Stratification schema for sampling of patients for chart review at each of the 8 sites

	Outcomes
	Prevalent CM/HF		Incident CM/HF		No CM/HF
Exposures	LVEF	No LVEF	LVEF	No LVEF	LVEF	No LVEF	Patient Count
Both Anthracycline and Trastuzumab	1	1	2	2	3	1	10
Either Anthracycline or Trastuzumab	1	1	2	2	3	1	10
Neither Anthracycline nor Trastuzumab	3	3	6	6	9	3	30
Patient Count	5	5	10	10	15	5	50

CM – Cardiomyopathy, HF – Heart failure, LVEF – Left ventricular ejection fraction measured