their call and 40 percent shared the information they obtained with other people. People who contacted a health professional after their call, compared to those who did not, were more likely to have called the CIS specifically for a physician referral or because they did not know whom else to contact, to have friends with cancer, to have had their most important question answered by the CIS, to have health insurance, and to report the influence of other people on their health actions. Interestingly, only half the respondents reported that they definitely would have contacted a health professional had the CIS not been available. The CIS, therefore, might be a link between symptomatic people and appropriate health services. Even so, about one-third of the sample did not know what illness they had or were still awaiting the outcome of medical tests up to several months after their call. Although the CIS was not the only source of health information utilized by respondents, the data demonstrate the important role that telephone information serves in the secondary prevention of cancer and in the delivery of effective health programs.

Adolescent↗
PubMed1985

Beneficial effect of azathioprine and prediction of prognosis in primary biliary cirrhosis. Final results of an international trial.

The effect of azathioprine on survival of patients with primary biliary cirrhosis was studied prospectively in a multinational, double-blind, randomized clinical trial including 248 patients of whom 127 received azathioprine and 121 placebo. There were 57 deaths in the azathioprine group and 62 in the placebo group. The actual survival was slightly longer during azathioprine than during placebo treatment. Using Cox multiple regression analysis and adjusting for slight imbalance between the two treatment groups, the therapeutic effect of azathioprine was statistically significant (p = 0.01), with azathioprine reducing the risk of dying to 59% of that observed during placebo treatment (95% confidence interval 40%-90%) or improving survival time by 20 mo in the average patient. Furthermore, azathioprine slowed down progressing incapacitation. Side effects of azathioprine were relatively few. The analysis revealed that the following five variables independently implied poor prognosis: high serum bilirubin, old age, cirrhosis, low serum albumin, and central cholestasis. These factors were combined to a "prognostic index" for prediction of outcome in new patients. The index was validated on independent patient data. On the basis of these results we recommend azathioprine as a routine treatment of primary biliary cirrhosis.

Actuarial Analysis↗
PubMed1985

Indirect measurement of blood pressure during exercise testing can be misleading.

Indirect blood pressures recorded with a random zero sphygmomanometer were compared with simultaneous intra-arterial blood pressures recorded with the Oxford system. Twenty five patients undertook a graded bicycle exercise test, cycling at workloads increasing from 41, 65, 114, and 163 W (250 to 400, 700, and 1000 kpm per min) with each grade being maintained for three minutes unless the exercise test was terminated earlier at the point of fatigue. Intra-arterial pressures were recorded continuously and indirect measurements made at steady state levels in the 30 seconds before each change in grade and immediately after the termination of the exercise protocol. The mean difference in systolic blood pressure at 5.5 minutes of exercise showed that the indirect measurement underestimated the direct measurement. Immediately after the termination of exercise the blood pressure fell precipitiously to a highly significant degree. For both systolic and diastolic pressures there was considerably individual variability. These data confirm that indirect methods of blood pressure measurement during dynamic exercise testing are inaccurate and may provide misleading information.

Adult↗
PubMed1985

Quantitation in inflammatory bowel disease using computerised interactive image analysis.

Objective measurements of various histological features in rectal biopsy material were made using computerised interactive image analysis. Analysis of the resulting data by forward stepwise discriminant analysis showed that biopsies from patients with ulcerative colitis and infective diarrhoea could be distinguished from each other and from normal biopsies; they could not, however, be distinguished from biopsies of patients with Crohn's disease, which behaves as a heterogeneous entity rather than a single disease. The measurements showed that the crypt atrophy described in active ulcerative colitis may be a misnomer, the appearances being due to an increase in mucosal depth and alteration in crypt configuration rather than a true atrophy. Unexpectedly, the ratio of crypt cell height to surface cell height gave the best separation of Crohn's disease from ulcerative colitis.

Colitis, Ulcerative↗