The largest study to date of the effect of having high-deductibles in health plans show that while health spending lessens, so is preventive efforts such as immunizations, mammograms, cervical and colorectal cancer screenings, despite waiving fees for preventive health care. "High-deductible and consumer-directed health plans have been gaining favor as one way to help control health care costs. By 2009, about 20% of Americans with employer-sponsored health coverage were enrolled in such plans.