Table 4.

External validity assessment: secular trends in recent mammography screening history^* at baseline survey using self-report and Veterans Health Administration (VHA) records

	Coverage †		Compliance ‡
Independent variables	n (%)	P§	n (%)	P§
Baseline survey  respondents (self-  report) (n = 5525)
Group 1	947 (84.9)	.641	647 (58.0)	.538
Group 2	1005 (86.0)	.219	698 (59.7)	.825
Group 3 (referent)	950 (84.2)	Referent	669 (59.3)	Referent
Group 4 (baseline   delayed 1 y)∥	931 (85.3)	.436	618 (56.7)	.213
Group 5 (baseline   delayed 2 y)∥	839 (82.3)	.241	604 (59.2)	.985
Subgroup of those who  ever used VA health-  care services,  including baseline  survey respondents,  nonrespondents, and  refusals (VA  records) ¶ (n = 3676)
Group 1	169 (21.8)	.478	89 (11.5)	.689
Group 2	159 (21.9)	.521	87 (12.0)	.486
Group 3 (referent)	166 (23.3)	Referent	77 (10.8)	Referent
Group 4 (baseline   delayed 1 y)∥	176 (22.7)	.781	82 (10.6)	.884
Group 5 (baseline   delayed 2 y)∥	118 (17.2)	.004	61 (8.9)	.228

^*Recent mammography screening history was defined as having had one or more mammograms within the 30 months preceding the date of each group’s baseline survey. For self-report, baseline survey respondents reported the dates of their two most recent mammograms. For VHA records, mammogram procedure codes and dates between the years 1996 and 2005 were documented in Veterans Administration (VA) administrative databases, either the Patient Treatment File or the Outpatient Clinic File, for the subgroup of those who had ever used VA health-care services.

^†Coverage = at least one prior mammogram.

^‡Compliance = at least two prior mammograms 6–15 months apart.

^§From two-sided chi-square tests.

^∥Groups 4 and 5 received the baseline survey 1 and 2 years, respectively, after groups 1–3.

^¶Excludes decedents, males, and those born after June 1, 1948, as ascertained by linkages with available electronic databases.