Letter to the Editor
Letter Regarding the Impact of U.S. Preventive Services Task Force Recommendations in Breast Cancer Screening Trends Dehkordy et al.1 performed an analysis of 4 years of data from the Behavioral Risk Factor Surveillance Survey (BRFSS) comparing screening mammography rates prior to and after the U.S. Preventive Services Task Force’s (USPSTF’s) 2009 revisions to its breast cancer screening guidelines, which withdrew recommendations that women aged 40 49 years have biennial mammograms.2 Dehkordy and colleagues’ analysis ﬁnds that mammography screening rates decreased from 2007 to 2012, whereas screening initiation rates at age 40 years increased during that period. They conclude that the “data support no perceptible change in … screening … within 3 years of the USPSTF guideline revision.” However, any interpretation of these assessments must be made with caution. The methodology used to conduct the BRFSS was updated starting with the 2011 survey.3 Prior to that year, the BRFSS was conducted as a landline-only telephone survey and was published with post-stratiﬁcation weights that adjusted for a limited set of demographic differences between survey respondents and state populations. In 2011, the BRFSS adopted a sampling frame that added mobile phone only households. Furthermore, they adopted a new method for calculating survey weights called “raking,” an iterative process designed to reduce bias by adjusting for a greater range of respondent characteristics than is possible under post-stratiﬁcation weighting, thus better informing the relationship between survey respondents and the population of interest. Most importantly, the raking methodology accounts for telephone ownership. These methodologic changes were necessary to maintain the relevance of BRFSS data as communications and statistical technology evolved. The inclusion of mobile phone only households alters the panel of respondents in important ways that are not fully accounted for by survey weights, in particular by increasing the representation of low-SES and younger individuals.3,4 These groups are more likely to engage in risky health behaviors and less likely to participate in preventive care, such as screenings.5 Although survey weights based on raking should improve the accuracy of state and national estimates based on BRFSS data, they nevertheless change the
& 2016 American Journal of Preventive Medicine
representativeness of a given respondent relative to what would have been calculated using post-stratiﬁcation weights.3,4 Dehkordy et al.1 make no mention of the 2011 change in BRFSS methodology or its potential impact on calculated mammography rates for 2012. They cite a report from CDC that details these changes,3 but only in referencing details of the BRFSS, not in discussing potential limitations to their ﬁndings. The changes made to BRFSS sampling methodology are an important step forward. Unfortunately, they occurred at a particularly inopportune time, coinciding not only with changes in the USPSTF mammography guidelines, but also with key provisions of the Affordable Care Act, which mandated insurance coverage of all preventive services graded A or B by the USPSTF.6 This substantially complicates efforts to track key targets of the Affordable Care Act using the BRFSS, a major source of data on preventive services use at the state level. Answers to these and similar policy questions will be best derived from other data sources. Douglas E. Levy, PhD Mongan Institute for Health Policy, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts http://dx.doi.org/10.1016/j.amepre.2015.09.020
References 1. Dehkordy SF, Hall KS, Roach AL, Rothman ED, Dalton VK, Carlos RC. Trends in breast cancer screening: impact of U.S. Preventive Services Task Force Recommendations. Am J Prev Med. 2015;49(3):419–422. http://dx.doi.org/10.1016/j.amepre.2015.02.017. 2. U.S. Preventive Services Task Force. Screening for breast cancer: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med. 2009;151(10):716–726. http://dx.doi.org/10.7326/ 0003-4819-151-10-200911170-00008. 3. Pieranuzzi C, Town M, Garvin W, Shaw F, Balluz L. Methodologic changes in the Behavioral Risk Factor Surveillance System in 2011 and potential effects on prevalence estimates. MMWR Morbid Mortal Wkly Rep. 2012;61(22):410–413. 4. Pennsylvania Health Statistics. Changes in the BRFSS weighting methodology: an explanation of the effects of the introduction of raked weighting on BRFSS data in Pennsylvania. 2012. www.statistics.health. pa.gov/MyHealthStatistics/BehavioralStatistics/BehavioralRisksSub-State/ Documents/BRFSS_Weighting_Methodology(2012).pdf. Accessed August 20, 2015. 5. National Center for Health Statistics. Health, United States, 2014: with special feature on adults aged 55 64. www.cdc.gov/nchs/data/hus/ hus14.pdf. Accessed August 21, 2015. 6. Patient Protection and Affordable Care Act: U.S.C. 42 §2713 Coverage of Preventive Services. 2010.
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