Table 3. Major limitations of the study.

MI: Myocardial infarction

Study	Major limitations
Desai et al. [9]	Only studied in-hospital odds of mortality, which leaves out outpatients or post-discharge odds of mortality in MI patients
Frost et al. [11]	Cannot rule out the possibility of unmeasured or residual confounding; because most of the patients with MI were on some medications before sustaining MI, so they might have received secondary prevention measures in a manner unrelated to marijuana use; the study was based on self-reported marijuana use, so there may be some exposure misclassification
Johnson-Sasso et al. [10]	Angiograms, laboratory tests, medications taken pre- or post-MI, and vital signs on admission were not available; no post-discharge data including long-term mortality and readmissions; the route, amount and frequency of marijuana use in each patient could not be determined, so a dose-response effect could not be established
Kenneth et al. [12]	The number of marijuana smokers was relatively small; follow-up was limited to approximately 4 years; could not prove cause and effect relationship