Effect of Continuity of Care on Emergency Department Visits in Elderly Patients with Asthma in Taiwan

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Figure 1.
Diagrammatic representation of the patient populations. *The results of analysis among those patients are demonstrated in Appendix Table 1. COC, continuity of care.
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Figure 2.
The schematic diagram of the time frame. CCI, Charlson comorbidity index; COC, continuity of care; COCI, continuity of care index; COPD, chronic obstructive pulmonary disease; ED, emergency department.

Table 1.

Characteristics of Subjects (N = 3395) by Continuity of Care Index Group

Characteristics	Subjects	Level of COCI (%)			P Value^*
Characteristics	Subjects	<0.47 (n = 826)	0.47–0.99 (n = 906)	1 (n = 1663)	P Value^*
Total	100.0	24.3	26.7	49.0
Patient characteristics at baseline
Sex					.111
Female	49.5	49.9	52.1	47.8
Male	50.5	50.1	47.9	52.2
Age, years (mean ± SD)	74.0 (6.2)	73.7 (6.2)	74.0 (6.0)	74.2 (6.2)	.155
Insurance premium (US$)					.147
<667	56.3	56.8	57.5	55.4
667–1333	27.1	26.3	24.5	28.9
>1333	16.6	17.0	18.0	15.7
P4P participating status					.867
Not a participant	89.7	90.1	89.3	89.7
Participant	10.3	9.9	10.7	10.3
Medical conditions
In a preceding year
CCI					.094
0	17.0	17.1	14.4	18.3
1–2	11.9	12.8	12.4	11.1
≥3	71.1	70.1	73.3	70.5
COPD					.004
No	75.3	72.0	73.7	77.7
Yes	24.7	28.0	26.3	22.3
In the COC period
Ambulatory visits for asthma, n					<.001
4–12	80.5	82.7	72.6	83.8
13–24	17.3	14.9	24.1	14.9
≥25	2.2	2.4	3.3	1.4
Hospitalization for asthma					<.001
No	97.0	95.4	95.6	98.5
Yes	3.0	4.6	4.4	1.5
ED visits for asthma					<.001
No	94.5	91.0	93.5	96.8
Yes	5.5	9.0	6.5	3.2
Healthcare outcome
ED visits for asthma					<.001
No	96.5	93.9	96.7	97.8
Yes	3.5	6.1	3.3	2.2

Data are percentages unless otherwise indicate.
↵* χ² test for difference in the level of Continuity of Care Index (COCI).
CCI, Charlson comorbidity index; COPD, chronic obstructive pulmonary disease; ED, emergency department; P4P, pay for performance; SD, standard deviation.

Table 2.

Incidence of Emergency Department Visits Across Continuity of Care Index Groups (n = 3395)

Variables	Total (n = 3395)	Level of COCI			P for trend^*
Variables	Total (n = 3395)	<0.47 (n = 826)	0.47–0.99 (n = 906)	1 (n = 1663)	P for trend^*
Overall	3.45	6.05	3.31	2.22	<.01
Patient characteristics at baseline
Sex
Female	1.33	2.18	1.43	0.84	<.01
Male	2.12	3.87	1.88	1.38	<.01
Insurance premiums (US$)
<667	2.06	3.75	2.21	1.14	<.01
667–1333	0.97	1.57	0.77	0.78	.09
≥1333	0.41	0.73	0.33	0.30	.19
P4P participating status
Not a participant	3.15	5.45	3.09	2.04	<.01
Participant	0.29	0.61	0.22	0.18	.12
Medical conditions
In a preceding year
CCI
0	0.38	0.61	0.22	0.36	.50
1–2	0.12	0.12	0.22	0.06	.78
≥3	2.95	5.33	2.87	1.80	<.01
COPD
No	1.77	2.78	1.99	1.14	<.01
Yes	1.68	3.27	1.32	1.08	<.01
In the COC period
Ambulatory visits for asthma, n
4–12	2.09	3.51	1.77	1.56	<.01
13–24	1.12	2.06	1.32	0.54	<.01
≥25	0.24	0.48	0.22	0.12	.13
Hospitalization for asthma
No	3.15	5.33	3.31	1.98	<.01
Yes	0.29	0.73	0.00	0.24	.12
ED visits for asthma
No	2.36	3.63	2.43	1.68	<.01
Yes	1.09	2.42	0.88	0.54	<.01

↵* Cochran-Armitage trend test.
CCI, Charlson Comorbidity Index; COCI, continuity of care index; COPD, chronic obstructive pulmonary disease; ED, emergency department; P4P, pay for performance.

Table 3.

Factors Associated with Emergency Department Visits for Asthma Using Cox Models (n = 3395)

Variables	Crude Model		Adjusted model
Variables	HR	95% CI	HR	95% CI
COCI
1 (Reference)	1.00		1.00
0.47–0.99	1.50	0.92–2.42	1.15	0.70–1.87
<0.47	2.78	1.81–4.25	2.11	1.37–3.25
Patient characteristics at baseline
Sex
Female (reference)	1.00		1.00
Male	1.58	1.09–2.30	1.29	0.88–1.90
Age (years)	1.00	0.97–1.03	0.98	0.95–1.01
Insurance premium (US$)
<667 (Reference)	1.00		1.00
667–1333	0.98	0.65–1.48	1.13	0.74–1.72
≥1333	0.67	0.38–1.19	0.94	0.52–1.69
P4P participating status
Not participating (reference)	1.00		1.00
Participating	0.81	0.42–1.55	0.78	0.40–1.50
Medical conditions
In a previous year
CCI
0 (Reference)	1.00		1.00
1–2	0.44	0.14–1.34	0.37	0.12–1.15
≥3	1.85	1.04–3.29	1.00	0.53–1.87
COPD
No (reference)
Yes	2.97	2.07–4.27	2.20	1.46–3.30
In the COC period
Ambulatory visits for asthma, n
4–12 (Reference)	1.00		1.00
13–24	2.55	1.72–3.78	2.24	1.49–3.36
≥25	4.40	2.12–9.15	3.03	1.44–6.39
Hospitalization for asthma
No (reference)	1.00		1.00
Yes	3.08	1.61–5.89	1.00	0.50–1.99
ED visits for asthma
No (reference)	1.00		1.00
Yes	8.89	6.02–13.13	6.69	4.40–10.17

CCI, Charlson Comorbidity Index; CI, confidence interval; COCI, continuity of care index; COPD, chronic obstructive pulmonary disease; ED, emergency department; HR, hazard ratio; P4P, pay for performance.

Appendix Table 1.

Factors Associated with Emergency Department Visits for Asthma Using Cox Models (N = 7578)

Variables	Crude Model		Adjusted Model
Variables	HR	95% CI	HR	95% CI
COCI
1 (Reference)	1.00		1.00
0.47–0.99	2.03	1.34–3.09	1.21	0.76–1.91
<0.47	2.73	1.99–3.74	2.11	1.52–2.92
Patient characteristics at baseline
Sex
Female (4eference)	1.00		1.00
Male	1.49	1.11–1.99	1.27	0.94–1.72
Age (years)	1.01	0.99–1.03	1.00	0.97–1.02
Insurance premium (US$)
<667 (Reference)	1.00		1.00
667–1333	0.80	0.57–1.11	0.92	0.66–1.28
≥1333	0.65	0.42–1.02	0.85	0.54–1.34
Asthma P4P program
Not enrolled (reference)	1.00		1.00
Enrolled	1.08	0.57–2.04	0.83	0.43–1.60
Medical conditions
In a previous year
CCI
0 (Reference)	1.00		1.00
1–2	1.21	0.65–2.26	0.84	0.41–1.73
≥3	2.28	1.69–3.06	1.39	0.86–2.24
COPD
No (reference)	1.00		1.00
Yes	4.81	3.39–6.82	2.91	1.99–4.25
In the COC period
Ambulatory visits, n
4–12 (Reference)	1.00		1.00
13–24	2.55	1.72–3.78	2.12	1.42–3.19
≥25	0.70	0.50–0.96	1.12	0.69–1.84
Hospitalization
No (reference)	1.00		1.00
Yes	5.00	2.95–8.48	1.36	0.76–2.41
ED visits
No (reference)	1.00		1.00
Yes	10.42	7.47–14.54	6.09	4.19–8.85

CCI, Charlson Comorbidity Index; CI, confidence interval; COCI, continuity of care index; COPD, chronic obstructive pulmonary disease; ED, emergency department; HR, hazard ratio; P4P, pay for performance.