Figure 4).

The adjusted probability of reperfusion therapy according to baseline risk and the number of pre-existing conditions. The number of pre-existing conditions represents the cumulative sum of all cardiac and noncardiac comorbid conditions, and is stratified into two subgroups: those with no or one pre-existing condition and those with two or more pre-existing conditions. Baseline risk (expected 30-day mortality) was derived from the risk adjustment index by Morrow et al (22). The probability of reperfusion therapy is also adjusted for age, sex, socioeconomic status, ethnicity, hospital type, rural-urban status and hospital arrival times. P=0.03 for the effects of baseline risk; P<0.01 for the effect of the number of pre-existing conditions