Biomedical subjects

M Abrahamowicz

Publications and source records attributed to M Abrahamowicz.

At least 37 records · Page 2Linked to original sources

PubMed1997

Factors associated with growth of extremely premature infants during initial hospitalization.

OBJECTIVE: To quantify the factors associated with growth of very small premature infants during initial hospitalization. POPULATION: Study patients were 109 infants who were appropriate for gestational age, weighed <1000 g at birth, and were fed intravenous hyperalimentation then calcium-supplemented 81-kcal preterm formula according to a protocol. ANALYSIS: Multiple regression analysis was performed for periods of 0 to 56, 0 to 14, and 15 to 56 days of age. Growth was determined as change in weight during the period. Variables assessed in the initial model were caloric intake, protein intake, respiratory support duration, patent ductus arteriosus, dexamethasone use, infection, birth weight ratio (weight divided by expected intrauterine weight for gestation), gestational age, sex, calendar time from study start, maternal betamethasone administration, and necrotizing enterocolitis. For the 0 to 14-day period, maximum oxygen requirement for respiratory distress syndrome replaced respiratory support duration, and 5-minute Apgar score was added, whereas dexamethasone and necrotizing enterocolitis were deleted. RESULTS: Mean change in weight was 785 g for 0 to 56 days, -16 g for 0 to 14 days, and 770 g for 15 to 56 days. Mean weight was 94% (13 SD) of mean intrauterine at birth, 73% (10 SD) at 14 days, and 73% (12 SD) at 56 days. Regression models explained 85%, 43%, and 80%, respectively, of variation in growth. Of the initial variables assessed, the following were the independent prognostic determinants of growth. There was a positive association with caloric intake at 0 to 56 days and 15 to 56 days, and with protein intake at 0 to 14 days. Negative associations were found for birth weight ratio and gestational age at 0 to 56 and 0 to 14 days. Respiratory support duration was negatively associated at 15 to 56 days, and dexamethasone was negatively associated at 0 to 56 and 15 to 56 days. Formulas to predict growth were established from the final regression models. CONCLUSION: The growth failure in appropriate-for-gestational-age, <1000-g birth weight infants can be related in part to dexamethasone use and respiratory support duration. Increasing caloric intake and early protein intake improves growth. However, for the majority of these patients, early losses are not corrected completely by 56 days using currently recommended intakes.

Dexamethasone↗

PubMed1996

Do too many cooks spoil the broth? Multiple physician involvement in medical management of elderly patients and potentially inappropriate drug combinations.

OBJECTIVES: To determine (a) whether the risk of a potentially inappropriate drug combination (PIDC) increases with the number of physicians involved in the medical management of an elderly patient and (b) whether the risk of a PIDC is reduced if a patient has a single primary care physician or a single dispensing pharmacy, or both. DESIGN: Cross-sectional retrospective provincial database study. PARTICIPANTS: A regionally stratified random sample of 51,587 elderly medicare registrants in Quebec who (a) visited at least one physician in 1990, (b) were not living in a health care institution for the entire year and (c) had been dispensed at least one prescription for a cardiovascular drug, a psychotropic drug or a nonsteroidal anti-inflammatory drug (NSAID). OUTCOME MEASURES: Information on all physician visits and drugs dispensed during 1990. Physician claims were used to identify the number of physicians involved in a patient's management and whether the patient had one primary care physician. Prescription claims were used to identify the number of PIDCs, prescribing physicians and dispensing pharmacies. RESULTS: The prevalence of PIDCs ranged from 4.0% (among those in the NSAID group) to 20.3% (among those in the psychotropic drug group). Of the PIDCs identified, 17.6% to 25.8% resulted from contemporaneous prescribing by different physicians. The number of prescribing physicians was the most important risk factor for a PIDC in all drug groups (odds ratio [OR] 1.44 to 1.71). The presence of a single primary care physician lowered the risk for cardiovascular and psychotropic PIDCs (OR 0.70 and 0.79 respectively) but not for NSAID PIDCs (OR 0.94). The use of a single dispensing pharmacy lowered the risk of a PIDC in all drug groups (OR 0.68 to 0.79). CONCLUSION: The greater the number of physicians prescribing medications for an elderly patient, the greater is the risk that the patient will receive a PIDC. A single primary care physician and a single dispensing pharmacy may be "protective" factors in preventing PIDCs.

Aged↗

PubMed1996

Laboratory tests as predictors of disease exacerbations in systemic lupus erythematosus. Why some tests fail.

OBJECTIVE: To evaluate whether changes in laboratory test values are either simultaneous with or precede disease exacerbations in patients with systemic lupus erythematosus (SLE). METHODS: At 9, 6, and 3 months preceding a flare in disease activity (defined as a rise of > or = 6 points in the modified SLE Disease Activity Index), laboratory tests were performed to measure patients' hematocrit levels, white blood cell, lymphocyte, and platelet counts, erythrocyte sedimentation rate, C1q binding, DNA binding, and levels of C3 and C4. Flares were classified as either present or absent, and were divided into renal, vasculitic, central nervous system, skin, serosal, and musculoskeletal subgroups. The predictive patterns were 1) the simultaneous change in the test value from the mean of 9, 6, and 3 months preceding a flare to the time of the flare; 2) the gradual change, following a linear time trend, in test results for the same time points; and 3) the change from the mean of 9 and 6 months to 3 months preceding a flare, as a measure of predictive ability. These analyses used repeated-measures analysis of variance models. Multiple linear regression was used to study the cross-sectional association of average-over-time differences in test results with patients' flare subgroup. RESULTS: Among 202 patients with SLE (median followup 86.5 months), 83 flares occurred in 53 patients. Of 189 statistical contrasts performed, only 14 were significant (versus 10 expected), and the differences were of minor importance. Nonetheless, evaluation of all test results over each patient's observed disease course revealed significant differences between selected test values in association with specific types of flare. CONCLUSION: Fluctuations in laboratory test values are poor predictors of disease exacerbations in SLE. Cross-sectional evaluation of some test results revealed differences at the time of flare for those patients who were destined to have different types of flares, because these values differed over the entire study period. This pattern explains the frequent cross-sectional association of disease activity with laboratory test results, and the inconsistent association of flares with recent changes in test values.

Adolescent↗

PubMed1996

The Quebec Back Pain Disability Scale: conceptualization and development.

The Quebec Back Pain Disability Scale is a new measure of functional disability for patients with back pain. Functional disability was operationalized in terms of perceived difficulty associated with simple physical activities. The content of the scale was developed in several stages, including a literature review, two studies seeking the opinions of patients and experts, pilot testing, and a large, longitudinal study of back pain patients. Forty-eight disability items were extensively studied using standard methods such as test-retest reliability, item-total correlations, and factor analysis, as well as modern techniques based on item response theory. Items that were highly effective in discriminating between different levels of disability were selected for the final, reduced scale. The scale has 20 items, representing six empirically derived categories of activities affected by back pain. Measurement properties of this instrument have been previously discussed.

Activities of Daily Living↗

PubMed1996

Incidence of and risk factors for delirium among psychiatric inpatients.

OBJECTIVE: The presence and effects of delirium among psychiatric patients are not well understood. This study investigated incidence rates and risk factors for delirium among hospitalized psychiatric patients. METHODS: The charts of 199 patients admitted over a one-year period to a tertiary care teaching hospital were retrospectively reviewed. Demographic and medication variables were analyzed using multiple logistic regression. Delirium was diagnosed retrospectively using DSM-III-R criteria. RESULTS: The overall incidence of delirium in the study sample was 14.6 percent. Delirium was most common among patients with schizophrenia and bipolar disorder; patients with bipolar disorder had the highest incidence (35.5 percent). Only 48 percent of delirious patients were actually recognized as having delirium at the time it occurred. Antiparkinsonian medications were the only medications significantly associated with delirium; lithium was not an independent risk factor. Older age was the only significant demographic risk variable. The hospital stays of patients with delirium were 62.1 percent longer than those of patients without delirium. CONCLUSIONS: Patients with bipolar disorder appeared to be at higher risk for developing delirium, whether or not lithium was used in treatment. This finding may reflect an inherent predisposition to delirium among these patients. Alternatively, the combination of medications used in treating patients with bipolar disorder may be a risk factor.

Adult↗

PubMed1996

Randomized controlled trial of artesunate plus tetracycline versus standard treatment (quinine plus tetracycline) for uncomplicated Plasmodium falciparum malaria in Brazil.

A triple-blind, randomized, clinical trial was undertaken in a Brazilian Amazon region to compare the effectiveness of oral artesunate (seven days, total dose = 0.75 g) plus tetracycline (seven days, total dose = 10.5 g) (AT) and oral quinine (three days, total dose = 6 g) plus tetracycline (seven days, total dose = 10.5 g) (QT) against uncomplicated Plasmodium falciparum malaria. Effectiveness was assessed by cure rates (World Health Organization [WHO]) and parasite clearance at day 2. Patients were randomized, 88 to each group. The groups had similar baseline clinical characteristics. The incidence of side effects was much higher in the QT group (82%) than in the AT group (50%) (P < 0.001). Cure rates were similar: 80% in the AT group and 77% in the QT group (P = 0.68). Parasitemia (by day 2) cleared faster in the AT group than in the QT group (98.5% versus 47.6%, respectively; P < 0.001). These results indicate that the combination of artesunate plus tetracycline is effective in the treatment of uncomplicated falciparum malaria and may provide a useful alternative to other treatment regimens.

Adolescent↗

PubMed1996

Routine immunologic tests in systemic lupus erythematosus: is there a need for more studies?

OBJECTIVE: To evaluate the sensitivity, specificity, and likelihood ratios of anti-dsDNA, C3, C4, and Clq binding tests for predicting flares in systemic lupus erythematosus (SLE) and to evaluate the conflicting results reported in the recent literature. METHODS: Test results from 9 to 3 months preceding 83 flares among 53 patients from a cohort study of 202 patients with SLE were assessed for their ability to predict renal and nonrenal flares and all flares combined. A flare was defined as a 6 point rise in a modified SLE Disease Activity Index. RESULTS: For all 4 tests, sensitivity approximated 50% and specificity was less than 75%. For anti-dsDNA, Clq binding, and C4, both positive and negative likelihood ratios were close to 1.0, suggesting little clinical value for routine testing. For C3, likelihood ratios for a positive test approximated 2.0, meeting the minimal level for clinical significance. Review of previous studies suggested that sample size, the use of a standardized disease activity measure to define a flare, the severity of the flare, and the study duration could not explain the discrepant results among studies. The 2 studies with testing every 4 to 6 weeks found that a rising anti-dsDNA predicted flares, while those with less frequent testing did not. CONCLUSION: While our study provided no major support for routine testing with anti-dsDNA, C3, C4, or Clq binding, additional longitudinal studies are needed to assess monthly testing of anti-dsDNA as a predictor of flare in SLE.

Adult↗

PubMed1995

Lack of effect of aspirin in asymptomatic patients with carotid bruits and substantial carotid narrowing. The Asymptomatic Cervical Bruit Study Group.

OBJECTIVE: To determine the effectiveness of aspirin in preventing ischemic events in patients with asymptomatic carotid stenosis. DESIGN: Double-blind, placebo-controlled trial. SETTING: University-affiliated hospitals. PATIENTS: 372 neurologically asymptomatic patients with carotid stenosis of 50% or more in at least one artery as determined by luminal diameter reduction on duplex ultrasonography. INTERVENTION: Patients were randomly assigned to receive either enteric coated aspirin, 325 mg/d, or identically appearing placebo. Duration of therapy was 2.0 years for the aspirin recipients and 1.9 years for the placebo recipients. OUTCOME MEASURES: Patients were scheduled for a clinical examination every 6 months for assessment of the occurrence of any clinical event in the composite end point, which consisted of transient ischemic attack, stroke, myocardial infarction, unstable angina, or death. RESULTS: At baseline, the 188 patients receiving aspirin and the 184 patients receiving placebo had similar demographic, ultrasonographic, and laboratory characteristics. The median duration of follow-up was 2.3 years. The annual rate of all ischemic events and death from any cause was 12.3% for the placebo group and 11.0% for the aspirin group (P = 0.61). The Cox proportional hazards analysis yielded an adjusted hazard ratio (aspirin-placebo) of 0.99 (95% CI, 0.67 to 1.46; P = 0.95). The annual rates for vascular events only were 11% for the placebo group and 10.7% for the aspirin group (P = 0.99). The multivariate analysis yielded a hazard ratio of 1.08 (CI, 0.72 to 1.62; P = 0.71). CONCLUSION: Aspirin did not have a significant long-term protective effect in asymptomatic patients with high-grade (> or = 50%) carotid stenosis.

Aged↗

PubMed1995

Do doctors accurately assess coronary risk in their patients? Preliminary results of the coronary health assessment study.

OBJECTIVE: To evaluate the ability of doctors in primary care to assess risk patients' risk of coronary heart disease. DESIGN: Questionnaire survey. SETTING: Continuing medical education meetings, Ontario and Quebec, Canada. SUBJECTS: Community based doctors who agreed to enroll in the coronary health assessment study. MAIN OUTCOME MEASURE: Ratings of coronary risk factors and estimates by doctors of relative and absolute coronary risk of two hypothetical patients and the "average" 40 year old Canadian man and 70 year old Canadian woman. RESULTS: 253 doctors answered the questionnaire. For 30 year olds the doctors rated cigarette smoking as the most important risk factor and raised serum triglyceride concentrations as the least important; for 70 year old patients they rated diabetes as the most important risk factor and raised serum triglyceride concentrations as the least important. They rated each individual risk factor as significantly less important for 70 year olds than for 30 year olds (all risk factors, P < 0.001). They showed a strong understanding of the relative importance of specific risk factors, and most were confident in their ability to estimate coronary risk. While doctors accurately estimated the relative risk of a specific patient (compared with the average adult) they systematically overestimated the absolute baseline risk of developing coronary disease and the risk reductions associated with specific interventions. CONCLUSIONS: Despite guidelines on targeting patients at high risk of coronary disease accurate assessment of coronary risk remains difficult for many doctors. Additional strategies must be developed to help doctors to assess better their patients' coronary risk.

Clinical Competence↗

PubMed1995

The Quebec Back Pain Disability Scale. Measurement properties.

STUDY DESIGN: The Quebec Back Pain Disability Scale is a 20-item self-administered instrument designed to assess the level of functional disability in individuals with back pain. The scale was administered as part of a larger questionnaire to a group of 242 back pain patients. Follow-up data were obtained after several days and after 2 to 6 months. OBJECTIVES: The goal of this study was to determine whether the Quebec scale is a reliable, valid, and responsive measure of disability in back pain, and to compare it with other disability scales. SUMMARY OF BACKGROUND DATA: A number of functional disability scales for back pain are being used, but their conceptual validity is uncertain. Unlike most published instruments, the Quebec scale was constructed using a conceptual approach to disability assessment and empirical methods of item development, analysis, and selection. METHODS: The authors calculated test-retest and internal consistency coefficients, evaluated construct validity of the scale, and tested its responsiveness against a global index of change. Direct comparisons with the Roland, Oswestry, and SF-36 scales were carried out. RESULTS: Test-retest reliability was 0.92, and Cronbach's alpha coefficient was 0.96. The scale correlated as expected with other measures of disability, pain, medical history, and utilization variables, work-related variables, and socio-demographic characteristics. Significant changes in disability over time, and differences in change scores between patients that were expected to differ in the direction of change, were found. CONCLUSIONS: The Quebec scale can be recommended as an outcome measure in clinical trials, and for monitoring the progress of individual patients participating in treatment or rehabilitation programs.

Adolescent↗

PubMed1995

Small changes in outpatients lupus activity are better detected by clinical instruments than by laboratory tests.

OBJECTIVE: To evaluate and compare responsiveness of laboratory and clinical measures over 4 months in outpatient systemic lupus erythematosus (SLE). METHODS: We studied 23 patients with SLE at monthly intervals during 4 mo and collected demographic data, prednisone dose, global patient and physician assessment of disease activity on 10 cm visual analog scales (VAS), scores on 3 clinical measures of lupus disease activity [SLE disease activity index (SLEDAI), SLE activity measure (SLAM), lupus activity index (LAI)], and results of 5 routine laboratory tests [erythrocyte sedimentation rate (ESR), anti-dsDNA, C3, C4, circulating immune complexes]. We calculated correlations between a particular measure and our gold standard (physician's VAS) for individual patients and pooled this information using a novel application of the meta-analytic approach. RESULTS: The range of disease activity by patient and physician VAS varied from inactive to moderately active> Change in patient global assessment and all 3 clinical measures showed significant positive correlations with change in physician VAS (p < 0.05). Change in ESR, anti-dsDNA, or level of C3, C4, or circulating immune complexes did not correlate with change in physician VAS. CONCLUSION: Clinical measures of disease activity in SLE are more responsive to small changes than traditional laboratory tests. All 3 clinical measures appeared to perform equally well. At least one SLE disease activity measure should be used in SLE trials. The new analytic method will likely be of value in similar evaluations of responsiveness in other diseases.

Adult↗

PubMed1994

Life expectancy following dietary modification or smoking cessation. Estimating the benefits of a prudent lifestyle.

OBJECTIVE: To evaluate the maximum benefits of dietary modification or smoking cessation to the life expectancy of North American adults. DESIGN: Using a computer model, we estimated the change in life expectancy for men and women following risk factor modification. We then estimated the total number of adults who would be targeted by national guidelines and the total person-years of life that would be saved. PATIENTS: Men and women aged 30 to 74 years who were free of coronary heart disease. INTERVENTIONS: Smoking cessation or serum cholesterol-reducing diets with 8% to 10% saturated fat and 240 to 300 mg of daily cholesterol, respectively. RESULTS: On average, dietary modification would reduce serum cholesterol levels from 0.45 mmol/L (17.4 mg/dL) to 0.75 mmol/L (29.1 mg/dL) in men and 0.12 mmol/L (4.6 mg/dL) to 0.55 mmol/L (21.4 mg/dL) in women, thereby increasing life expectancy by 0.03 to 0.4 year and 0.01 to 0.16 year, respectively. Smoking cessation would increase life expectancy from 2.59 to 4.43 years among men and from 2.6 to 3.68 years among women. Among adult Canadians, dietary modification would save 373,000 to 683,000 person-years of life. The majority of these benefits would occur among men who start dieting at ages 30 to 59 years. Smoking cessation would add more than 4 million person-years of life to the Canadian population. The relative impact of either intervention among American adults would be similar to these Canadian estimates. CONCLUSIONS: Younger men, aged 30 to 59 years, might live slightly longer after dietary change, but among women and older men the average benefits would be negligible. The benefits of smoking cessation are more uniform across age and sex and are substantially greater than those predicted for dietary change.

Adult↗

PubMed1994

Questionable prescribing for elderly patients in Quebec.

OBJECTIVE: To estimate the prevalence of questionable and rational high-risk prescribing among elderly people of the three drug groups most commonly implicated in drug-related illness: cardiovascular drugs, psychotropic drugs and nonsteroidal anti-inflammatory drugs (NSAIDs). DESIGN: Retrospective prevalence study; all prescription and billing records for the period Jan. 1 to Dec. 31, 1990, for the study sample were retrieved from the relevant provincial databases of the Régie de l'assurance-maladie du Québec. SETTING: Quebec. PARTICIPANTS: Regionally stratified random sample of 63,268 elderly medicare registrants who made at least one visit to physician in 1990 and were not living in a health care institution for the entire year. MAIN OUTCOME MEASURE: Prescription information was examined for three types of high-risk prescribing: rational and questionable drug combinations, excessive treatment duration and drugs relatively contraindicated for use in elderly people. RESULTS: Overall, 52.6% of the patients experienced one or more events of high-risk prescribing, and 45.6% experienced at least one that was questionable. High-risk prescribing was most prevalent for psychotropic drugs, and questionable prescribing was more frequent than rational prescribing in this drug group. An estimated 30.8% of the total elderly population in Quebec received benzodiazepines for more than 30 consecutive days, 12.9% received a long-acting benzodiazepine, and 13.0% received a questionable high-risk psychotropic drug combination. The prevalence of high-risk prescribing was higher among the women than among the men and increased with age until 75 to 84 years. There were significant unexplained differences between regions in the regional prevalence of high-risk prescribing, particularly of psychotropic drugs. CONCLUSION: The prevalence of questionable high-risk prescribing, especially of psychotropic drugs, is substantial among elderly people. This may be a potentially important and avoidable risk factor for drug-related illness in elderly people.

Age Factors↗

PubMed1994

The time-dependence of long-term prediction in lupus nephritis.

OBJECTIVE: To assess the clinical, laboratory, and renal biopsy predictors of long-term outcome in lupus nephritis and to investigate the time-dependence of these predictors. METHODS: Eighty-seven lupus nephritis patients were studied retrospectively for the outcomes renal failure and fatality due to renal involvement. In addition to a conventional Cox model analysis, a new generalized time-dependent analytic approach was developed and used to assess the time-dependence of a predictor variable's importance. RESULTS: The mean followup time was 11.9 years. Renal failure (n = 19) was significantly predicted by measures of renal function (abnormal serum creatinine levels, proteinuria, duration of prior renal disease) and immunologic activity (elevated DNA binding, hypocomplementemia, and thrombocytopenia), by overall lupus disease activity measures (le Riche index, Lupus Activity Criteria Count), and by the activity index, the tubulointerstitial index, and the amount of subepithelial deposits on renal biopsy. In general, the laboratory predictors were significantly better prognostic markers in the early years after biopsy, the disease activity measures were best in the later years, and the biopsy variables were significant predictors over the entire observation period. In contrast to the renal failure outcome, the best predictors for death not directly related to lupus nephritis (n = 17) were the extent of comorbid diseases (principally vascular diseases), older age, and the chronicity index. All three predicted well over the extended observation period. CONCLUSION: The major predictor variables for renal outcomes and nonrenal outcomes are distinct. The time-dependence of the predictive ability of some variables may be important in managing individual patients. The new generalized time-dependent analytic technique may have widespread application in studies to identify prognostic factors for established disease or risk factors for the development of disease.

Adolescent↗

PubMed1994

Quantitative sweat testing using acetylcholine for direct and axon reflex mediated stimulation with silicone mold recording; controls versus neuropathic diabetics.

Sweat glands were stimulated by iontophoresed acetylcholine (ACh). Using a two-chamber capsule, one group of sweat glands was stimulated directly by ACh, and another stimulated indirectly via axon reflexes. Sweat droplets were recorded with a silicone mold and counted by a dissecting microscope and a computerized scanner. Responses from 32 diabetics with generalized somatic peripheral neuropathy were compared with 32 controls. Counting sweat droplets by computerized scanning was more accurate than by microscope. The numbers of droplets, their total areas, and mean areas were all larger in the direct response. Counts of droplet numbers was more diagnostically useful than measuring the total area and the mean areas of the droplets. There was a high correlation between droplet numbers of the direct and the indirect sweat responses. Droplet number counts of the direct response had a slightly higher diagnostic yield than those of the technically more complicated indirect response: for a specificity of 95%, the direct response had a sensitivity of 55%, the indirect being 50%.

Acetylcholine↗

PubMed1994

The feasibility and value of using patient satisfaction ratings to evaluate internal medicine residents.

OBJECTIVE: To determine the feasibility and value of using patient satisfaction ratings to evaluate the physician-patient relationship skills of medical residents. DESIGN: A cross-sectional survey was used to collect patient satisfaction information for medical residents from all patients attending the out-patient teaching clinics over a three-month period. The feasibility of patient rating was assessed by evaluating the reliability of resident satisfaction scores and potential sources of bias in rating. The value of using this method was assessed by evaluating the proportion of variance in ratings attributable to residents, the prevalence of residents with ratings substantially below average, and the effect of training on patient satisfaction. SETTING: The medical clinics of two teaching hospitals at McGill University. PARTICIPANTS: 91 medical residents and clinical clerks, 1,003 patients, and 1,219 visit ratings. RESULTS: An average of 12.2 satisfaction ratings were collected per resident, providing a reliability of 0.56 (intraclass correlation) for resident satisfaction score. Adjustment for differences in patient populations would be necessary to obtain comparable scores among residents. Fifteen percent of the residents had a substantially greater proportion of poor and fair satisfaction ratings than the study average. Residents were responsible for a substantial proportion of the variance in clinic waiting time and patient satisfaction rating. Training appeared to have no effect on improving satisfaction scores, except among women residents. CONCLUSIONS: Patient satisfaction ratings provide valuable information about a resident's ability to establish an effective physician-patient relationship. However, the number of ratings required to obtain a reliable estimate of resident skill may limit the feasibility of using patient ratings as part of residency evaluation.

Adolescent↗

PubMed1993

Randomized discontinuation trials: utility and efficiency.

The randomized discontinuation trial (RDT) is a two-phase trial. In phase I all patients are openly treated with the medication being evaluated. In phase II, those who have responded are randomly assigned to continue the same treatment or switch to placebo. Usually, non-compliers and "adverse reactors" identified in phase I are excluded from phase II. To investigate the value of this design, we reviewed the advantages and limitations of discontinuation studies, and compared the RDT design to the classic randomized clinical trial design in terms of clinical utility and efficiency (sample size). A computer model was used to study the efficiency of the two designs under a broad range of assumptions. The RDT design is particularly useful in studying the effect of long-term, non-curative therapies, especially when the clinically important effect is relatively small, and the use of placebo should be minimized for ethical or feasibility reasons. However, its use is limited if the objective of an investigation is to estimate the magnitude of absolute treatment effects and toxic effects in the source population, or to evaluate a potentially curative treatment. Our results indicate that selecting responders prior to randomization has a very strong effect on the relative efficiency of the trial. Further improvement may be achieved by excluding non-compliers and adverse reactors. Under the assumptions tested in our model, the sample size required in phase II of an RDT was only 20-50% of that in a classic trial.

Computer Simulation↗

PubMed1993

Clinical tutor evaluation: a 5-year study by students on an in-patient service and residents in an ambulatory care clinic.

Medical students on an in-patient service and residents working in an ambulatory care clinic have regularly evaluated their clinical tutors over the 5 years 1985-1989. Both groups of raters reliably and predictably evaluated their tutors and both emphasize between-tutor comparisons more than actual rating values for individual tutors. Tutors active in both contexts regularly receive higher ratings from the medical students than from the residents. Mid-course feedback to tutors in the medical course had no impact on end-of-course ratings. In neither context did tutor ratings improve from one evaluation to the next. Both groups reliably discriminate between the teaching skills and the personality traits of individual tutors.

Ambulatory Care↗