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Biomedical subjects

D G Altman

Publications and source records attributed to D G Altman.

At least 217 records · Page 12Linked to original sources
PubMed1989

A method for combining matched and unmatched binary data. Application to randomized, controlled trials of photocoagulation in the treatment of diabetic retinopathy.

A method for combining matched and unmatched data is described and was applied to the results of randomized, controlled trials of photocoagulation in the treatment of diabetic retinopathy. A pooled estimate from the matched and unmatched studies was obtained by adaptation of the Mantel-Haenszel method, where the strata were unmatched studies and matched pairs within studies. A test of significance was based on the Mantel-Haenszel chi-square statistic, the latter also being used to calculate test-based confidence intervals. A test of homogeneity was performed by combining Mantel-Haenszel chi-square statistics from the matched and unmatched studies. By these methods, the combined estimate of the risk of deterioration of visual acuity for those receiving photocoagulation (relative to a risk of unity for those not receiving photocoagulation) was 0.37 (95 per cent confidence interval 0.29-0.46). The chi-square statistic (1 df) for an effect of treatment was 87.75 (p less than 0.0001). The chi-square statistic for homogeneity of relative risk among studies was 11.20 (4 df, p less than 0.05). However, this result was influenced disproportionately by one small matched study.

Diabetic Retinopathy↗
PubMed1989

Prognosis after liver transplantation for primary biliary cirrhosis.

Timing of transplantation for patients with primary biliary cirrhosis (PBC) requires identification not only of individual risk factors for the operation but estimation of survival with and without transplantation. To identify those risk factors and develop a prognostic model, 82 patients grafted for PBC since 1980 in the Birmingham and Cambridge/King's College Hospital series have been analyzed. Using logrank tests it was found that treatment with diuretics, hemoglobin above 10 g/dl, prothrombin time less than 5 sec prolonged, serum sodium above 130 mmol/L and serum bilirubin less than 350 mumol/L were all individually associated with a better prognosis. Using Cox regression analysis to identify independent variables, it was found that year of transplant, serum bilirubin, serum urea, and diuretic responsive ascites had a significant association with survival. Using these four variables, it was possible to develop a model to identify those patients with a good and a poor probability of survival after transplantation.

Bilirubin↗
PubMed1989

Duty calls: hospitals' responsibility for controlling the tobacco epidemic.

Growing public awareness of the health hazards associated with smoking and the growing social unacceptability of the smoking habit constitute one of the major public health revolutions of our time. In recent years, almost all of the country's major medical and health professional organizations have become actively involved in the tobacco control movement. Unfortunately, hospitals and their professional associations have been conspicuously absent from the ranks of those leading this effort. The authors argue that the American Hospital Association and individual hospitals have an opportunity and a duty to become leaders in the effort to reduce tobacco addiction in this country and around the world. Specific suggestions are provided for individual hospitals and for their professional associations to work toward protecting the health of nonsmokers by eliminating cigarette smoking in hospitals, to work for political solutions to eliminate efforts by tobacco companies to promote smoking, and to reduce the incidence of smoking initiation among young people.

Advertising↗
PubMed1988

Effects of chronic congestive heart failure secondary to coronary artery disease on the circadian rhythm of blood pressure and heart rate.

In 20 subjects with chronic congestive heart failure due to coronary artery disease, the 24-hour variability of ambulatory intraarterial blood pressure (BP) was studied using an improved Oxford Medilog system, and correlated with left ventricular function at rest. The mean radionuclide ejection fraction was 27% (range 10 to 42), the mean pulmonary arterial wedge pressure was 18 mm Hg (5 to 37) and the mean cardiac index was 2.8 liters/min/m2 (2 to 3.8). The 24-hour systolic BP and heart rate (HR) variability indexes were less than those of 22 normal volunteers (p less than 0.05) and were strongly correlated (p less than 0.05) with ejection fraction at rest and pulmonary arterial wedge pressure. Stepwise regression showed that a combination of the mean nocturnal HR and the standard deviation of the hourly mean systolic BP values accounted for 67% of the variability in ejection fraction between patients. Similarly, 73% of the variation in pulmonary wedge pressure was explained by combining the 24-hour mean HR and the mean nocturnal HR.

Aged↗
PubMed1988

The hidden effect of time.

It is customary to regard datasets as homogeneous with respect to the order of collection of the measurements. Examples are given in which this assumption is breached. Hidden time trends have implications for the design of studies, their analysis and interpretation. It is suggested that, if the order of observations is known, a plot by time should be performed, perhaps using a cusum.

Aged↗
PubMed1988

An immunohistochemical evaluation of c-erbB-2 expression in human breast carcinoma.

The c-erbB-2 gene codes for a putative transmembrane protein, similar in structure to the epidermal growth factor (EGF) receptor. Amplification of the gene has been described in a variety of human adenocarcinomas and is particularly well documented in breast carcinoma. It has been suggested that amplification is indicative of poor prognosis and, as such, is comparable with lymph node status as a predictor of clinical outcome. This study examines the suggestion indirectly by an immunohistochemical technique. Archival tissue from 195 patients with primary breast carcinoma was stained with the polyclonal antibody 21N, raised to amino acids 1243-1255, the C-terminus of the predicted amino acid sequence of the c-erbB-2 protein. Up to 10 year verified follow-up data were available on all patients. Staining compatible with significant amplification was observed in 17 patients. Using the chi-squared test for trend a significant correlation was found between staining and grade (P = 0.04) but not with either node or receptor status. No significant association was found between staining and clinical outcome although there was a tendency for patients with stained tumours to have a worse prognosis. A Cox regression analysis was used to adjust for node status and grade and still no correlation was revealed between staining and prognosis. However a study of this size in which only a small number of patients have been found to have stained tumours does have wide confidence limits. Comparable staining observed in in situ and infiltrating components of tumours suggests that amplification is an early event in carcinogenesis. Similar staining in primary and subsequent metastatic lesions was also noted. It is considered that further studies at both the DNA/mRNA and protein levels are required to confirm the significance of c-erbB-2 amplification in human breast carcinoma.

Adult↗
PubMed1988

Antagonism of morphine-induced respiratory depression with nalmefene.

The duration of respiratory depression induced by morphine 10 mg/70 kg was studied following the administration of one of two opioid antagonists. Respiratory measurements included: (i) the ventilatory response to carbon dioxide, described in two ways--the minute ventilation at an end-tidal carbon dioxide partial pressure of 8 kPa (VE8) and the log slope of the ventilatory response to carbon dioxide; (ii) resting end-tidal carbon dioxide partial pressure; (iii) rate of ventilation. One hour after administration of morphine, one of the following was given i.v.: nalmefene 0.4 mg/70 kg; naloxone 0.4 mg/70 kg (low dose); naloxone 1.6 mg/70 kg (high dose); or saline placebo. The depression of VE8 by morphine was antagonized by all three treatments for the 1.5 h after the injection. However, for the 1.5-6 h after antagonist, VE8 following naloxone became depressed, whereas VE8 after nalmefene remained significantly increased compared with other treatments. Nalmefene restored the slope of the ventilatory response to baseline for 6 h and differed significantly from low but not high dose naloxone. Resting end-tidal carbon dioxide measurements demonstrated that nalmefene activity exceeded that of low but not high dose naloxone over the 1.5-4.5 h period. Rate of ventilation was not different between treatments.

Adult↗
PubMed1988

Cigarette advertisements in magazines: evidence for a differential focus on women's and youth magazines.

Cigarette advertisements in eight popular magazines from 1960 to 1985 were examined. The magazines were selected to represent different market segments, particularly women and youth. Across all eight magazines, the average number of cigarette ads per issue increased substantially following the 1971 television ban on cigarette ads. Moreover, beginning in the late 1960s and early 1970s, proportionately more ads were placed in women's and youth-oriented magazines than in magazines which targeted other population segments. These data suggest that the tobacco industry may have responded to decreases in the number of smokers and the per capita consumption of cigarettes with an enterprising attempt to recruit new smokers-particularly young people and women.

Adolescent↗
PubMed1988

Health effects due to occupational exposure to cobalt blue dye among plate painters in a porcelain factory in Denmark.

Forty-six plate painters, heavily exposed to cobalt blue dye, took part in this cross-sectional study, and 51 top-glaze painters served as the referents. The study comprised a questionnaire, a health examination, a lung function test, and the determination of the blood and urinary cobalt levels. The plate painters were examined twice, at the end of a workfree period and after resuming work. More plate painters complained of irritation from the mucous membranes in the mouth and throat, cough, and expectoration than the referents. The symptoms increased after the plate painters resumed work. The cobalt level of the plate-painting group after six weeks off work was twice as high in the blood and five times higher in the urine than the corresponding values of the reference group. After the plate painters resumed work, the blood and urinary levels increased approximately 4 and 15 times, respectively. Increased airflow resistance was found in the plate group when compared with the referents, and signs of small airway obstruction increased after the plate painters resumed work. The pulse rate was higher among the plate painters, and minor changes in the red blood cell picture were observed. None of these adverse health effects were associated with the cobalt levels in the blood or urine.

Air Pollutants, Occupational↗