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Biomedical subjects

Andreas Laupacis

Publications and source records attributed to Andreas Laupacis.

At least 19 recordsLinked to original sources
PubMed2006

Changes in rates of upper gastrointestinal hemorrhage after the introduction of cyclooxygenase-2 inhibitors in British Columbia and Ontario.

BACKGROUND: Population rates of upper gastrointestinal (GI) hemorrhage have been observed to increase with the introduction and rapid uptake of selective cyclooxygenase-2 (COX-2) inhibitors. Changes in COX-2 inhibitor use and upper GI bleeding rates in regions with relatively restrictive drug policies (e.g., British Columbia) have not been compared with changes in regions with relatively less restrictive drug policies (e.g., Ontario). METHODS: We collected administrative data for about 1.4 million people aged 66 years and older in British Columbia and Ontario for the period January 1996 to November 2002. We examined temporal changes in the prevalence of NSAID use and admissions to hospital because of upper GI hemorrhage in both provinces using cross-sectional time series analysis. RESULTS: During the period studied, the prevalence of NSAID use in British Columbia's population of older people increased by 25% (from 8.7% to 10.9%; p < 0.01), as compared with a 51% increase in Ontario (from 10.9% to 16.5%; p < 0.01). Hospital admissions because of upper GI hemorrhage increased significantly in Ontario by about 16% on average, or about 2 admissions per 10 000 elderly people, above expected values (p < 0.01). A similar increase was not observed in British Columbia. INTERPRETATION: More restrictive drug coverage policies, although limiting access to drugs and their potential benefits, may protect the population from adverse drug effects.

Aged↗
PubMed2006

Variant Creutzfeldt-Jakob disease and the Canadian blood system after the tainted blood tragedy.

The transfusion transmission of hepatitis C and HIV to thousands of Canadian blood recipients was one of this country's largest public health catastrophes. In response to this crisis, and in an effort to prevent such a tragedy from occurring again, the Canadian blood system has undergone substantial reform. Variant Creutzfeldt-Jakob (vCJD) disease was the first infectious threat faced by the blood system since undergoing reform. The response at the time to this risk provides insights into the Canadian blood system's new approach to infectious threats. Our analysis of the decision-making concerning vCJD identifies two dominant themes characterizing the new blood system's approach to safety: (1) the adoption of a precautionary approach to new risks which involves taking action in advance of definitive evidence, and (2) risk aversion amongst policy makers, which has contributed to the adoption of safety measures with comparatively high cost-effectiveness ratios. Overall the principles governing the new blood system have contributed to the system both providing protection against emerging infectious risks and regaining the confidence of the public and recipients. However, the current set of policy factors will likely contribute to increasingly risk-averse policy making that will contribute to continued increases in the cost of the blood system. The challenge the blood system now faces is to find the appropriate balance between maximizing safety and ensuring the system remains affordable.

Blood Banks↗
PubMed2006

Case selection for statins was similar in two Canadian provinces: BC and Ontario.

OBJECTIVES: Though statins are fully reimbursed by the public drug programs for seniors in British Columbia (BC) and Ontario, Canada, population-based rates of statin prescription are markedly higher in Ontario. We aimed to assess whether new statin users in BC and Ontario differ in terms of their risk for future coronary heart disease (CHD) events. STUDY DESIGN AND SETTING: We collected information for 1998-2001 on demographics, outpatient prescriptions, physician visits, hospital admissions, and vital status from administrative databases to compare the proportions of new statin users aged 66 years and older who had evidence of an acute coronary syndrome (ACS), chronic CHD, neither ACS nor CHD but diabetes, or none of the above. RESULTS: Approximately 15% and 20% of BC and Ontario seniors, respectively, had filled a statin prescription by 2001. Among new statin users in the two provinces, virtually identical proportions had evidence of ACS (8%), chronic CHD (25%), and diabetes (14%), for an overall proportion of roughly 50% at high risk for CHD events. CONCLUSION: New statin users in BC and Ontario were at similar risk for future CHD events. Poorer case selection is unlikely to explain the relatively higher rates of statin prescription in Ontario.

Aged↗
PubMed2006

Effectiveness and efficiency of different guidelines on statin treatment for preventing deaths from coronary heart disease: modelling study.

OBJECTIVE: To examine the potential effectiveness and efficiency of different guidelines for statin treatment to reduce deaths from coronary heart disease in the Canadian population. DESIGN: Modelled outcomes of screening and treatment recommendations of six national or international guidelines--from Canada, Australia, New Zealand, the United States, joint British societies, and European societies. SETTING: Canada. DATA SOURCES: Details for 6760 men and women aged 20-74 years from the Canadian Heart Health Survey (weighted sample of 12,300,000 people) that included physical measurements including a lipid profile. MAIN OUTCOME MEASURES: The number of people recommended for treatment with statins, the potential number of deaths from coronary heart disease avoided, and the number needed to treat to avoid one coronary heart disease death with five years of statin treatment if the recommendations from each guideline were fully implemented. RESULTS: When applied to the Canadian population, the Australian and British guidelines were the most effective, potentially avoiding the most deaths over five years (> 15,000 deaths). The New Zealand guideline was the most efficient, potentially avoiding almost as many deaths (14,700) while recommending treatment to the fewest number of people (12.9% of people v 17.3% with the Australian and British guidelines). If their "optional" recommendations are included, the US guidelines recommended treating about twice as many people as the New Zealand guidelines (24.5% of the population, an additional 1.4 million people) with almost no increase in the number of deaths avoided. CONCLUSIONS: By focusing recommendations on people with the highest risk of coronary heart disease, the Canadian, US, and European societies guidelines could improve either their effectiveness (in terms of hundreds of avoided deaths) or efficiency (in terms of thousands of fewer people recommended treatment) in the Canadian population.

Adult↗
PubMed2006

Occurrence and impact of unanticipated variation in intravenous methotrexate dosing.

BACKGROUND: Studies using direct measurement suggest that the doses of up to 65% of drug infusions are outside industry standards. These preparation-associated errors occur despite routine safety procedures. As of April 5, 2006, the clinical impact of these errors had not been evaluated. OBJECTIVE: To measure the occurrence and associated clinical outcomes of variations in intravenous methotrexate dosing. METHODS: A prospective observational study was performed on 47 methotrexate infusions of 800 mg/m2 that were administered to 19 children with acute lymphoblastic leukemia. Serum methotrexate concentrations were measured at the end of the infusions, which were administered over 24 hours. The total methotrexate dose was determined by direct measurement of the concentration and the volume of each infusion. RESULTS: Dosing errors greater than or equal to 10% occurred in 11 (23%) infusions and ranged from -61% to 55% of the ideal dose. Repeated measures regression analysis found the measured total methotrexate dose was not significantly associated with the serum methotrexate concentration (p = 0.58) or with clinical toxicities. The methotrexate dose administered over the last hours of infusion (p = 0.006) and the serum creatinine level at diagnosis (p = 0.05) were the most significant predictors of the methotrexate concentration. High methotrexate concentrations were significantly associated with increased hepatic aminotransferase levels; however, the degree of elevation was of limited clinical relevance. CONCLUSIONS: While unexpected errors in drug dosing are more common than is suggested by other methods, the clinical impact observed in this model of methotrexate infusion was not demonstrably greater than medication errors described by other methods. Subsequent studies in this model of dosing error will require larger sample sizes, and other drugs should be evaluated.

Antimetabolites, Antineoplastic↗
PubMed2006

Impact of adverse events on prescribing warfarin in patients with atrial fibrillation: matched pair analysis.

OBJECTIVES: To quantify the influence of physicians' experiences of adverse events in patients with atrial fibrillation who were taking warfarin. DESIGN: Population based, matched pair before and after analysis. SETTING: Database study in Ontario, Canada. PARTICIPANTS: The physicians of patients with atrial fibrillation admitted to hospital for adverse events (major haemorrhage while taking warfarin and thromboembolic strokes while not taking warfarin). Pairs of other patients with atrial fibrillation treated by the same physicians were selected. MAIN OUTCOME MEASURES: Odds of receiving warfarin by matched pairs of a given physician's patients (one treated after and one treated before the event) were compared, with adjustment for stroke and bleeding risk factors that might also influence warfarin use. The odds of prescriptions for angiotensin converting enzyme (ACE) inhibitor before and after the event was assessed as a neutral control. RESULTS: For the 530 physicians who had a patient with an adverse bleeding event (exposure) and who treated other patients with atrial fibrillation during the 90 days before and the 90 days after the exposure, the odds of prescribing warfarin was 21% lower for patients after the exposure (adjusted odds ratio 0.79, 95% confidence interval 0.62 to 1.00). Greater reductions in warfarin prescribing were found in analyses with patients for whom more time had elapsed between the physician's exposure and the patient's treatment. There were no significant changes in warfarin prescribing after a physician had a patient who had a stroke while not on warfarin or in the prescribing of ACE inhibitors by physicians who had patients with either bleeding events or strokes. CONCLUSIONS: A physician's experience with bleeding events associated with warfarin can influence prescribing warfarin. Adverse events that are possibly associated with underuse of warfarin may not affect subsequent prescribing.

Adult↗
PubMed2006

Warfarin prescribing in atrial fibrillation: the impact of physician, patient, and hospital characteristics.

PURPOSE: The study investigated the determinants of warfarin use in patients with atrial fibrillation (AF). METHODS: We assembled a retrospective cohort of community-dwelling elderly patients (aged > or = 66 years) with AF using linked administrative databases. We identified the physicians responsible for the ambulatory care of these patients using physician service claims and compared patients who did and did not have an identifiable provider. For those patients with an identifiable provider, we assessed the association between patient, physician, and hospital factors and warfarin use. RESULTS: Our cohort consisted of 140,185 patients, of whom 116,200 (83%) had an identifiable cardiac provider. Patients without a provider were significantly more likely to have comorbid conditions that increase their risk of warfarin-associated bleeding. After adjustment for clinical factors, patients without a provider were significantly less likely to receive warfarin (odds ratio 0.37, 95% confidence interval: 0.36-0.38). Of patients with providers, 50,551 patients (43.5%) received warfarin within 180 days after hospital discharge. Warfarin use was positively associated with AF-associated stroke risk factors (eg, prior stroke, congestive heart failure) and negatively associated with warfarin-associated bleeding risk factors (eg, history of intracerebral hemorrhage). After controlling for patient and hospital factors, patients cared for by noncardiologist physicians with cardiology consultation were more likely to receive warfarin then patients treated in noncollaborative environments. CONCLUSIONS: Warfarin continues to be substantially underprescribed to patients who are at high risk for AF-associated cardioembolic stroke. Our findings highlight the need for targeted quality improvement interventions and suggest preferred models of AF care involving routine collaboration between cardiologists and other physicians.

Aged↗
PubMed2006

Hospital volume and mortality for mechanical ventilation of medical and surgical patients: a population-based analysis using administrative data.

OBJECTIVE: In an effort to improve efficiency and quality of care, regionalization of adult critical care services, similar to trauma and neonatal intensive care, has been suggested. However, there is little research to understand if hospitals with higher patient volumes have better outcomes. Our objective is to determine whether hospital volume is associated with improved survival for medical or surgical patients receiving mechanical ventilation. DESIGN: Population-based retrospective cohort study. SETTING: Province of Ontario, Canada. PATIENTS: A total of 13,846 medical and 6,373 surgical patients receiving mechanical ventilation for greater than two consecutive days between 1998 and 2000. INTERVENTIONS: None. MEASUREMENTS: Odds ratio for death within 30 days of initiation of mechanical ventilation was calculated in relation to hospital volume of ventilation. Estimates were adjusted for patient demographics, diagnoses, and urgency status; hospital region and rural location; and accounted for clustering within hospitals. MAIN RESULTS: There was no effect of volume on mortality for surgical patients. After adjustment for clustering, among medical patients, the lowest-volume category (<100 episodes/yr) had a nonsignificant increase in mortality, with an odds ratio (95% confidence interval) of 1.13 (0.87-1.47) compared with the highest-volume category (> or =700 episodes/yr). A post hoc analysis revealed that within the lowest-volume category, the proportion of patients transferred to larger hospitals was 81% for hospitals with <20 episodes/yr and only 32% for hospitals with 20-99 episodes/yr, with odds ratios (95% confidence interval) for mortality of 0.74 (0.49-1.12) and 1.18 (0.90-1.54), respectively, compared with the highest-volume category. CONCLUSIONS: For surgical patients requiring mechanical ventilation for >2 days, hospital volume had no effect on mortality. For medical patients, higher mortality may occur in a subgroup of low-volume hospitals that do not routinely transfer their patients to larger-volume facilities. This finding needs further investigation in a larger-sized study.

Aged↗
PubMed2006

Economic evaluations in the canadian common drug review.

The Canadian Common Drug Review (CDR) was established in 2003 to provide a single process for making formulary recommendations to most Canadian publicly funded drug plans. This paper considers the most common challenges faced by the CDR: (a) determining the effectiveness of a drug (particularly interpreting the importance of surrogate markers and changes in QOL measures); (b) the massive rise in the cost of new drugs, which, in general, does not seem to accompanied by a massive increase in effectiveness; (c) interpreting complex pharmacoeconomic evaluations which often do not provide straightforward answers about the cost effectiveness of a drug; (d) prescription creep (the tendency for drugs in the real world to be used in patients who were not studied in clinical trials, thus raising concerns about a drug's real-world cost effectiveness; and (e) ethical and societal issues, particularly the reimbursement of expensive drugs for rare diseases.

Canada↗
PubMed2005

Risk-treatment mismatch in the pharmacotherapy of heart failure.

CONTEXT: Patients with heart failure have a wide spectrum of mortality risks. To maximize the benefit of available pharmacotherapies, patients with high mortality risk should receive high rates of drug therapy. OBJECTIVE: To examine patterns of drug therapy and underlying mortality risk in patients with heart failure. DESIGN, SETTING, AND PATIENTS: In the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) population-based cohort (1999-2001) of 9942 patients with heart failure hospitalized in Ontario, Canada, we evaluated 1418 patients with documented left ventricular ejection fraction of 40% or less and aged 79 years or younger with low-, average-, and high-predicted risk of death within 1 year; all patients survived to hospital discharge. Administration of angiotensin-converting enzyme (ACE) inhibitors, ACE inhibitors or angiotensin II receptor blockers (ARBs), and beta-adrenoreceptor antagonists was evaluated according to predicted risk of death. MAIN OUTCOME MEASURE: Heart failure drug administration rates at time of discharge and 90 days after hospital discharge. RESULTS: At hospital discharge, prescription rates for patients in the low-, average-, and high-risk groups were 81%, 73%, 60%, respectively, for ACE inhibitors; 86%, 80%, 65%, respectively, for ACE inhibitors or ARBs; and 40%, 33%, 24%, respectively, for beta-adrenoreceptor antagonists (all P<.001 for trend). Within 90 days following hospital discharge, the rates were 83%, 76%, and 61% for ACE inhibitors; 89%, 83%, and 67% for ACE inhibitors or ARBs; and 43%, 36%, and 28% for beta-adrenoreceptor antagonists for the 3 risk groups, respectively (all P<.001 for trend). The pattern of lower rates of drug administration in those patients at increasing risk was maintained up to 1 year postdischarge (P<.001). After accounting for varying survival time and potential contraindications to therapy, low-risk patients were more likely to receive ACE inhibitors or ARBs (adjusted hazard ratio [HR], 1.61; 95% confidence interval [CI], 1.49-1.74) and beta-adrenoreceptor antagonists (HR, 1.80; 95% CI, 1.60-2.01) compared with high-risk patients (both P<.001). CONCLUSIONS: Patients with heart failure at greatest risk of death are least likely to receive ACE inhibitors, ACE inhibitors or ARBs, and beta-adrenoreceptor antagonists. Understanding the reasons underlying this mismatch may facilitate improvements in care and outcomes for patients with heart failure.

Adrenergic beta-Antagonists↗
PubMed2005

Propensity score methods gave similar results to traditional regression modeling in observational studies: a systematic review.

OBJECTIVE: To determine whether adjusting for confounder bias in observational studies using propensity scores gives different results than using traditional regression modeling. METHODS: Medline and Embase were used to identify studies that described at least one association between an exposure and an outcome using both traditional regression and propensity score methods to control for confounding. From 43 studies, 78 exposure-outcome associations were found. Measures of the quality of propensity score implementation were determined. The statistical significance of each association using both analytical methods was compared. The odds or hazard ratios derived using both methods were compared quantitatively. RESULTS: Statistical significance differed between regression and propensity score methods for only 8 of the associations (10%), kappa = 0.79 (95% CI = 0.65-0.92). In all cases, the regression method gave a statistically significant association not observed with the propensity score method. The odds or hazard ratio derived using propensity scores was, on average, 6.4% closer to unity than that derived using traditional regression. CONCLUSIONS: Observational studies had similar results whether using traditional regression or propensity scores to adjust for confounding. Propensity scores gave slightly weaker associations; however, many of the reviewed studies did not implement propensity scores well.

Bias↗