For a study, researchers sought to examine whether or not morphine was linked to an increased risk of adverse clinical events in ST-elevation myocardial infarction (STEMI) patients treated with fibrinolytic treatment and either clopidogrel or ticagrelor. The Ticagrelor in Patients with ST Elevation Myocardial Infarction Treated with Pharmacological Thrombolysis (TREAT) trial involved the random administration of clopidogrel or ticagrelor to 3,799 patients who had ST-elevation myocardial infarction and were being treated with fibrinolysis. The decision to administer morphine was left entirely up to the treating physicians. Investigators examined clinical outcomes in the study based on the usage of morphine and the timing of when it was administered, which were pre-specified criteria. The results were broken down into groups according to the randomized treatments received. A multivariable analysis was carried out using the weighting known as inverse probability treatment weighting (IPTW). About 53% of patients were given morphine for their pain. Morphine use was related to a higher risk of reinfarction after 7 days (HR=4.9, P=.0006) and 30 days (HR=1.7, P=.04), as well as a decreased risk of significant bleeding (HR=0.37, P=.006), when the data were adjusted using the IPTW weighting method. At no time was there a statistically significant difference in the death rate. Morphine use was related to a greater risk of early reinfarction and a reduced risk of significant bleeding among patients treated for STEMI with fibrinolytic treatment. Still, there was no difference in mortality rate between the 2 groups.