Dataset Information

Differential Use of Screening Mammography in Older Women Initiating Metformin versus Sulfonylurea.

ABSTRACT:

Purpose

Differential use of screening mammography may lead to biased detection of breast cancer. This study aimed to compare receipt of screening mammography and the incidence of screen-detected breast cancer between metformin and sulfonylurea initiators.

Methods

We used 2006-2014 US Medicare claims to identify initiators of metformin or sulfonylurea aged 65+ years continuously enrolled in Parts A/B for ≥2 years pre-initiation and ≥2 years post-initiation. We reported frequencies of screening mammograms and screen-detected breast cancer in 1 year pre-initiation among all cohort members and in 1 year post-initiation among cancer-free cohort members. Weighted screening risk differences (RDs) were estimated comparing metformin to sulfonylurea group.

Results

We identified 41,436 and 13,367 initiators of metformin and sulfonylurea, 35% and 24% of which had ≥1 screening mammogram in 1 year pre-initiation (weighted RD: 6 percentage points; 95% CI: 5 to 7), respectively. The weighted RD for screen-detected breast cancer associated with metformin was 0.00 percentage points (95% CI: -0.09 to 0.09). Among cancer-free cohort members, metformin initiators had 5 percentage points (95% CI: 4 to 6) and 0.11 percentage points (95% CI: -0.02 to 0.23) absolute risk excess of screening mammography and screen-detected breast cancer in 1 year post-initiation, compared with sulfonylurea initiators, respectively.

Conclusions

Metformin initiators were more likely to receive screening mammograms than sulfonylurea initiators pre- and post-initiation, indicating possible detection bias due to differential screening mammography. Researchers should be aware of the potential for more screening mammograms pre- and post-initiation when interpreting the findings of metformin on breast cancer incidence. Copyright © 2017 John Wiley & Sons, Ltd.

SUBMITTER: Hong JL

PROVIDER: S-EPMC5457352 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Differential Use of Screening Mammography in Older Women Initiating Metformin versus Sulfonylurea.

Hong Jin-Liern JL Henderson Louise M LM Jonsson Funk Michele M Lund Jennifer L JL Buse John B JB Pate Virginia V Stürmer Til T

Pharmacoepidemiology and drug safety 20170329 6

<h4>Purpose</h4>Differential use of screening mammography may lead to biased detection of breast cancer. This study aimed to compare receipt of screening mammography and the incidence of screen-detected breast cancer between metformin and sulfonylurea initiators.<h4>Methods</h4>We used 2006-2014 US Medicare claims to identify initiators of metformin or sulfonylurea aged 65+ years continuously enrolled in Parts A/B for ≥2 years pre-initiation and ≥2 years post-initiation. We reported frequencies ...[more]

PMID: 28370798

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Project description:ImportanceGuidelines recommend individualizing screening mammography decisions for women aged 75 years and older. However, little pragmatic guidance is available to help counsel patients.ObjectiveTo provide an evidence-based approach for individualizing decision-making about screening mammography in older women.Evidence acquisitionWe searched PubMed for English-language studies in peer-reviewed journals published from January 1, 1990, to February 1, 2014, to identify risk factors for late-life breast cancer in women aged 65 years and older and to quantify the benefits and harms of screening mammography for women aged 75 years and older.FindingsAge is the major risk factor for developing and dying from breast cancer. Breast cancer risk factors that reflect hormonal exposures in the distant past, such as age at first birth or age at menarche, are less predictive of late-life breast cancer than factors indicating recent hormonal exposures such as high bone mass or obesity. Randomized trials of the benefits of screening mammography did not include women older than 74 years. Thus it is not known if screening mammography benefits older women. Observational studies favor extending screening mammography to older women who have a life expectancy of more than 10 years. Modeling studies estimate 2 fewer breast cancer deaths/1000 women who in their 70s continue biennial screening for 10 years instead of stopping screening at age 69. Potential harms of continued screening over 10 years include false-positive mammograms in approximately 200/1000 women screened and overdiagnosis (ie, finding breast cancer that would not have clinically surfaced otherwise) in approximately 13/1000 women screened. Providing information about life expectancy along with potential benefits and harms of screening may help older women's decision-making about screening mammography.Conclusions and relevanceFor women with less than a 10-year life expectancy, recommendations to stop screening mammography should emphasize increased potential harms from screening and highlight health promotion measures likely to be beneficial over the short term. For women with a life expectancy of more than 10 years, deciding whether potential benefits of screening outweigh harms becomes a value judgment for patients, requiring a realistic understanding of screening outcomes.

Project description:BackgroundOverdiagnosis is increasingly recognized as a harm of breast cancer screening, particularly for older women.ObjectiveTo estimate overdiagnosis associated with breast cancer screening among older women by age.DesignRetrospective cohort study comparing the cumulative incidence of breast cancer among older women who continued screening in the next interval with those who did not. Analyses used competing risk models, stratified by age.SettingFee-for-service Medicare claims, linked to the SEER (Surveillance, Epidemiology, and End Results) program.PatientsWomen 70 years and older who had been recently screened.MeasurementsBreast cancer diagnoses and breast cancer death for up to 15 years of follow-up.ResultsThis study included 54 635 women. Among women aged 70 to 74 years, the adjusted cumulative incidence of breast cancer was 6.1 cases (95% CI, 5.7 to 6.4) per 100 screened women versus 4.2 cases (CI, 3.5 to 5.0) per 100 unscreened women. An estimated 31% of breast cancer among screened women were potentially overdiagnosed. For women aged 75 to 84 years, cumulative incidence was 4.9 (CI, 4.6 to 5.2) per 100 screened women versus 2.6 (CI, 2.2 to 3.0) per 100 unscreened women, with 47% of cases potentially overdiagnosed. For women aged 85 and older, the cumulative incidence was 2.8 (CI, 2.3 to 3.4) among screened women versus 1.3 (CI, 0.9 to 1.9) among those not, with up to 54% overdiagnosis. We did not see statistically significant reductions in breast cancer-specific death associated with screening.LimitationsThis study was designed to estimate overdiagnosis, limiting our ability to draw conclusions on all benefits and harms of screening. Unmeasured differences in risk for breast cancer and differential competing mortality between screened and unscreened women may confound results. Results were sensitive to model specifications and definition of a screening mammogram.ConclusionContinued breast cancer screening was associated with greater incidence of breast cancer, suggesting overdiagnosis may be common among older women who are diagnosed with breast cancer after screening. Whether harms of overdiagnosis are balanced by benefits and for whom remains an important question.Primary funding sourceNational Cancer Institute.

Project description:ImportanceGuidelines recommend that women 75 years and older should be informed of the benefits and risks of mammography before being screened. However, few are adequately informed.ObjectivesTo develop and evaluate a mammography screening decision aid (DA) for women 75 years and older.DesignWe designed the DA using international standards. Between July 14, 2010, and April 10, 2012, participants completed a pretest survey and read the DA before an appointment with their primary care physician. They completed a posttest survey after their appointment. Medical records were reviewed for follow-up information.Setting and participantsBoston, Massachusetts, academic primary care practice. Eligible women were aged 75 to 89 years, English speaking, had not had a mammogram in 9 months but had been screened within the past 3 years, and did not have a history of dementia or invasive or noninvasive breast cancer. Of 84 women approached, 27 declined to participate, 12 were unable to complete the study for logistical reasons, and 45 participated.InterventionsThe DA includes information on breast cancer risk, life expectancy, competing mortality risks, possible outcomes of screening, and a values clarification exercise.Main outcomes and measuresKnowledge of the benefits and risks of screening, decisional conflict, and screening intentions; documentation in the medical record of a discussion of the risks and benefits of mammography with a primary care physician within 6 months; and the receipt of screening within 15 months. We used the Wilcoxon signed rank test and McNemar test to compare pretest-posttest information.ResultsThe median age of participants was 79 years, 69% (31 of 45) were of non-Hispanic white race/ethnicity, and 60% (27 of 45) had attended at least some college. Comparison of posttest results with pretest results demonstrated 2 findings. First, knowledge of the benefits and risks of screening improved (P < .001). Second, fewer participants intended to be screened (56% [25 of 45] afterward compared with 82% [37 of 45] before, P = .03). Decisional conflict declined but not significantly (P = .10). In the following 6 months, 53% (24 of 45) of participants had a primary care physician note that documented the discussion of the risks and benefits of screening compared with 11% (5 of 45) in the previous 5 years (P < .001). While 84% (36 of 43) had been screened within 2 years of participating, 60% (26 of 43) were screened within 15 months after participating (≥ 2 years since their last mammogram) (P = .01). Overall, 93% (42 of 45) found the DA helpful.Conclusions and relevanceA DA may improve older women's decision making about mammography screening.

Dataset Information

Differential Use of Screening Mammography in Older Women Initiating Metformin versus Sulfonylurea.

Purpose

Methods

Results

Conclusions

Publications

Differential Use of Screening Mammography in Older Women Initiating Metformin versus Sulfonylurea.

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