Promoting Regular Mammography Screening II. Results From a Randomized Controlled Trial in US Women Veterans

Breast cancer is the second leading cause of cancer deaths in women in the United States (1). Evidence from randomized controlled trials shows that regular screening with mammography reduces mortality from breast cancer in women aged 50–74 years by approximately 23% (2) and that women older than 74 years benefit as well (3). To maximize the population benefit in terms of mortality reduction, women need to be screened every 1–2 years. Prevalence estimates from the National Health Interview Survey of mammography in women aged 40 years and older, as measured by self-report of recent use (within the past 2 years), increased from 30% to 70% between 1987 and 2000 (4). However, the prevalence of regular mammography—that is, consecutive, on-schedule mammograms—is lower than the prevalence of recent mammography. For example, a review of regional studies reported summary estimates of repeat mammography in women aged 50 years and older (using an interval of ≤15 months between mammograms); rates ranged from 30.7% (95% confidence interval [CI] = 17.5 to 43.9) in studies conducted before 1991 to 43.6% (95% CI = 35.0 to 52.5) in studies conducted from 1995 through 2001 (5). Thus, although the pattern of increase for repeat mammography was similar to that for recent mammography, the prevalence was lower. CONTEXT AND CAVEATS Prior knowledge Some behavioral interventions, especially those that include individually tailored messages, have been found to increase rates of one-time mammography screening. However, fewer studies have analyzed interventions to promote ongoing regular mammography. Study design The Project Healthy Outlook on the Mammography Experience trial compared rates of completion of two or more mammograms (“compliance”) among women randomly assigned to a tailored and targeted intervention, to a targeted intervention, and to a survey-only control group. Outcomes were evaluated by three decreasingly conservative analytic methods. Contributions An analytic approach that takes losses to follow-up into account may produce more conservative (less favorable) estimates of intervention effects. Only the least conservative analysis provided evidence that either intervention improved compliance compared with the survey-only control group. The absolute between-group difference ranged from 3% to 6%, depending on the analysis. Implications An intervention targeted to a broad group of women (in this case, women veterans) may work as well as one that is both tailored and targeted, although neither intervention was clearly superior to the control condition. Limitations The appropriate analytic method for a study of this type is not clear. The study did not have the statistical power to evaluate whether the modest intervention effects that were observed were statistically significant. It was possible to assess the validity of results based on self-reported mammography by reviewing medical records only for the subgroup of women veterans known to have ever used Veterans Healthcare Administration facilities. A longer follow-up may be necessary to evaluate compliance among women who have regular mammograms at intervals of more than 2 years. Throughout the 1980s and 1990s, many intervention trials were conducted to promote one-time mammography screening. Systematic reviews and meta-analyses have concluded that a variety of strategies are efficacious at increasing one-time mammography screening (6–15). Although the classification schemes varied, minimal interventions directed at patients (6,9–11,13) or providers (12–14) have been shown to increase screening. Meta-analyses also suggest that more intensive patient-directed interventions, including those using multiple strategies (eg, letter plus phone call), those tailored to an individual’s characteristics, and those based on theory, produced larger intervention effects than usual care or minimal interventions (6,10,11,16). In contrast, fewer studies have been conducted to evaluate strategies to increase regular screening (17). To evaluate two theory-based interventions to promote regular mammography screening, we performed Project HOME (Healthy Outlook on the Mammography Experience), a randomized controlled trial to promote regular mammography screening. At the time our trial was conducted, no published studies had examined the effects of an intervention on completion of two or more postintervention mammograms, although several studies had measured completion of a second on-schedule mammogram among women who had a recent preintervention mammogram [see, eg, (18–20)]. Since 2000, only five published studies have examined whether women completed two postintervention mammograms (21–25), and they are limited in several ways. All five studies were based on regional samples in the northeast United States. Only one study (22) was community based; the other four were conducted in health-care settings. As with most cancer screening intervention trials, these studies evaluated intervention efficacy—that is, they attempted to maximize internal validity, with less attention to external validity (26,27). All study samples were drawn from defined sampling frames; however, no comparisons were made between participants and eligible nonparticipants (eg, refusers and nonrespondents). Further, although most tested equivalence of study groups at baseline, only two (22,25) compared the final analyzed sample with study withdrawals. None analyzed the data using intention-to-treat (ITT) principles; only participants who completed the study and provided all relevant follow-up data were included in the outcome analyses. Although all studies tested theory-based personalized strategies such as telephone counseling (22,25) and/or tailored print materials (21,23,24), only two (23,24) compared interventions of different degrees of personalization and none compared targeted (designed for population subgroups) and tailored (designed for individual-level feedback) approaches to motivate women to obtain a mammogram. Project HOME, in addition to comparing a tailored and targeted intervention with a targeted-only intervention, goes beyond these earlier studies by attending to external validity, as well as internal validity, as described in the accompanying article by del Junco et al. (28). Specifically, we used a well-defined national sampling frame, the target population was randomly sampled, the study sample was tracked throughout the course of the study, and the data were analyzed using an ITT analysis in addition to more typical but decreasingly conservative analyses (29).