Context The benefits of cardiovascular therapies such as statins for secondary
prevention have been well documented, although they may not be optimally used
in patients most likely to benefit. Ideally, aggressiveness in the use of
these beneficial therapies should correlate with baseline cardiovascular risk.
Objective To examine the association between physicians' treatment aggressiveness
and baseline cardiovascular risk.
Design, Setting, and Patients Retrospective cohort study incorporating the use of multiple linked
health care administrative databases covering more than 1.4 million elderly
residents of Ontario. We included 396 077 patients aged 66 years or older
who had a history of cardiovascular disease or diabetes while undergoing medical
treatment and who were alive on April 1, 1998. Baseline cardiovascular risk
was derived using a risk-adjustment index in which we modeled probability
of death after 3 years of follow-up.
Main Outcome Measure Likelihood of statin use, stratified by baseline cardiovascular risk,
after adjusting for age, sex, socioeconomic status, and rural or urban residence.
Results Only 75 617 patients (19.1%) in this secondary prevention cohort
were prescribed statins. In patients 66 to 74 years old, the adjusted probabilities
of statin prescription were 37.7%, 26.7%, and 23.4% in the categories of low,
intermediate, and high baseline risk, respectively. The likelihood of statin
prescription was 6.4% lower (adjusted odds ratio, 0.94; 95% confidence interval,
0.93-0.95) for each year of increase in age and each 1% increase in predicted
3-year mortality risk. The influence of age also interacted synergistically
with baseline risk on the prescription of statins (P<.001).
Conclusions We found that prescription of statins diminished progressively as baseline
cardiovascular risk and future probability of death increased. Since the benefits
of a therapy are dependent on the baseline risk, the maximum benefits of statins
may not be fully realized until implementation of therapy includes patients
at highest risk.