Are benefits and harms in mammography screening given equal attention in scientific articles? A cross-sectional study

Karsten Juhl Jørgensen,Anders Klahn,Peter C Gøtzsche

doi:10.1186/1741-7015-5-12

Abstract

BackgroundThe CONSORT statement specifies the need for a balanced presentation of both benefits and harms of medical interventions in trial reports. However, invitations to screening and newspaper articles often emphasize benefits and downplay or omit harms, and it is known that scientific articles can be influenced by conflicts of interest. We wanted to determine if a similar imbalance occurs in scientific articles on mammography screening and if it is related to author affiliation.MethodsWe searched PubMed in April 2005 for articles on mammography screening that mentioned a benefit or a harm and that were published in 2004 in English. Data extraction was performed by three independent investigators, two unblinded and one blinded for article contents, and author names and affiliation, as appropriate. The extracted data were compared and discrepancies resolved by two investigators in a combined analysis. We defined three groups of authors: (1) authors in specialties unrelated to mammography screening, (2) authors in screening-affiliated specialties (radiology or breast cancer surgery) who were not working with screening, or authors funded by cancer charities, and (3) authors (at least one) working directly with mammography screening programmes. We used a data extraction sheet with 17 items described as important benefits and harms in the 2002 WHO/IARC-report on breast cancer screening.ResultsWe identified 854 articles, and 143 were eligible for the study. Most were original research. Benefits were mentioned more often than harms (96% vs 62%, P < 0.001). Fifty-five (38%) articles mentioned only benefits, whereas seven (5%) mentioned only harms (P < 0.001). Overdiagnosis was mentioned in 35 articles (24%), but was more often downplayed or rejected in articles that had authors working with screening, (6/15; 40%) compared with authors affiliated by specialty or funding (1/6; 17%), or authors unrelated with screening (1/14; 7%) (P = 0.03). Benefits in terms of reduced breast cancer mortality were mentioned in 109 (76%) articles, and was more often provided as a relative risk reduction than an absolute risk reduction, where quantified (45 articles (31%) versus 6 articles (3%) (P < 0.001)).ConclusionScientific articles tend to emphasize the major benefits of mammography screening over its major harms. This imbalance is related to the authors' affiliation.

Highlights

The CONSORT statement specifies the need for a balanced presentation of both benefits and harms of medical interventions in trial reports
It is essential to consider both benefits and harms carefully when the merits of any intervention are discussed in the medical literature. This was recently emphasised in an extension to the CONSORT statement on reporting randomised trials [1], but it applies to other scientific work, and to information material directed towards healthy citizens and patients [2]
We examined articles in medical journals discussing mammography screening to see if they gave equal attention to benefits and harms, as we suspected that information materials and newspaper articles would reflect their presentation of the issues

Summary

Introduction

The CONSORT statement specifies the need for a balanced presentation of both benefits and harms of medical interventions in trial reports. It is essential to consider both benefits and harms carefully when the merits of any intervention are discussed in the medical literature This was recently emphasised in an extension to the CONSORT statement on reporting randomised trials [1], but it applies to other scientific work, and to information material directed towards healthy citizens and patients [2]. A similar bias has been found in newspaper articles on breast cancer screening [8] This focus on benefits is contrary to the ethical imperative that those subjected to any preventive measure or treatment should receive unbiased information [2], and it is troublesome in screening, as this is directed towards healthy individuals, not patients seeking treatment. The 2002 WHO/IARC report on breast cancer screening notes that "...the vast majority of women undergoing screening do not have breast cancer at the time of the examination, and these women cannot derive a direct health benefit from screening; they can only be harmed" [9]

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