Even a small copayment can significantly lower mam-mography rates among women age 65 to 69, Amal N. Trivedi, MD, MPH, of Brown University and colleagues reported in the New England Journal of Medicine (358:375-383, 2008).
The authors concluded that elderly adults should be exempted from cost sharing for mammography and other effective preventive services.
Although cost sharing through deductibles and copayments "may result in more prudent use of medical care and avoidance of low-value services," the investigators wrote, it may also reduce the use of appropriate medical care.
The researchers reviewed coverage for mammography within 174 Medicare managed care plans from 2001 through 2004. Among 550,082 individual observations for 366,475 women, age 65 to 69, they compared the rate of biennial breast cancer screening in plans requiring cost sharing for mammography with the rate in plans with full coverage.
They found that the number of plans requiring cost sharing for mammography, defined as a copay of more than $10 or coinsurance of more than 10%, increased during the study period: from 3 in 2001 (representing 0.5% of women) to 21 in 2004 (11.4% of women). The copays ranged from $12.50 to $35.00 (median $20.00). African-American women and those living in areas with lower income and educational levels were more likely to enroll in cost sharing plans.
Biennial mammography screening rates were 77.5% in the full coverage plans vs 69.2% in the cost sharing plans. This 8.3% difference persisted in multivariate analyses (7.2%, P < .001).
"This effect was greater in magnitude than that of all other covariates in the model," Dr. Trivedi wrote.