Table 1. Demographic Characteristics of the Study Population Enrolled in an Insurance Plan by Duration of Enrollment, Gaps in Enrollment, and Number of Visits Coded for Heart Disease, Minneapolis, Minnesota, 2007–2008^a .

Length of Enrollment/Gap in Enrollment >31 Days	No. of Visits for Heart Diseaseb Based on Claims Data
Enrolled any time from August 1, 2007–July 31, 2008; N = 474,089; female, 52.4%; age, 49.4 (18.0)
Gap: n = 146,939; female, 50.2%; age, 46.1 (16.0)	None: n = 140,440; female, 53.9%; age, 44.5 (15.0)
	1 visit: n = 3,918; female, 38.6%; age, 60.6 (21.0)
	≥2 visits: n = 2,581; female, 40.5%; age, 64.6 (23.0)
No gap: n = 327,150; female, 53.4%; age, 51.0 (17.0)	None: n = 296,073; female, 56.3%; age, 45.8 (17.0)
	1 visit: n = 15,182; female, 47.1%; age, 62.5 (22.0)
	≥2 visits: n = 15,895; female, 50.6%; age, 68.3 (20.0)
Also enrolled on August 1, 2005; N = 272,348; female, 54.0%; age, 52.0 (18.0)
Gap: n = 40,174; female, 52.6%; age, 48.7 (18.0)	None; n = 37,179; female, 57.7%; age, 48.7 (18.0)
	1 visit: n = 1,601; female, 45.4%; age, 71.6 (24.0)
	≥2 visits: n = 1,394; female, 47.0%; age, 75.7 (22.0)
No gap: n = 232,174; female, 54.2%; age, 52.6 (17.0)	None: n = 207,195; female, 58.1%; age, 53.1 (17.0)
	1 visit: n = 11,782; female, 43.7%; age, 69.1 (21.0)
	≥2 visits: n = 13,197; female, 43.2%; age, 72.3 (19.0)

^a Ages are presented in years and as mean (interquartile range).

^b International Classification of Diseases, Ninth Revision, Clinical Modification codes 410–414, 420–429, or both.