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Response to letters
Submit responseBrodersen et al.’s letter refers to their review showing long-term effects of false-positives in only two studies1. Their findings, paired with their concerns about the validity of measures used, caused them to conclude that available measures were inadequate to detect long-term effects of false positives. We believe that their conclusion is incorrect, resulting from their decision to exclude many ad hoc measures in order to focus on measures for which some information on validation was available. In our systematic review of twenty-three studies meeting stringent quality criteria, we found that false-positive mammograms were consistently associated with poorer long-term outcomes on breast-cancer- specific measures of well-being (e.g., distress and anxiety)2. We chose to include the breast cancer-specific measures, despite the fact that most were ad hoc, because we expected that they were more likely to detect effects of breast cancer screening than more general well-being measures with established validity. Although it is reasonable to be concerned that ad hoc measures could present problems for comparisons across studies, research supports the use of such measures to assess subclinical distress. In our systematic review, studies that used previously validated general distress measures that were not specific to breast cancer showed no discernable pattern of long-term effects of false positives. Thus, it appears that the more important issue is to make sure that the effects of false positives are assessed with breast-cancer specific measures of distress. We would welcome the development of a better measure of breast cancer-specific distress that improves upon existing measures by establishing convergent and discriminant validity. Brodersen et al. appear to have misunderstood our finding of different long-term effects of false-positive mammograms on return for mammography in Europe relative to America. Although overall return for mammography was higher in the European studies (85%) than in the US studies (60%), our paper focused on the finding that false positives increased return for mammography in the United States (RR=1.07, 95%CI:1.02-1.12) but not in Europe (RR=.97, 95%CI:.93-1.01). While our rates of return are similar to ones previously published5, we believe that our paper’s more important contribution is to highlight the real and lasting effects of false- positive mammograms. We appreciate the thoughtful comments by Geller et al. that more accurately characterize mammography screening guidelines for European women aged 40 to 49.
References
1 Brodersen J, Thorsen H, Cockburn J. The adequacy of measurement of short and long-term consequences of false-positive screening mammography. Journal of Medical Screening 2004; 11(1):39-44.
2 Brewer NT, Salz T, Lillie SE. Systematic review: The long-term effects of false-positive mammograms. Annals of Internal Medicine 2007; 146(7):502-510.
3 Harris RP, Helfand M, Woolf SH, Lohr KN, Mulrow CD, Teutsch SM et al. Current methods of the US Preventive Services Task Force - A review of the process. American Journal of Preventive Medicine 2001; 20(3):21-35.
4 Nisbett RE, Wilson TD. Telling More Than We Can Know - Verbal Reports on Mental Processes. Psychological Review 1977; 84(3):231-259.
5 Clark MA, Rakowski W, Bonacore LB. Repeat mammography: Prevalence estimates and considerations for assessment. Annals of Behavioral Medicine 2003; 26(3):201-211.
Conflict of Interest:
None declared
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Any current conclusions about the psychosocial long-term consequences must remain tentative
Submit responseWe acknowledge the authors work on the systematic review: the long- term effects of false-positive mammography.[1] Conducting at the moment several projects on psychosocial consequences of having a false-positive cancer screening result we would like to contribute with some of the knowledge gained from our research.
In a systematic review about the adequacy of measurement of short and long-term consequences of false-positive screening mammography we concluded: “Given the inadequacy of the measurement instruments used, any current conclusions about the long-term consequences of false-positive results of screening mammography must remain tentative.”[2] In our recent research we have found that even the most adequate measure of short-term psychosocial consequences of false-positive screening mammography has lack of content validity in the setting of abnormal screening mammography.[3] Therefore, we are surprised that Brewer et al’s do not discuss the invalidity of the results on the psychosocial aspects and health related quality of life aspects reported in their review.
We have conducted six focus group interviews with women who had all been screened for breast cancer in the year prior to the interviews and all had experienced being told that their screening mammography was abnormal. All had also undergone additional medical procedures before the cancer suspicion was disproved. Based on the results from the group interviews we have developed a questionnaire specifically measuring long- term consequences of false-positive screening mammography. The new instrument has been validated using Item Response Theory: the Rasch model (until now published in a PhD-thesis).[4] We are currently using this new measure in a Danish survey. The instrument has been translated into English, Dutch and Norwegian and these versions will probably be used in future surveys. This will hopefully bring new more detailed and more valid information about the possible psychosocial long-term consequences of false-positive screening mammography.
Brewer et al find national differences of participation rates at breast cancer screening. In countries with national mammography programmes where the government authorities invite to screening this has been shown to induce the feeling that participation in screening is more a “duty- order”, something that is an obligation, rather than a voluntary offer/proposal.[5;6] This might be one plausible explanations to the higher participation rates in breast cancer screening in Europe compared to U.S. Most of the women participating in our focus group interviews stated that having a false-positive screening mammography had frighten them so much that they did not dare to stay away from the next screening round.
Reference List
1. Brewer NT, Salz T, Lillie SE. Systematic Review: The Long-Term Effects of False-Positive Mammograms. Ann Intern Med 2007;146:502-10.
2. Brodersen J, Thorsen H, Cockburn J. The adequacy of measurement of short and long-term consequences of false-positive screening mammography. Journal of Medical Screening 2004;11:39-44.
3. Brodersen J, Thorsen H, Kreiner S. Validation of a condition- specific measure for women having an abnormal screening mammography. Value in Health 2007;10.
4. Brodersen J. Measuring psychosocial consequences of false-positive screening results - breast cancer as an example. Department of General Practice, Institute of Public Health, Faculty of Health Sciences, University of Copenhagen: Månedsskrift for Praktisk Lægegerning, Copenhagen. ISBN: 87-88638-36-7, 2006.
5. Lunde IM. "Jeg håber det bedste..." [Danish]. Ringkøbing: Den Medicinske Forskningsenhed, Ringkøbing, 1997.
6. Lou S, Dahl K, Risor MB, Hvidman LE, Thomsen SG, Jorgensen FS et al. A qualitative study of pregnant women's choice of nuchal translucency measurement. Ugeskr.Laeger. 2007;169:914-8.
Conflict of Interest:
None declared
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Most women start screening at age 50
Submit responseI read this article with great interest. False positive mammography happens frequently in the United States and it is important to understand the ramifications of these test results. However, I find the opening sentence misleading “Regular mammography has become part of routine health care in the developed world for women 40 years of age and older.” Most women in the developed world do not start breast cancer screening at age 40 and to open the article with this statement adds to the confusion about what is recommended and practiced throughout the world. According to the International Breast Cancer Screening Network’s 2002 survey, only the United States, Iceland, Sweden and Uruguay offer screening at age 40. The fifteen other member countries either start at 45 (2 countries) or 50 (http://appliedresearch.cancer.gov/ibsn/data/age.html).
Conflict of Interest:
None declared