Physicians' judgments of the risks of cardiac procedures. Differences between cardiologists and other internists.

OBJECTIVES: The authors compared judgments of the population risks of invasive cardiac procedures made by cardiologists and other internal medicine physicians. Our main hypotheses were that cardiologists' judgments would differ from those made by the other physicians and that cardiologists' judgments would be more accurate than those of other physicians. METHODS: This was a cross-sectional survey of senior staff and physician-trainees at two teaching hospitals affiliated with a US medical school, Emergency Department physicians at a community hospital in the same metropolitan area, and senior staff and trainees at two teaching hospitals affiliated with a UK school. Judgments of the risks of severe morbidity and death due to Swan-Ganz catheterization, cardiac catheterization, percutaneous coronary angioplasty, and coronary artery bypass grafting were assessed. RESULTS: Nineteen cardiologists judged the risks of severe morbidity due to all procedures and the risks of death due to all procedures except coronary artery bypass grafting to be significantly lower than did the 78 other internists. Cardiologists more frequently made accurate judgments of the rates of morbidity and death due to cardiac catheterization than did the other internists; other internists more frequently made accurate judgments for the rates of morbidity due to Swan-Ganz catheterization. CONCLUSIONS: Disagreements about the risks of procedures may arise from a paucity of published data, or from an over-supply of confusing data.

Clinical trials and clinical practice: do doctors use the same criteria to judge outcome?

AIMS: The results of clinical trials often seem to have little influence on the practice of individual doctors. This could be because trial information is presented in the style of a scientific experiment which cannot often be clearly related to the context of everyday patient care. We tested the hypothesis that such framing effects would cause doctors to assess the clinical significance of treatment outcomes differently when presented as clinical trial results rather than as individual patient data. METHODS: Fourteen rheumatologists independently reviewed the same 50 sets of data obtained from patients with rheumatoid arthritis. The data consisted of 10 commonly used clinical and laboratory variables measured before and after a period of treatment. The same data were presented in two formats on two separate occasions. The patient data format was a collection of typed sheets attributing each set of results to an individual patient. The clinical trial format was a professionally printed and bound booklet in which each set of results was laid out as summary results of a small uncontrolled clinical trial. Doctors judged the degree of improvement or deterioration and its clinical importance for each data set for both formats. These changes were converted into units of 'Clinical Importance'. RESULTS: Although some statistically significant differences emerged in the individual doctors' judgements between the formats none of these was of a clinically important size. The median of the mean trial--patient difference between the formats for all 14 doctors was 0.035 units of clinical importance [95% CI -0.244 to 0.074]. CONCLUSIONS: This evidence does not support the hypothesis that framing effects are a major cause of the failure of clinical trials to influence clinical practice.

Clinical judgment analysis.

Judgement is central to the practice of medicine and occurs between making clinical observations and taking clinical decisions. Clinical judgment analysis has developed as a method of making statistically firm models of doctors' judgments. Computed models reveal the differential importance attached to items of clinical, social, or other data which are determinants of clinical decisions. These models can both reveal the causes of conflicts of judgment and may help resolve them in a way that unaided discussion cannot. Revealing experts' models to students speeds learning of diagnostic skills. Clinical judgment analysis offers a method of probing the judgments not just of students and doctors but also of patients who have shown systematic differences in their perceptions of risk and benefit. The power and relevance of clinical trials can be improved by the consistent application of judgment policies generated from both the trialists and those who will use their results.

How can we design trials to detect clinically important changes in disease severity?

1. Forty-eight British rheumatologists judged the change in disease activity in 50 sets of patient data drawn from life and presented as 'paper patients'. Each set comprised two values, recorded a year apart, for 10 commonly measured clinical variables. Doctors recorded the size of improvement or deterioration on a visual analogue scale (VAS) and whether the change was clinically important or not. 2. Clinical judgement policies were modelled using linear regression of the clinical variables on the VAS score. 3. Doctors showed little agreement over which patients had improved and which had not. Possible reasons could be discovered by inspecting their judgement policies. 4. The weights attributed to the clinical variables differed considerably between doctors. Furthermore weights the doctors believed they attached to the variables frequently differed from the weights in the regression models. 5. These models could be used to calculate the smallest change required in any clinical variable before it would be considered clinically important. However, the size of such changes was often outside the observed clinical range suggesting that the use of single outcome variables is unrealistic. 6. The modelling procedure described can be applied during the planning stage of the trial to participating physicians, patients, health economists or any other group having an interest in the results. The models themselves can then be used to reach a consensus policy for judging what is a successful outcome. This may be expressed as a linear combination of specific outcome measures. Its use may improve the power of clinical trials and the relevance of their results.

Residual renal function in hemodialysis patients may protect against hyperaluminemia.

We investigated 106 home hemodialysis patients whose mean [+/- SEM] serum aluminum (Al) concentration was 60.9 +/- 4.1 micrograms/liter. Serum Al concentration was inversely related to daily urine output (r = -0.52, P less than 0.001). Urine volume and measurements of Al exposure were included in a multivariate analysis of serum Al concentration in the 62 patients whose urine output was greater than 10 ml/day. The multiple correlation coefficient (r) was 0.70 (P less than 0.001) and the percentage contributions to r2 (indicating the relative importance of each factor) were: urine output 57%, oral Al intake 36%, total dialysis hours 7%. The additional contribution from cumulative water Al was negligible. In a subgroup of 26 patients with a urine output exceeding 10 ml/day, urinary Al excretion averaged 15.4 micrograms/day, and renal Al clearance and serum Al concentration were inversely related (r = -0.69, P less than 0.001). We conclude that Al-containing phosphate binders were a more important source of Al than was dialysate in these patients and that residual renal function can reduce the severity of hyperaluminemia in hemodialysis patients.

The interaction between chronic oral slow-release theophylline and single-dose intravenous erythromycin.

Eight volunteers were each given 300 mg of erythromycin lactobionate by i.v. infusion over 15 min in the presence and absence of chronic dosing with slow-release theophylline. Pharmacokinetic profiles were obtained for theophylline in the presence and absence of erythromycin and for erythromycin in the presence and absence of theophylline. A very small, clinically unimportant, but statistically significant increase occurred in mean (+/- S.E.M.) serum theophylline concentration from 4.9 +/- 0.3 mg/l to 5.2 +/- 0.3 mg/l in the presence of erythromycin (P = less than 0.01). The theophylline pharmacokinetic parameters did not change significantly. The only changes in erythromycin pharmacokinetics were an increase in the renal excretion (0-12 h) from 5.5 +/- 4.0 mg to 11.2 +/- 6.0 mg (P less than 0.03) and an increase in renal clearance (0-2 h) from 9.0 +/- 6.0 ml/min to 21.6 +/- 15 ml/min (P less than 0.05) in the presence of theophylline.

Teaching and learning about terminal care.

Because the same three teachers at the London Hospital Medical College both taught and examined students over an 11-year period it was possible to compare what was taught with what was recalled at examinations. The results suggest that aspects of terminal care vary greatly in their perceived importance, at least as measured by their recall and selection for presentation in the final examination. Most aspects of the taught material increased their penetration into the students' recall over the 11 years. There is evidence that the caring aspects are stressed more by women; this difference was less for descriptions of pain, and absent from accounts of the pharmacology of analgesic drugs.

Gastrointestinal side effects after intravenous erythromycin lactobionate.

Ten healthy normal volunteers received an intravenous infusion of erythromycin lactobionate over 60 min to a total dose of 800 mg (n = 9), and 524 mg (n = 1). Blood samples were collected at 10 min intervals for 100 min and gastric contents aspirated, via a nasogastric tube, from pre-dose to 105 min after start of infusion. Incidence and severity of three gastrointestinal symptoms (nausea, stomach discomfort and feelings of hunger), two CNS symptoms (dizziness and faintness) and a 'control' symptom (back pain) were measured using 100 mm visual analogue scales. Rate of infusion and plasma erythromycin concentration correlated with nausea (P less than 0.001) and stomach discomfort (P less than 0.001); plasma erythromycin concentration was also correlated with dizziness (P less than 0.05). Concentrations of active erythromycin in the aspirate were pH dependent. In one subject the concentration of erythromycin in the aspirate exceeded that in the plasma by 100 fold. Bile staining of samples containing the highest levels of microbiologically active erythromycin makes the origin of the erythromycin in these samples uncertain.

Inability of rheumatologists to describe their true policies for assessing rheumatoid arthritis.

Eighty nine British and Australian rheumatologists took part in a study to discover how accurately they could describe their procedures for measuring disease severity in rheumatoid arthritis. The relative importance they attached to different clinical and laboratory variables showed a very wide variation, and these stated policies were generally poor at predicting their actual judgments when assessing 'paper patients' (r2 = 39%). Policies based on equal weighting of all variables, while also poor predictors (r2 = 41%), were nevertheless superior to their stated policies for 49 respondents. Policies calculated by judgment (linear regression) analysis were much more successful predictors (R2 = 73%). Unhurried, detailed interviews with four experienced rheumatologists provided carefully considered statements of assessment policy, but these also were poor predictors of routine assessments of outpatients (r2 = 34%) compared with policies calculated by clinical judgment analysis, even when these were applied to new data (R2 = 88%).

Antibiotics for otitis media: can we help doctors agree?

Wide variations in antibiotic prescribing for otitis media have suggested the need to discover the causes of the differences and help doctors reach agreement. Simulated cases--in the form of written clinical data extracts based on real patients--were used to study the diagnostic and prescribing behaviour of a group of six general practitioners. Clinical judgement analysis was used to model the way in which doctors diagnosed otitis media and their policy for using antibiotics. Most doctors performed consistently and their judgements could be fitted well to models using a small number of symptoms and signs. These models often differed from the policy they believed they were operating. This information was used as process feedback in a group discussion to help improve agreement within the practice on the management of otitis media. Some of the variation in behaviour observed at the start of the study was reduced by significant changes in that of the trainee. Other doctors changed little and some were sceptical of the validity of the experimental methods. The prospects for and difficulties of this type of analysis are discussed.

Clinical judgment in rheumatoid arthritis. III. British rheumatologists' judgments of 'change in response to therapy'.

A realistic analysis of the criteria used by rheumatologists in evaluating the progress of patients suffering from rheumatoid arthritis must be based on actual clinical judgments rather than on expressed opinions. A randomly selected 15% sample of British rheumatologists (48) recorded judgements on the progress of 50 'paper' patients, based on data taken from actual patients participating in clinical trials. The rheumatologists differed markedly in their assessments of the progress of disease, with serious disagreements even when only 'clinically important' changes were considered. Some clinicians showed little consistency in their judgments of duplicate cases. Multiple regression analysis of the patient data in relation to the disease assessments provided a model of each clinician's judgment policy. These judgment policy models showed that the differences in clinical assessment were greater than could be explained by the inconsistent application of similar assessment policies, and were a consequence also of differences in the underlying judgment policies themselves. Judgments related more closely to changes in ESR and other process measures than to changes in functional ability.

Clinical judgment in rheumatoid arthritis. I. Rheumatologists' opinions and the development of 'paper patients'.

Opinions about the importance of various measures of disease activity in rheumatoid arthritis gathered from a survey of 20% of British rheumatologists showed a wide diversity for all clinical variables. 'Paper patients' have been developed as a method of investigating actual clinical decisions rather than expressed opinions. Assessments based on 'paper patients' correlate highly (r = +0.901) with those made on the equivalent real patients when seen in person.

Clinical judgment in rheumatoid arthritis. II. Judging 'current disease activity' in clinical practice.

Two rheumatologists made judgments about 'current disease activity' in real patients and 'paper patients' with rheumatoid arthritis. Analysis of each set of judgments provides a model of judgment policy which contains only 3 clinical variables but explains over 94% of the variance in judgments. The judgment policy models differ markedly from each other and from the clinicians' own perceptions of their behaviour. Judgment policy modelling offers a means of improving co-ordination between clinical investigators within and between centres.

Clinical judgement analysis--practical application in rheumatoid arthritis.

Clinical judgment analysis has been used to investigate differences in assessing disease activity in rheumatoid arthritis. Rheumatologists as a group do not adopt a single underlying policy for the assessment of changes in disease activity; each has his or her own approach to such judgements. Some rheumatologists are inconsistent in applying their judgment policies, leading to disagreements even when underlying policies are similar. Having identified these problems of assessment, clinical judgement analysis may be employed to reduce clinical disagreement and to improve coordination and consistency between rheumatologists in different centres during clinical investigations.

Controlled trial of calcitriol in the prevention of bone disease in haemodialysed patients.

Seventy-six patients receiving regular haemodialysis, without biochemical or radiological evidence of renal osteodystrophy, entered a five-year double-blind placebo-controlled trial of calcitriol (1,25-dihydroxycholecalciferol) in the prevention of bone disease. Significantly more patients on placebo developed bone disease as judged by a sustained elevation of plasma alkaline phosphatase or the development of sub-periosteal erosions on hand radiographs. Serum parathyroid hormone fell significantly in the patients receiving calcitriol and was significantly lower than in patients receiving placebo. It is concluded that calcitriol delays and may prevent the development of metabolic bone disease in patients receiving regular haemodialysis therapy.