Studies show growth in the use of decision aids has been dramatic. According to researchers at the Ottawa Health Research Institute, hundreds are in use today, helping patients make informed decisions about everything from heart surgery to cancer care, and hundreds more are in development. At Group Health alone, more than 25,000 patients have received decision aids in six specialties.

Group Health began distributing decision aids to patients for two reasons. One was legal. In 2007, Washington State passed legislation recognizing the use of decision aids and shared decision making as a higher standard of informed consent. In shared decision making, providers and patients work together to make informed treatment decisions – something Dr. Arterburn emphasizes is a vital part of the process.

"It's not just the patient or provider making the choice; it really is a shared decision," he says.

Decision aids were also part of an overall quality-improvement program that included giving patients more say in decisions about elective surgery and reducing what were deemed "unwarranted variations in care." Ideally, treatment should reflect patients' values and preferences. More often, it reflects providers' preferences, as documented by extensive studies – including analyses done by the Dartmouth Atlas Project, an organization dedicated to documenting variations in how medical resources are distributed and used in the U.S.

This means care can vary widely from one geographical area to another, as Group Health found within its own organization. "The assumption is that patients in Tacoma are not that different from those in Bellevue or Seattle, so in terms of OA, we couldn't explain the large variations in care, which seem to be driven by local provider practices and expertise, not by age, sex, or severity of disease.,” says Dr. Arterburn.

"It's tough for providers who have training and expertise in a certain area not to represent the benefits more than the risks,” he explains. “We know from studies of patients who have faced different treatment decisions that they often don't have key pieces of information, such as how likely they are to need another replacement on the same knee in 15 years, how long the recovery period is or what the risks are, such as infection."

By providing that information, in a balanced, understandable way, decision aids aim to improve the quality of care and empower patients.

"Patients deserve to have all available information [on outcome probabilities] so they can then reflect on what is important to them," Dr. Arterburn says. "Decision aids never indicate there is one right choice. The right choice is the one that is right for you."

In the two years since she chose to forego surgery Howell lost 56 pounds. Her knee rarely bothers her; losing weight has relieved much of the pressure on the joint. "My feeling was that if I could keep my original equipment as long as possible, that would be a good idea," she says.

But not everyone is convinced decision aids always benefit the patient. Amanda E. Nelson, MD, an assistant professor of medicine in the Thurston Arthritis Research Center at the University of North Carolina at Chapel Hill, says that decision aids might result in fewer or delayed procedures for appropriate patients. But she says, they "might also have the potential to delay a needed procedure in a patient who should not wait."

She adds, "Further study is needed to understand the initial impact of such decision aids, the reasons for providers’ decisions to provide it or not, and the long-term impact of this type of intervention on rates of surgery and whether that impact [higher or lower surgery rates] is actually beneficial to patients over time."