The researchers looked at the choices made by 1,720 patients with hip osteorarthritis and 7,727 patients with knee osteoarthritis. In the hip group, 820 patients were given the tools while the rest were given traditional care. In the knee group, 3,510 patients were given the decision tools, while 4,217 were given traditional care.
The patients were seen in an outpatient clinic during 18 months starting in January 2009 for the intervention group and during 18 months starting in January 2007 for the control group. Surgery rates were compared with rates of non Group Health patients in that region for each time period.
The fact that surgery trends were compared with those of the non Group Health patient community made it unlikely that the economic recession—which influenced fewer surgeries or cost savings—was responsible for the trend.
"We examined trends in hip and knee replacement in our region of Washington State (outside of Group Health) and found that the rates of hip and knee surgery were increasing or flat during the study period, not decreasing like we saw in our study," Arterburn says. "So that makes it much less likely that the economy was driving the change we saw in our system."