Systematic differences in validity of self-reported mammography behavior: A problem for intergroup comparisons?

Background Prior studies of recall accuracy for screening mammogram behavio r have examined relatively homogeneous groups. Data are limited on possible systematic group differences, so we evaluated women's recall accuracy in t wo separate care systems in one city. Methods. Women 50 to 70 years old with and without screening mammograms 10 to 14 months prior were identified from fiscal, clinic, and radiology recor ds at a military care system (MCS) and a county-funded system (CFS) for ind igents. Mammogram status was verified through radiology records. Women were excluded if mammograms were diagnostic, done for other than annual screeni ng, or had abnormal results. Interviewers blinded to mammogram status surve yed randomly selected eligible women. Results. For 62 screened/31 unscreened MCS women and 78 screened/61 unscree ned CFS women, specificity was similar, at 65 and 62%, respectively. In con trast, sensitivity varied significantly: 95% versus 79% (P = 0.011). Primar y ethonocultural groups were Euro-American (MCS-60%) and Mexican American ( CFS-85%)Although not different in specificity of recall (67% versus 61%), t hese major subgroups significantly differed insensitivity (97% versus 80%, P = 0.017), proportion of true negatives due to never having a mammogram (3 5% versus 57%, P = 0.003), and proportion with greater than or equal to hig h school education (78% versus 19%, P < 0.00001). Conclusion. Systematic differences in recall validity may exist and comprom ise the accuracy of intergroup comparisons. (C) 1999 American Health Founda tion and Academic Press.