Photo credit: <a href="http://www.freedigitalphotos.net/images/view_photog.php?photogid=2664">Stuart Miles</a>

The top challenge facing two thirds of companies endeavoring to reduce medical costs is promoting behavioral changes that lead to improved health and on-the-job performance of their employees, according to a new study.

Aon Hewett, a unit of Aon Corp., Lake Forest, Ill., reported this finding in its “2012 Health Care Survey: Better Health. Better Results.” The study examines 1,800 employers—organizations representing approximately 15 million employees and an estimated $120 billion in annual health care spending—to discern trends in respect to the companies’ current and future health care practices.

Sixty-five percent of the surveyed companies say that motivating employee participants to adopt measures that reduce health risk factors is their top challenge. Smaller percentages of the surveyed companies cite other factors as top challenges.

Among them: government compliance and regulations (35%), managing the health of an aging workforce (30%), culture shift and reluctance to change (29%) and understanding employee attitudes toward health and wellness (28%).

Seven in 10 of the employers flag “increase utilization of wellness and prevention” as a desired outcome. Solid majorities of the companies also cite as a desired outcome “increasing participants’ awareness of, and decision making related to, health issues” (62%), “lower health risk of the employee population” (58%), and “increase participation in health improvement and disease management (55%).

Noted as a desired outcome by 42% of employers is “increase participant accountability for consumer behaviors regarding use of the health care system.”

More than six in 10 (61%) of employers offer incentives or disincentives to motivate sustained health care behavior change, the report states. Nearly half of the respondents promote a culture of health in the workplace (48%), or implement a company-wide (or global) wellness policy and guiding principals (48%).

Just over four in 10 respondents, the survey notes, are moving to reward improved health results or outcomes (44%). And nearly a third (31%) are promoting other consumer-driven strategies.