Table 2.

Association of Metformin Use with Markers of Emphysema Progression within COPDGene

Outcome	Difference between Follow-up and Baseline		Difference-in-Difference*	P Value
	Metformin Users [Units (95% CI)]	Metformin Nonusers [Units (95% CI)]
Overall cohort (n = 1,687)
Percentage of emphysema	1.4 (0.62 to 2.2)	2.3 (2.1 to 2.6)	−0.92 (−1.7 to −0.14)	0.02
Adjusted lung density, g/L	−2.7 (−4.5 to −0.97)	−5.0 (−5.5 to −4.4)	2.2 (0.43 to 4.0)	0.01
Persistent use (n = 1,540)†
Percentage of emphysema	0.87 (−0.06 to 1.8)	2.4 (2.1 to 2.7)	−1.5 (−2.5 to −0.59)	<0.01
Adjusted lung density, g/L	−2.9 (−4.6 to −0.38)	−5.1 (−5.7 to −4.5)	2.6 (0.48 to 4.7)	0.02

Definition of abbreviations: CI = confidence interval; CT = computed tomography; COPDGene = Genetic Epidemiology of Chronic Obstructive Pulmonary Disease.

^*Adjusted for age, sex, race, smoking status, use of an ACE (angiotensin-converting enzyme) or angiotensin II receptor blocker, comorbidity count, time-varying body mass index, CT scanner model, and pack-years of smoking.

^†Subset of participants who were consistent users or nonusers of metformin at baseline and follow-up.