Introduction. Surrogate marker responses are imperfect indicators of response to antiretroviral therapy in HIV. It is proposed that the area under the curve of surrogate marker response will be superior to peak response, or to that measured after a period of therapy. Methods. The database from a study of ritonavir in advanced HIV was used. Using logistic regression, the specificity of the surrogate marker level at baseline, change between baseline and at time points to week 16, peak response, and area under the curve of the response to week 16 and week 40 were determined. The predictive values, likelihood ratios and receiver operating characteristic curves were determined for those of highest specificity. Results. Specificities increased from baseline to week 16. Peak responses were inferior to time period surrogate marker changes, whereas the areas under the curve were comparable or better than the time period surrogate marker changes. The highest specificity at any time point was for the CD4 change at week 8 (55.90%), whereas the highest overall specificity was for the 16 week AUC for the CD4% (69.63%). However, the PPV, NPV, likelihood ratios and ROC curves demonstrated poor performance overall for these surrogate markers. Too few subjects had viral load testing for this marker to be assessed. Discussion. Within the limits of this study, it was demonstrated that the CD4 and CD4% were the surrogate markers most associated with clinical outcome, with the CD4% AUC to 16 weeks having the highest overall specificity and the week 8 CD4 having the greatest specificity for clinical use. However, all surrogate markers had specificities below 70%.

Background. The discharge summary is an important method of communicating information necessary for continuing patient care. Deficiencies in discharge summary content, accuracy, and timeliness are a common problem. To improve summaries, studies have assessed physician-in-training (housestaff) education, alteration of the summary format; and collating information within computer databases into a summary. The most promising technology for improving discharge summaries is the clinical database. Primary objective. To compare medical discharge summaries generated from a clinical database with those created by narrative letter dictation. Design. Randomized controlled trial assigning patients to database (DB) or dictated (dictated-random or D-R) summaries. This was preceded by a prospective cohort study where summaries for all patients were created by dictation (dictated-cohort or D-C group). Inclusion criteria and study setting. All patients admitted to and discharged alive from the general internal medicine service in a tertiary care teaching hospital. Intervention. For patients randomized to the DB group, housestaff completed forms capturing hospital and discharge information important for the discharge summary. This information was entered into a database along with portions of the admission history and physical-examination form. Information in the database was collated into a report to create a database discharge summary. For patients in the D-R and the D-C group, housestaff used narrative dictation to create summaries. (Abstract shortened by UMI.)

For patients with an acute myocardial infarction (AMI), the time from symptom onset to initiation of medical treatment is a critical determinant of outcome both for survival and for preservation of myocardial tissue. This is true because the effectiveness of thrombolytic therapy is, inversely related to time between onset of symptoms and initiation of therapy. Studies have shown that the time that patients take to decide to seek help accounts for most of the delay, a factor that has not improved despite efforts in education campaigns. Thus far, only two studies on delay time have been conducted in Canada. The study objective was to describe the delay time and investigate the factors associated with delay in response to symptoms of AMI in a Canadian setting. (Abstract shortened by UMI.)

The objective of this study was to systematically review the literature and to statistically summarize the evidence evaluating the efficacy of acute normovolemic hemodilution (ANH). Review of 1575 citations identified 24 prospective, randomized, controlled trails of ANH containing a total of 1216 patients. When all trials were pooled ANH reduced the likelihood of exposure to allogeneic blood and the total units of allogeneic blood transfused. Marked heterogeneity of the results was present and adverse events were incompletely reported. Subgroup analyses could not account for all heterogeneity noted in this overview. Under reporting of small trials with negative results was suspected. In trials using a protocol to guide perioperative transfusion, ANH failed to reduce either the likelihood of transfusion or the units administered. It is possible that experimental design bias in favor of reducing transfusion in the ANH group is in part responsible for the reported efficacy of this technique.

Background. Approximately four minion individuals in the United States are infected with hepatitis C virus (HCV). The relative risk of hepatocellular carcinoma (HCC) in patients with hepatitis C-related cirrhosis is at least 7 to 10 times that of the general population. The majority of patients who develop symptoms from HCC harbour tumors that are at an advanced and rapidly fatal stage. Screening has therefore been advocated as a mean of reducing cancer-related deaths. Objective. To determine, from a Canadian perspective, the cost-effectiveness of screening for HCC with biannual liver ultrasound (US) and alpha foetoprotein levels (AFP) in patients with well compensated hepatitis C-related cirrhosis. Methods. Decision analysis with a Markov model was used to simulate a cohort of 3 500 patients with compensated HCV related cirrhosis who would either be screened biannually with US and AFP or be followed expectantly. Therapeutic alternatives included surgical resection and percutaneous ethanol injection (PEI). The probabilities of clinical events were extracted from a systematic review of the literature on HCC and hepatitis C in Western patients; costs were determined from a third party payer perspective, in 1997 Canadian dollars; utilities were generated from a computerized interview of members of the general public; costs and utilities were discounted at 3% per year. Results. Screening is associated with an incremental cost-effectiveness ratio of 6 820 dollars per quality-adjusted life year ($/QALY). Screening was an economically attractive strategy over the entire range of possible values of all variables. Conclusion. Screening for HCC with liver US and AFP in hepatitis C-related cirrhosis is a highly cost-effective strategy, even in populations with a low incidence of HCC.

Study aim and objectives. The aim of this analysis is to identify and describe the relationship of factors associated with pressure ulcers, Stage 2 or greater, in adults in acute care hospitals. The objectives are: (1) to develop a model to describe the association of demographic and clinical factors in the presence of pressure ulcers using three years of prevalence data (1993, 1994 & 1995); and (2) sample, namely the 1996 prevalence study. Design. Cross-sectional, prevalence studies. Subjects. All adult inpatients in an acute care, university teaching hospital during one 12 hour day time period. Data were collected mid-week to reflect new admissions, and pre and post-operative cases, and in mid-September to avoid summer and winter seasonal variations. Main outcome measure. Stage 2 or greater pressure ulcers according to the Agency for Health Care Policy and Research Clinical Practice Guidelines, Pressure Ulcers in Adults: Prediction and Prevention (1992) recommendations for staging ulcers. Data collection instruments. Demographic and Clinical Profile Form, Prevalence Grid, and Braden Scale (1987). Sample size. The derivation sample, 1993--95 prevalence studies, included 1,992 subjects and the validation sample, 1996 prevalence study, included 581 subjects. (Abstract shortened by UMI.)

Background. Traditional hypertension guidelines from different countries or organizations often specified different treatment thresholds. These discrepancies have enormous public health implication. As the choice of treatment threshold is a utility-sensitive decision, determination of the preferences of practicing physicians and hypertensive patients is important for future policy making. Methods. A survey to determine the minimal clinically important differences (MCIDs) of patients and physicians for the initiation of antihypertensive therapy in the primary prevention of cardiovascular disease. Physicians were randomly selected from the population of all family physicians in the Ottawa-Carleton region and hypertensive patients without symptomatic cardiovascular disease were recruited from a convenience sample of five family physicians and four general internists. Both groups were presented with six hypothetical scenarios which described the same blood pressure (150/95 mm Hg) but different baseline cardiovascular risks (2%, 5%, and 10% in five years, and 15%, 30%, and 50% in twenty years). For each scenario, subjects were asked whether they would prescribe/accept treatment and, if they would, a probability trade-off technique was used to determine their MCID for antihypertensive therapy. (Abstract shortened by UMI.)

Problem statement. This study examines the parent decision to consult a physician, a physician diagnostic decision and a treatment decision in a common childhood illness, acute otitis media (AOM). Method. Physicians and parents of children with suspected ear infection consulting an emergency department in March--June 1998 were surveyed to describe factors related to parent and physician diagnostic and treatment decisions. Results. Parents consulted the ED when their usual caregiver was unavailable. Thirty-eight percent of 769 children were diagnosed with AOM. Presence of earache, absence of fever, parent suspicion of ear infection, and physician work status were each significantly associated with AOM diagnosis. Antibiotics were prescribed for 78% of AOM children. Presence of earache, fever and physician work status was each significantly associated with a decision to prescribe antibiotics. Conclusion. This study provides information to support the development of a physician-parent guide to the diagnosis and treatment of AOM.

Statement of the problem. Pulmonary Embolism (PE) is a common, lethal and treatable condition that is only present in a minority of those investigated with suspected PE. A clinical prediction rule that safely excludes PE could avert the need for many expensive diagnostic tests and improve patient management. Methods. Phase I - Using univariate techniques potential predictor variables were identified from a prospective cohort study of patients with suspected PE who subsequently had outcomes measured (Derivation set). Phase II - The inter-observer reliability of these individual predictor variables were determined in a second prospective cohort study of patients with suspected PE (Inter-observer reliability study). Phase III - Two multivariate techniques (recursive partitioning and logistic regression) were used to derive clinical prediction rules in the derivation set based on those variables that were both significant in univariate analysis (p < 0.20) (Phase I) and had good inter-observer reliability (kappa > 0.5) (Phase II). The clinical prediction rule with the highest specificity with close to 100% sensitivity was then identified using classification analysis in the derivation set. Phase IV - The rule was then retrospectively validated in a third dataset from a previously published prospective cohort study of patients with suspected PE (Validation set). (Abstract shortened by UMI.)

Deep venous thrombosis (DVT) of the lower extremity is a serious illness with an estimated incidence of 1 per 1000 persons per year. Objectives. To compare the lifetime risks and benefits of three months, six months, twelve months, two years, and lifelong anticoagulation for first episode idiopathic DVT. Secondary objectives were to assess quality of life for patients on warfarin therapy for DVT and for patients with post-thrombosic syndrome. A third objective was to determine if quality of life for these two health states differed between patients and healthy volunteers. Methods. Decision analysis with a Markov model was used to simulate patients with first episode idiopathic DVT who would be treated with durations of therapy ranging from three months to lifelong. The probabilities of clinical events were extracted from a systematic review of the literature on duration of therapy for DVT as well as rates of bleeding secondary to anticoagulant therapy and rates of developing post-thrombotic syndrome. Utilities for each of the associated health outcomes were elicited from patients and healthy volunteers using a computerized interview. (Abstract shortened by UMI.)