Until the 1980s, workplace health clinics generally existed to treat people who were injured on the job. Although that is still a key function, many employers are expanding the clinics' role to include primary healthcare services. In 2010, 15% of employers with 500 or more employees had clinics providing primary-care services, according to the consulting firm Mercer. An additional 10% said they were considering doing so this year or next. Employer interest in on-site primary care is motivated by several factors, say experts. By making it easy for employees to get a mammogram or check their blood pressure, companies hope to avert expensive medical problems down the road. In addition, employers hope that by ensuring that their clinic staff follows evidence-based guidelines for care, their workers will receive treatment that's appropriate to their medical needs, says Ha Tu, a senior health researcher at the Center for Studying Health System Change. This would likely lead to fewer referrals to specialists, for example, and pricey imaging tests.