Table 1. Sample characteristics by selected years (n = 3757).

	2005		2008		2011
	n	%	n	%	n	%
Mean age, years
20–39 (reference)	313	8.33	313	8.33	313	8.33
40–65	2385	63.48	2385	63.48	2385	63.48
>65	1059	28.19	1059	28.19	1059	28.19
Sex, male	1977	52.62
Care continuity
No index	1484	39.5	1079	28.72	1025	27.28
Low	467	12.43	525	13.97	559	14.88
Medium	485	12.91	594	15.81	545	14.51
High (COCI = 1)	1321	35.16	1559	41.5	1628	43
Income, New Taiwan $
<20 000	1370	36.47	1035	27.55	1036	27.58
20 000–39 999	931	24.78	1221	32.5	1102	29.33
≥40 000	651	17.33	656	17.46	741	19.72
Fishermen/farmers, n	805	21.43	845	22.49	878	23.37
Area
Taipei	1253	33.35	1248	33.22	1251	33.3
North	487	12.96	482	12.83	489	13.02
Central	682	18.15	690	18.37	691	18.39
South	578	15.38	587	15.62	576	15.33
Kaohsiung-Pingdong	651	17.33	652	17.35	651	17.33
East	106	2.82	98	2.61	99	2.64
Diabetes Complications Severity Index
0	2674	71.17	2612	69.52	2322	61.8
1	647	17.22	669	17.81	780	20.76
≥2	436	11.61	476	12.67	655	17.43
Charlson Comorbidity Index
0–1	2193	58.37	2209	58.8	1903	50.65
2	957	25.47	859	22.86	935	24.89
≥3	607	16.16	689	18.34	919	24.46
Frequency of emergency room use
Mean/standard deviation	0.40/1.04		0.33/1.09		0.50/1.80
Min	0		0		0
Max	24		29		85
Frequency of emergency room use, DM-related
Mean/standard deviation	0.07/0.32		0.06/0.38		0.11/0.44
Min	0		0		0
Max	4		14		6

COCI, Continuity of Care Index; DM, diabetes mellitus.

Chi-squared was used for categorical variables and ANOVA for continuous variables.

Unit of observation: individual patient.

1 United States $ ≈ 30 New Taiwan $.