Table 2.

Incidence of hospitalized and outpatient heart failure by length of look-back period, ARIC cohort members enrolled in Medicare Fee-for-Service, 2000–2012 (N = 9568)

Look-back period (monthsb)	Hospitalized heart failure				Outpatient heart failure
	428.xx in the primary position		428.xx in any position		Observed incident outpatient HF	Incidence ratec
	Observed incident hospitalized HF	Incidence ratec	Observed incident hospitalized HF	Incidence ratec
6	609	11.20	1255	24.15	549	10.46
12	608	11.18	1223	23.54	507	9.67
18	598	11.00	1190	22.91	473	9.03
24	591	10.87	1161	22.37	448	8.56
30	583	10.72	1139	21.95	431	8.24
36a	577	10.61	1112	21.44	414	7.92

^aReferent

^bMonths available prior to index date

^cPer 1,000 person years