Table 4.

Additional analyses for outcomes in patients with metformin use versus no-use or sulfonylurea.

Variables	Outcome			cHR	(95% CI)	aHRa	(95% CI)
	N	PY	IR
Bacterial pneumonia
Active comparator anaylsis
Sulfonylurea use	862	122,874	7.02	1.00	(Reference)	1.00	(Reference)
Metformin use	592	124,602	4.75	0.68	(0.61, 0.75)***	0.65	(0.59, 0.73)***
Time-varying exposure of metfomin
Nonuse of metformin				1.00	(Reference)	1.00	(Reference)
Metformin use				0.9	(0.838,0.967)**	0.92	(0.855, 0.988)*
Age groups of metfomin users
Nonuse of metformin	2046	246,785	8.29	1.00	(Reference)	1.00	(Reference)
Age groups of metformin users
20–40	50	33,180	1.51	1.93	(1.37, 2.73)***	1.81	(1.28, 2.57)***
41–60	369	115,250	3.20	1.13	(0.99, 1.3)	1.09	(0.95, 1.26)
61–80	1627	98,356	16.54	0.8	(0.74, 0.86)***	0.84	(0.78, 0.9)***
Cumulative dose of metfomin use
Nonuse of metformin	2046	246,785	8.29	1.00	(Reference)	1.00	(Reference)
Dose of metfomin (mg/day)
< 400	689	80,598	8.55	1.15	(1.06, 1.26)**	1.09	(1, 1.19)
400–799	439	58,963	7.45	0.95	(0.86, 1.06)	0.98	(0.88, 1.08)
800–1199	319	46,291	6.89	0.80	(0.71, 0.9)***	0.81	(0.72, 0.91)***
≧ 1200	538	76,228	7.06	0.74	(0.67, 0.82)***	0.76	(0.69, 0.84)***
Acute exacerbation of COPD
Nonuse of metformin	2611	204,119	12.79	1	(Reference)	1.00	(Reference)
Metformin use	2703	214,200	12.62	0.98	(0.93, 1.04)	0.97	(0.92, 1.02)

PY person-years, IR incidence rate, per 1000 person-years, cHR crude hazard ratio, aHR adjusted hazard ratio, COPD chronic obstructive pulmonary disease.

*P < .05, **P < .01, ***P < .001.

aHR^a, multivariable analysis adjusted for sex, age, comorbidities, CCI, DCSI scores, insulin, statin, aspirin, item and number of oral antidiabetic drugs.