TABLE 4.

Sample attrition and data continuity among patients with type 2 diabetes mellitus in the Integrated Medical Database of National Taiwan University Hospital.

	Initial sample size, n = 38,134
	Step 1: Number of patients eligible for analysis	Sample retention from initial sample to Step 1 (%)	Step 2: Number of patients with continuous baseline and/or follow-up data	Sample retention from Step 1 to Step 2 (%)	Overall sample retention from initial sample to Step 2 (%)
Baseline only
At least 6-months baseline	18,649	49	7,621	41	20
At least 12-months baseline	16,291	43	5,015	31	13
Follow-up only
At least 12-months follow-up	35,051	92	27,663	79	73
At least 24-months follow-up	31,538	83	22,297	71	58
At least 60-months follow-up	20,064	53	11,883	59	31
Baseline + Follow-up
At least 6-months baseline + at least 24-months follow-up	11,873	31	3,697	31	10
At least 12-months baseline + at least 24-months follow-up	9,695	25	2,439	25	6