Expression of human tissue factor under the control of the mouse tissue factor promoter mediates normal hemostasis in knock-in mice

BACKGROUND

Tissue factor (TF) is expressed widely at the subluminal surface of blood vessels and serves as the primary cellular initiator of the extrinsic pathway of blood coagulation. Lack of TF in mice resulted in lethality in utero, but human TF (huTF) expressed at low levels from a human minigene rescued null mice from prenatal death. Although these low-TF expressing transgenic mice developed to term, they had a significantly shorter life span and exhibited hemorrhage and fibrosis in the heart.

METHODS

Human TF knock-in (TFKI) mice were generated by replacing the first two exons of the mouse (murine) TF (muTF) gene with the huTF complete coding sequence, thus placing it under the control of the endogenous muTF promoter.

RESULTS

Expression of huTF in the TFKI mice was similar to muTF in wild-type (wt) mice. The TFKI mice showed no microscopic evidence of spontaneous hemorrhage in the heart, nor cardiac fibrosis at up to 18 months of age. Immunohistochemistry showed that huTF was expressed in cells surrounding blood vessels in TFKI mice. Coagulation activity of brain homogenates from TFKI mice was comparable with that from wt brain. Cardiac hemorrhage similar to that of the low-TF transgenic mice occurred in the TFKI mice when huTF was blocked by a neutralizing anti-huTF monoclonal antibody.

CONCLUSION

We generated a transgenic mouse line that expresses huTF under the control of the endogenous muTF promoter at physiological levels. Our results suggest that huTF can fully reconstitute the murine coagulation system and mediate normal hemostasis.

Expression of human tissue factor under the control of the mouse tissue factor promoter mediates normal hemostasis in knock-in mice

BACKGROUND

Tissue factor (TF) is expressed widely at the subluminal surface of blood vessels and serves as the primary cellular initiator of the extrinsic pathway of blood coagulation. Lack of TF in mice resulted in lethality in utero, but human TF (huTF) expressed at low levels from a human minigene rescued null mice from prenatal death. Although these low-TF expressing transgenic mice developed to term, they had a significantly shorter life span and exhibited hemorrhage and fibrosis in the heart.

METHODS

Human TF knock-in (TFKI) mice were generated by replacing the first two exons of the mouse (murine) TF (muTF) gene with the huTF complete coding sequence, thus placing it under the control of the endogenous muTF promoter.

RESULTS

Expression of huTF in the TFKI mice was similar to muTF in wild-type (wt) mice. The TFKI mice showed no microscopic evidence of spontaneous hemorrhage in the heart, nor cardiac fibrosis at up to 18 months of age. Immunohistochemistry showed that huTF was expressed in cells surrounding blood vessels in TFKI mice. Coagulation activity of brain homogenates from TFKI mice was comparable with that from wt brain. Cardiac hemorrhage similar to that of the low-TF transgenic mice occurred in the TFKI mice when huTF was blocked by a neutralizing anti-huTF monoclonal antibody.

CONCLUSION

We generated a transgenic mouse line that expresses huTF under the control of the endogenous muTF promoter at physiological levels. Our results suggest that huTF can fully reconstitute the murine coagulation system and mediate normal hemostasis.

Expression of ovarian steroid hormone receptors in tuberoinfundibular dopaminergic neurones during pregnancy and lactation

During late-pregnancy, tuberoinfundibular dopaminergic (TIDA) neurones, a critical component of the negative-feedback loop regulating prolactin secretion, become unresponsive to the stimulatory effects of prolactin. The change in TIDA responsiveness to prolactin at this time results in a decrease in dopamine secretion and a prolactin surge. As the onset of parturition and the antepartum prolactin surge depend on the withdrawal of progesterone in the presence of oestrogen, it is likely that ovarian steroid hormones mediate this change in TIDA responsiveness. To determine whether ovarian steroids can directly modulate TIDA activity, and whether changes of receptor numbers might contribute to overall steroid-regulation of these neurones, we investigated the level of oestrogen receptor alpha (ERalpha) and progesterone receptor (PR) expression within TIDA neurones during pregnancy and lactation. Animals were sacrificed on dioestrous, days 12, 19 and 21 of pregnancy and day 5 of lactation, and the proportion of TIDA neurones expressing ERalpha or PR, as well as the total number of PR expressing cells within the arcuate nucleus, was determined. Approximately 75% and 55% of tyrosine hydroxylase neurones expressed ERalpha and PR, respectively. Levels of steroid receptor expression within TIDA neurones remained fairly constant, except for an increase in ERalpha on days 12 and 19 of pregnancy compared to dioestrous and lactation day 5. The presence of steroid receptors on TIDA neurones during pregnancy and lactation supports the concept of a direct effect of steroid hormones on these neurones at this time. Thus, steroid hormones may directly act on TIDA neurones to regulate maternal prolactin secretion. The relatively stable level of expression during late pregnancy suggests that a shift in steroid receptor expression during late pregnancy does not contribute to the change in TIDA responsiveness to prolactin at this time.

A Population-Based Study of Cholinesterase Inhibitor Use for Dementia

OBJECTIVES

To examine current utilization patterns of cholinesterase inhibitor (ChEI) therapy for dementia to determine treatment duration, use in long-term care, how often patients receive these drugs until death, and frequency of switching between the available ChEIs.

DESIGN

A population-based healthcare administrative database study.

SETTING

Patients aged 66 and older from the Canadian province of Ontario who received a new prescription for a ChEI between June 1, 2000, and December 31, 2002. Patients were followed until discontinuation of ChEI therapy, death, or end of the observation period (March 31, 2005).

PARTICIPANTS

Twenty-eight thousand nine hundred and sixty-one patients, including 4,601 residing in long-term care, mean age 80, 63% female.

MEASUREMENTS

Information on diagnosis, medical comorbidity, physician visits, and concomitant medication use was obtained. Estimates of duration of continuous use were determined. The percentage of patients who remained on the initial dose prescribed, the proportion who switched to a second ChEI, and the percentage who remained on ChEIs until death were calculated.

RESULTS

Patients had on average more than 26 physician visits in the year before ChEI therapy, but only 28% had seen a dementia specialist. Concomitant use of potentially inappropriate medications (strongly anticholinergic medications and benzodiazepines) was noted in 37% of patients. The average length of treatment for all patients was 866 days. Many patients (43%) remained on the initial dose prescribed, 6% switched to another ChEI, and 19% died while on ChEI therapy.

CONCLUSION

Elderly patients with dementia are treated for lengthy periods of time with ChEIs in the community and in long-term care facilities. Further research is required to determine whether these utilization patterns are appropriate. It is also unclear whether these results are generalizable to other populations without universal health coverage or drug formulary benefits.

Antipsychotic drug use and mortality in older adults with dementia

BACKGROUND

Antipsychotic drugs are widely used to manage behavioral and psychological symptoms in dementia despite concerns about their safety.

OBJECTIVE

To examine the association between treatment with antipsychotics (both conventional and atypical) and all-cause mortality.

DESIGN

Population-based, retrospective cohort study.

SETTING

Ontario, Canada.

PATIENTS

Older adults with dementia who were followed between 1 April 1997 and 31 March 2003.

MEASUREMENTS

The risk for death was determined at 30, 60, 120, and 180 days after the initial dispensing of antipsychotic medication. Two pairwise comparisons were made: atypical versus no antipsychotic use and conventional versus atypical antipsychotic use. Groups were stratified by place of residence (community or long-term care). Propensity score matching was used to adjust for differences in baseline health status.

RESULTS

A total of 27,259 matched pairs were identified. New use of atypical antipsychotics was associated with a statistically significant increase in the risk for death at 30 days compared with nonuse in both the community-dwelling cohort (adjusted hazard ratio, 1.31 [95% CI, 1.02 to 1.70]; absolute risk difference, 0.2 percentage point) and the long-term care cohort (adjusted hazard ratio, 1.55 [CI, 1.15 to 2.07]; absolute risk difference, 1.2 percentage points). Excess risk seemed to persist to 180 days, but unequal rates of censoring over time may have affected these results. Relative to atypical antipsychotic use, conventional antipsychotic use was associated with a higher risk for death at all time points. Sensitivity analysis revealed that unmeasured confounders that increase the risk for death could diminish or eliminate the observed associations.

LIMITATIONS

Information on causes of death was not available. Many patients did not continue their initial treatments after 1 month of therapy. Unmeasured confounders could affect associations.

CONCLUSIONS

Atypical antipsychotic use is associated with an increased risk for death compared with nonuse among older adults with dementia. The risk for death may be greater with conventional antipsychotics than with atypical antipsychotics.

Temperament and response to the Trier Social Stress Test

OBJECTIVE

The personality characteristics behavioural inhibition and neuroticism have been associated with mood and anxiety disorders and, in some studies, hypothalamic-pituitary-adrenal (HPA) axis hyperactivity. We recently reported that low levels of Novelty Seeking were associated with elevated plasma cortisol responses to the dexamethasone/corticotropin-releasing hormone (Dex/CRH) test in healthy adults with no psychiatric disorder. The present study tested the association between temperament and HPA axis function in the same group of subjects using a standardized psychosocial neuroendocrine stress test.

METHOD

Subjects completed diagnostic interviews, questionnaires, and the Trier Social Stress Test (TSST).

RESULTS

Novelty Seeking was inversely associated with plasma cortisol concentrations at baseline and throughout the TSST, but was not related to adrenocorticotropic hormone (ACTH) levels.

CONCLUSION

Results of this study extend our previous finding in the Dex/CRH test to a psychosocial stress test. Future investigations are needed to replicate these findings and further elucidate how temperament and personality are linked to HPA function.

Variation in Nursing Home Antipsychotic Prescribing Rates

BACKGROUND

Excessive prescribing of antipsychotic therapy is a concern owing to their potential to cause serious adverse events. We explored variation in the use of antipsychotic therapy across nursing homes in Ontario, Canada, and determined if prescribing decisions were based on clinical indications.

METHODS

A point-prevalence study of antipsychotic therapy use in 47 322 residents of 485 provincially regulated nursing homes in December 2003. Facilities were classified into quintiles according to their mean antipsychotic prescribing rates. Residents were grouped into those with a potential clinical indication or no identified clinical indication for antipsychotic therapy.

RESULTS

A total of 15 317 residents (32.4%) were dispensed an antipsychotic agent. The mean rate of antipsychotic prescribing by home ranged from 20.9% in the quintile of facilities with the lowest mean prescribing rates (quintile 1) to 44.3% in facilities with the highest mean prescribing rates (quintile 5). Compared with individuals residing in nursing homes with the lowest mean antipsychotic prescribing rates, those residing in facilities with the highest rates were 3 times more likely to be dispensed an antipsychotic agent (adjusted odds ratio [AOR], 3.0; 95% confidence interval [CI], 2.74-3.19). Similar rates were observed among residents with psychoses with or without dementia (AOR, 2.7; 95% CI, 2.35-3.09) and residents without psychoses or dementia (AOR, 2.9; 95% CI, 2.19-3.81) who had no identifiable indication for an antipsychotic therapy.

CONCLUSION

Residents in facilities with high antipsychotic prescribing rates were about 3 times more likely than those in facilities with low prescribing rates to be dispensed an antipsychotic agent, irrespective of their clinical indication.

A comparison of the ability of different propensity score models to balance measured variables between treated and untreated subjects: a Monte Carlo study

The propensity score--the probability of exposure to a specific treatment conditional on observed variables--is increasingly being used in observational studies. Creating strata in which subjects are matched on the propensity score allows one to balance measured variables between treated and untreated subjects. There is an ongoing controversy in the literature as to which variables to include in the propensity score model. Some advocate including those variables that predict treatment assignment, while others suggest including all variables potentially related to the outcome, and still others advocate including only variables that are associated with both treatment and outcome. We provide a case study of the association between drug exposure and mortality to show that including a variable that is related to treatment, but not outcome, does not improve balance and reduces the number of matched pairs available for analysis. In order to investigate this issue more comprehensively, we conducted a series of Monte Carlo simulations of the performance of propensity score models that contained variables related to treatment allocation, or variables that were confounders for the treatment-outcome pair, or variables related to outcome or all variables related to either outcome or treatment or neither. We compared the use of these different propensity scores models in matching and stratification in terms of the extent to which they balanced variables. We demonstrated that all propensity scores models balanced measured confounders between treated and untreated subjects in a propensity-score matched sample. However, including only the true confounders or the variables predictive of the outcome in the propensity score model resulted in a substantially larger number of matched pairs than did using the treatment-allocation model. Stratifying on the quintiles of any propensity score model resulted in residual imbalance between treated and untreated subjects in the upper and lower quintiles. Greater balance between treated and untreated subjects was obtained after matching on the propensity score than after stratifying on the quintiles of the propensity score. When a confounding variable was omitted from any of the propensity score models, then matching or stratifying on the propensity score resulted in residual imbalance in prognostically important variables between treated and untreated subjects. We considered four propensity score models for estimating treatment effects: the model that included only true confounders; the model that included all variables associated with the outcome; the model that included all measured variables; and the model that included all variables associated with treatment selection. Reduction in bias when estimating a null treatment effect was equivalent for all four propensity score models when propensity score matching was used. Reduction in bias was marginally greater for the first two propensity score models than for the last two propensity score models when stratification on the quintiles of the propensity score model was employed. Furthermore, omitting a confounding variable from the propensity score model resulted in biased estimation of the treatment effect. Finally, the mean squared error for estimating a null treatment effect was lower when either of the first two propensity scores was used compared to when either of the last two propensity score models was used.

Readers should systematically assess methods used to identify, measure and analyze confounding in observational cohort studies

OBJECTIVE

To describe techniques used to address confounding in published observational studies.

STUDY DESIGN AND SETTING

A systematic literature review identified studies using administrative or registry data to investigate health effects of drug therapies. Studies published from January 2001 to December 2005 came from BMJ, New England Journal of Medicine, Lancet, Annals of Internal Medicine, and JAMA. A structured abstraction form was used to collect information about confounding.

RESULTS

The search identified 29 studies. Twenty-two studies (76%) had 10,000 or more subjects and 18 (62%) used a mortality outcome. None mentioned use of a literature search to identify confounders, however, 28 (97%) listed confounders included, and 26 (90%) listed confounders not included in the study. Eighteen (62.1%) discussed the validity of confounder data. Most (22, or 76%) studies included a table with the distribution of confounders but none used effect size to assess imbalance between comparison groups. Almost all studies used regression techniques (28, or 97%); fewer used stratification (16, or 55%) or matching (four, or 14%) to address confounding. Eleven (40%) studies discussed sensitivity analyses.

CONCLUSION

Published cohort studies routinely include a list of potential confounders but there is room for improvement in confounder identification, measurement, and analysis.

Using pharmacoepidemiology to inform drug coverage policy: initial lessons from a two-province collaborative

Prescription drug plan managers seek "real-world" evidence regarding the safety and effectiveness of drugs and drug coverage policies. University-based pharmacoepidemiologists with access to administrative health data can help meet these information needs and, by collaborating with other health plans, exploit variations in plan policy. Canada, with its universal health insurance, public drug benefit plans, and population-based linked health care databases, is an ideal setting for such research. Here we describe our initial experience in collaborating with researchers and drug plan managers in British Columbia and Ontario.

Differential effects of centrally-administered oestrogen antagonist ICI-182,780 on oestrogen-sensitive functions in the hypothalamus

Oestrogen actions within the hypothalamus are essential for a range of reproductive functions. In this study, we sought to develop a method for suppressing central oestrogen action without affecting peripheral oestrogenic effects. We administered the oestrogen receptor antagonist ICI-182,780 (ICI) via crystalline implants into the left lateral ventricle or the arcuate nucleus and measured the effectiveness of this drug on three endpoints known to be regulated by oestrogen: gonadotrophin-releasing hormone (GnRH) pulse frequency, progesterone receptor expression and the generation of a sustained prolactin surge during late pregnancy. To confirm that central ICI administration had no effect on peripheral actions of oestrogen, we monitored changes in uterine weight. Intracerebroventricular ICI treatment reversed the inhibitory effects of oestrogen on GnRH pulse frequency, as measured by plasma luteinising hormone pulse frequency. No effect on the oestrogenic induction of progesterone receptors within the arcuate nucleus or ventromedial hypothalamus was observed; however, a small yet significant reduction in progesterone receptor expression within dopaminergic neurones in the arcuate nucleus was observed. Intracerebroventricular or direct crystalline ICI administration to the arcuate nucleus did not change the serum prolactin level during late pregnancy. Central administration of ICI did not affect uterine weight, and thus did not have a peripheral effect. These data suggest that central administration of ICI can overcome some actions of oestrogen in the brain, such as GnRH pulse frequency, but does not affect other oestrogen mediated actions, including the induction of progesterone receptors or the antepartum prolactin surge. Thus, it appears that there is a differential sensitivity to the inhibition of central oestrogen actions by ICI.

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.

Conditioning on the propensity score can result in biased estimation of common measures of treatment effect: a Monte Carlo study

Propensity score methods are increasingly being used to estimate causal treatment effects in the medical literature. Conditioning on the propensity score results in unbiased estimation of the expected difference in observed responses to two treatments. The degree to which conditioning on the propensity score introduces bias into the estimation of the conditional odds ratio or conditional hazard ratio, which are frequently used as measures of treatment effect in observational studies, has not been extensively studied. We conducted Monte Carlo simulations to determine the degree to which propensity score matching, stratification on the quintiles of the propensity score, and covariate adjustment using the propensity score result in biased estimation of conditional odds ratios, hazard ratios, and rate ratios. We found that conditioning on the propensity score resulted in biased estimation of the true conditional odds ratio and the true conditional hazard ratio. In all scenarios examined, treatment effects were biased towards the null treatment effect. However, conditioning on the propensity score did not result in biased estimation of the true conditional rate ratio. In contrast, conventional regression methods allowed unbiased estimation of the true conditional treatment effect when all variables associated with the outcome were included in the regression model. The observed bias in propensity score methods is due to the fact that regression models allow one to estimate conditional treatment effects, whereas propensity score methods allow one to estimate marginal treatment effects. In several settings with non-linear treatment effects, marginal and conditional treatment effects do not coincide.

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.

Development of measures of the quality of emergency department care for children using a structured panel process

BACKGROUND

Performance measures are essential components of public reporting and quality improvement. To date, few such measures exist to provide a comprehensive assessment of the quality of emergency department services for children.

OBJECTIVES

Our goal was to use a systematic process to develop measures of emergency department care for children (0-19 years) that are (1) based on research evidence and expert opinion, (2) representative of a range of conditions treated in most emergency departments, (3) related to links between processes and outcomes, and (4) feasible to measure.

METHODS

We presented a panel of providers and managers data from emergency department use to identify common conditions across levels of patient acuity, which could be targets for quality improvement. We used a structured panel process informed by a literature review to (1) identify condition-specific links between processes of care and defined outcomes and (2) select indicators to assess these process-outcome links. We determined the feasibility of calculating these indicators using an administrative data set of emergency department visits for Ontario, Canada.

RESULTS

The panel identified 18 clinical conditions for indicator development and 61 condition-specific links between processes of care and outcomes. After 2 rounds of ratings, the panel defined 68 specific clinical indicators for the following conditions: adolescent mental health problems, ankle injury, asthma, bronchiolitis, croup, diabetes, fever, gastroenteritis, minor head injury, neonatal jaundice, seizures, and urinary tract infections. Visits for these conditions account for 23% of all pediatric emergency department use. Using an administrative data set, we were able to calculate 19 indicators, covering 9 conditions, representing 20% of all emergency department visits by children.

CONCLUSIONS

Using a structured panel process, data on emergency department use, and literature review, it was possible to define indicators of emergency department care for children. The feasibility of these indicators will depend on the availability of high-quality data.

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.

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.

Revisiting Rose: strategies for reducing coronary heart disease

The way we assess risk of coronary heart disease has become more accurate in recent years. How does this affect the efficacy of primary and secondary prevention strategies?

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.

The identification and development of Canadian coronary artery bypass graft surgery quality indicators

OBJECTIVE

The study objective was to develop quality indicators for coronary artery bypass graft surgery that relate to quality of care, associate with preventable death, and could be reported on performance reports.

METHODS

A comprehensive list of quality indicators was collected from quality improvement organizations including the Society For Thoracic Surgery, Northern New England Cardiovascular Disease Study Group, and Veteran's Affairs System. Indicators were collated from practice guidelines from the American College of Cardiology and the American Heart Association. A MEDLINE search using the keywords "quality indicators" and "coronary bypass" was completed. A 17-member multidisciplinary international expert panel was assembled, who voted using a 2-step Delphi process regarding association with quality of care, risk adjustment, association with preventable death, and inclusion on performance reports.

RESULTS

A total of 149 quality indicators were examined. This list was distilled to 33 indicators related to quality of care, 10 indicators that could be adequately risk adjusted, 34 indicators related to preventable death, and 18 indicators to be included on performance reports. These selected indicators consisted of 19 outcome variables, 23 process of care variables, and 4 structure variables. The quality indicators believed to be useful on a Canadian institutional coronary artery bypass graft surgery report card included the following: 30-day mortality, in-hospital mortality, electrocardiographic myocardial infarction, red cell transfusion, allogeneic blood product transfusion, deep sternal wound infection, postoperative stroke, postoperative dialysis, intensive care unit readmission, intensive care unit length of stay, ventilation time, repeat cardiac operation, repeat surgery with cardiopulmonary bypass, repeat revascularization, waiting time to surgery, completion of surgery within a recommended waiting time, use of left internal thoracic artery graft, and institutional volume.

CONCLUSIONS

This set of consensus quality indicators can be used as a standard list to be monitored by providers of coronary artery bypass graft surgery in an effort to continuously evaluate and improve their performance.

Atypical antipsychotics and parkinsonism

BACKGROUND

Atypical antipsychotic agents are thought to be less likely than older typical agents to produce parkinsonism. This has not been well documented. We compared the risk of development of incident parkinsonism among older adults dispensed atypical relative to typical antipsychotics.

METHODS

Retrospective cohort study of all adults 66 years and older in Ontario. We used Cox proportional hazards models to study the association between the type, potency, and dose of antipsychotic dispensed and the development of parkinsonism during 1 year of follow-up.

RESULTS

All 25,769 older adults prescribed antipsychotics were observed for 11,573 person-years, and 449 events of parkinsonism were identified. Relative to individuals dispensed an atypical antipsychotic, those dispensed a typical agent were 30% more likely (adjusted hazard ratio [HR], 1.30; 95% confidence interval [CI], 1.04-1.58) and those exposed to neither agent were 60% less likely (HR, 0.40; 95% CI, 0.29-0.43) to experience development of parkinsonism. Furthermore, those dispensed lower-potency typical agents were no different (HR, 0.75; 95% CI, 0.48-1.15), and those dispensed higher-potency typical antipsychotics were at close to a 50% greater risk (HR, 1.44; 95% CI, 1.13-1.84) of development of parkinsonism relative to atypical antipsychotics. Relative to those dispensed a high-dose atypical antipsychotic, those dispensed a typical antipsychotic were at similar risk for parkinsonism (Wald chi(2) = 0.14, P = .7).

CONCLUSIONS

The risk of development of parkinsonism associated with the use of high-dose atypical antipsychotics was similar to that associated with the use of typical antipsychotics. Caution should be used when prescribing atypical antipsychotic therapy at high doses.

Both clinical epidemiology and population health perspectives can define the role of health care in reducing health disparities

OBJECTIVE

To compare and contrast clinical epidemiology and population health perspectives on the role of health care in reducing socioeconomic disparities in health.

STUDY DESIGN AND SETTING

A review of concepts outlined in selected articles on population health and clinical epidemiology and a systematic literature search for randomized controlled trials (RCTs) of therapeutic interventions for cardiovascular disease that contained analysis of outcomes by socioeconomic status.

RESULTS

Population health has a focus on health disparities, particularly disparities related to socioeconomic status, and many of its proponents have a pessimistic view of the degree to which health care can reduce these disparities. Clinical epidemiology has a focus on the production of valid evidence on the impact of health care interventions; however, RCTs rarely report the impact of interventions across socioeconomic strata. Both population health and clinical epidemiology share the view that efficacy, effectiveness, and cost-effectiveness are all important in defining the impact of health care on health disparities.

CONCLUSION

Principles drawn from both population health and clinical epidemiology could be used to provide a clearer picture of the role that health care interventions can have on socioeconomic disparities in health and to identify implications for policy, research, and clinical practice.

Relationships between serotonin transporter promoter polymorphism, platelet serotonin transporter binding and clinical phenotype in suicidal and non-suicidal adolescent inpatients

Relationships between the serotonin transporter promoter polymorphism (5-HTTLPR), platelet serotonin transporter (SERT) binding and clinical phenotype were examined in 32 suicidal and 28 non-suicidal Ashkenazi Israeli adolescent psychiatric inpatients. The 5-HTTLPR polymorphism was not associated with transporter binding or with suicidality or other clinical phenotypes. However, in the suicidal group, a significant positive correlation between platelet SERT density and anger scores (n=32, r=.40; p=.027) and a negative correlation between platelet count and trait anxiety (n=32, r=-.42; p=.034) were observed.