Exhibit 2. Annualized Emergency Department (ED) Visits In Prior, Index, And Subsequent Years.

	Number of ED visits in index year (2007)
	1	2	3-4	5-6	7-9	10-14	15+	All
Number of annualized ED visits
2 years prior	0.59	0.90	1.34	1.98	2.74	4.33	11.84	1.06
1 year prior	0.39	0.63	1.03	1.68	2.58	4.49	13.78	0.83
Index year	1.15	2.16	3.52	5.55	7.90	11.69	27.30	2.62
1 year after	0.65	1.04	1.65	2.63	3.99	6.47	18.47	1.36
2 years after	0.71	1.07	1.64	2.46	3.58	5.57	15.98	1.34
Number of EDs visited, index year	1.00	1.38	1.74	2.14	2.57	3.15	5.00	1.39
Primary diagnosis, visits in index year
Injury	18.0%	14.8%	12.2%	10.0%	8.6%	8.1%	5.9%	12.6%
Chronic condition	5.0	5.7	6.7	7.6	8.9	10.3	12.4	7.0
Substance use	1.6	1.7	2.2	3.2	4.6	7.6	20.0	3.8
Mental illness	2.7	3.0	3.4	4.2	5.1	6.2	5.9	3.8
Nonemergenta	27.3	27.9	28.1	27.7	26.5	24.4	19.4	26.9
Emergent, primary care treatablea	22.6	22.9	22.9	21.9	20.9	19.5	17.0	21.9
Emergent, preventable or avoidablea	5.8	6.7	7.8	8.6	9.7	11.0	11.2	7.9
Diagnoses 1–3, visits in index yearb
Substance use	2.3%	2.6%	3.3%	4.6%	6.3%	10.0%	24.1%	5.2%
Mental illness	3.4	3.9	4.5	5.6	6.7	8.2	8.1	4.9
Frequent users, index year and 2 years after
3+ visits each year	0.0%	0.0%	7.0%	16.0%	27.0%	42.0%	63.0%	4.0%
5+ visits each year	0.0	0.0	0.0	5.0	12.0	25.0	51.0	1.0

Source Authors' analysis of New York City Medicaid claims and encounter data. Note Visit rates are annualized based on the number of months a patient was eligible for Medicaid in a given year.

^aAccording to the New York University ED profiling algorithm (see Note 24 in text).

^bIncludes principal diagnosis and two secondary diagnosis fields.