A tale of two countries: Insights from the differences in Canadian/American patterns of care for patients with acute coronary syndromes

Do operator volumes relate to clinical outcomes after percutaneous coronary intervention in the Canadian health care system?

BACKGROUND

Many US studies have documented an association between operator volume and outcomes after percutaneous coronary intervention (PCI). No study has assessed whether this relationship exists in Canada, where PCI is performed only at a limited number of regional centers and operator volumes are higher.

METHODS

All PCI procedures performed in the province of Ontario from 1995 to 2001 were analyzed using administrative databases. The outcomes of interest were coronary artery bypass graft during the same hospitalization, mortality at 30 days, or the combined end point.

RESULTS

A total of 38,561 PCI procedures were performed by 65 physicians at 8 centers. Over the study period, risk-adjusted coronary artery bypass graft rates fell from 2.0% in 1995 to 0.7% in 2000 (P < .0001) with no change in mortality. The median annual PCI volume was 132 (25th, 75th percentile: 81, 182) cases. After stratifying operators by average annual PCI volume into low (< 155 cases), intermediate (155-195 cases), and high (> 195 cases) volume, there were no significant linear relationships between risk-adjusted outcomes and operator terciles. No significant correlations were seen between individual PCI volume and risk-adjusted rates of mortality, bypass surgery, or the combined end point (P = .2, P = .35, and P = .95, respectively).

CONCLUSIONS

In contrast to US studies, there does not appear to be an association between PCI volume and outcomes in Ontario. These findings may be related to the high annual volumes of most operators and institutions within Ontario.

Are international differences in the outcomes of acute coronary syndromes apparent or real? A multilevel analysis

STUDY OBJECTIVE

International variation in the outcomes of patients with acute coronary syndromes (ACS) has been well reported. The relative contributions of patient, hospital, and country level factors on clinical outcomes, however, remain unclear, and thus, was the objective of this study.

DESIGN

Multilevel logistic regression models were developed for death/(re)infarction (MI) at 30 days and death in one year, with patients (1st level) nested in hospitals (2nd level) and hospitals in countries (3rd level).

SETTINGS

The GUSTO IV ACS clinical trial was carried out at 458 hospital sites in 24 countries.

PATIENTS

7800 non-ST segment elevation (NSTE) ACS patients.

MAIN RESULTS

There were substantial variations among countries in the processes and outcomes of care at 30 days, ranging from 5.4% to 50.0% for percutaneous coronary intervention, 4.3% to 21.2% for coronary artery bypass graft surgery, 5.0% to 13.9% for 30 day death/(re)MI, and 4.9% to 14.8% for one year mortality. However, the residual inter-country variations in 30 day death/(re)MI and one year mortality became non-significant and nearly disappeared (p > 0.500 for both) after adjusting for key baseline patient characteristics and hospital factors, which became significant (p < 0.01 for both). Patient level factors accounted for 96%-99% of total variation in these end points, leaving the remaining 1% and 4% of variance attributable to hospital level factors.

CONCLUSION

The international differences in clinical outcomes in this study of NSTE ACS are primarily accounted for by the patient level factors, with hospital level factors playing a minor part, and the country level factors a negligible one. These findings have significant policy and research implications involving international collaboration and comparisons.

Synergy between publication and promotion: comparing adoption of new evidence in Canada and the United States

PURPOSE

Few studies have examined the effect of new evidence from clinical trials on physician practice. We took advantage of differences in promotional activity in Canada and the United States for the Heart Outcomes Prevention and Evaluation (HOPE) study and the Randomized Aldactone Evaluation Study (RALES) to determine if publication of new evidence changes practice, and the extent to which promotion influences adoption of new evidence.

METHODS

We used longitudinal dispensing data, collected from 1998 to 2001, to examine changes in prescribing patterns for ramipril and other angiotensin-converting enzyme (ACE) inhibitors before and after the HOPE study. We also obtained estimates for promotional expenditures. We stratified analyses by country, to isolate the effect of promotion, and used interrupted time series methods to adjust for pre-existing prescribing trends. Similar analyses were conducted for spironolactone use before and after RALES.

RESULTS

Publication of the HOPE study results was associated with rapid increases in the use of ramipril. After adjusting for pre-existing prescribing trends, ramipril prescribing increased by 12% per month (P = 0.001) in Canada versus 5% per month (P = 0.001) in the United States after the study results were presented and published. One year later, ramipril accounted for 30% of the ACE inhibitor market in Canada versus 6% in the United States. The year before publication of these results, expenditures for detailing increased by 20% in Canada (to 18 US dollars per physician) but decreased by 7% in the United States (to 13 US dollars per physician); the year after publication, spending increased to 27 US dollars per physician in Canada versus 23 US dollars per physician in the United States. In the absence of promotional activity for RALES in either country, publication of results was associated with more modest but similar increases of 2% per month (P = 0.001) in spironolactone use in both countries.

CONCLUSION

Publication of new evidence is associated with modest changes in practice. Promotional activity appears to increase the adoption of evidence. Rather than relying on the publication of articles and creation of guidelines, those wishing to accelerate the adoption of new evidence may need to undertake more active promotion.

Utilisation of coronary angiography after acute myocardial infarction in Ontario over time: have referral patterns changed?

OBJECTIVE

To examine how physicians in Ontario, Canada, have altered their referral patterns for coronary angiography after acute myocardial infarction (AMI) over time.

DESIGN

Retrospective analysis of multilinked administrative data.

SETTING

Province of Ontario, Canada.

PATIENTS

146 365 Ontario AMI patients hospitalised between 1 April 1992 and 31 March 1999.

MAIN OUTCOME MEASURES

Utilisation trends of coronary angiography among all patients, as well as within six subgroups: elderly (versus young), women (versus men), high (versus low) risk of 30 day mortality, high (versus low) socioeconomic status, cardiology (versus non-cardiology) attending physician specialty, and hospitals with (versus without) onsite revascularisation capacity. Cox proportional hazard models were adjusted for variations in patient, physician, and hospital characteristics over time.

RESULTS

Angiography rates in Ontario increased from 23.2% in 1992 to 35.5% in 1999 (p < 0.0001). Increases in utilisation of coronary angiography were most pronounced among the elderly (12.4-24.3% v 39.3-54.4% for non-elderly patients, p < 0.0001), the affluent (24.6-38.7% v 22.0-32.3% for less affluent patients, p = 0.01), and those tended to by cardiologists (32.0-47.1% v 20.3-30.1% for non-cardiology attending specialties, p < 0.0001) after adjusting for changes in baseline patient, physician, and hospital characteristics over time.

CONCLUSIONS

Despite universal health care availability, not all patients benefited equally from increases in service capacity for coronary angiography after AMI in Ontario. Wider implementation of data monitoring and explicit management systems may be required to ensure that appropriate utilisation of cardiac services is allocated to patients who are most in need.