Table 4: Calendar period of treatment in relation to insufficient cardiac monitoring and cardiotoxicity in patients with breast cancer who underwent treatment with adjuvant trastuzumab in Ontario from 2003 to 2009 (n = 3777)

Outcome	Calendar period, OR (95% CI)
Outcome	2003-2007	2008-2009
Insufficient monitoring
Model 1*	1 (Reference)	0.93 (0.74 to 1.16)
Cardiotoxicity
Model 1*	1 (Reference)	0.56 (0.45 to 0.70)
Model 2†	1 (Reference)	0.54 (0.42 to 0.69)

Note: OR = odds ratio.

*Model 1 was adjusted for age, Charlson Deyo index, previous heart failure, hypertension, previous myocardial infarction, diabetes mellitus, income, rural residence, annual hospital volume, cumulative physician volume, hospital clustering, physician clustering and Local Health Integration Network clustering.

†Model 2 was adjusted for all variables in model 1 and further adjusted for sufficiency of cardiac monitoring.