(b).

Advanced stage at diagnosis IPTW
Unadjusted odds ratios and 95% confidence intervals
	OR	95% CI	Sig.
Metformin
Yes	0.69	[0.49, 0.95]	∗
No	Ref.
Adjusted odds ratios and 95% confidence intervals
	AOR	95% CI	Sig.
Metformin
Yes	0.68	[0.48, 0.97]	∗
No	Ref.

Notes: based on the data of 2,652 elderly men aged 66 years and older diagnosed with prostate cancer between 2008 and 2009 using a surveillance, epidemiology, and end-results- (SEER-) Medicare linked data. % is weighted percentage for IPTW. Significant differences are based on the log-likelihood test using a logistic regression with IPTW weights. Adjusted model controlled for predisposing, enabling, need, and external environment related factors.

IPTW: inverse probabilities treatment weights; PSA: prostate specific antigen level; PCP: primary care physician visit; Sig.: level of significance; ^∗∗∗ p < 0.001; ^∗∗0.001 ≤ p < 0.01; ^∗0.01 ≤ p < 0.05.