"While some prior studies have documented socioeconomic disparities in the outcomes of individual procedures, ours is the first to show that the relationship is consistent across a wide range of surgical procedures," said lead study author Nancy Birkmeyer, Ph.D.
Birkmeyer, an associate professor of surgery at the University of Michigan, and colleagues used census and Medicare data to evaluate postoperative death rates in more than 1 million elderly patients. All patients had undergone one of six common, high-risk surgical procedures between 1999 and 2003.
The study appears in the September issue of the journal Medical Care.
For all of the surgical procedures — heart or cancer surgery — socioeconomic status significantly influenced the patient's risk of death. Odds of dying were between 17 percent and 39 percent higher for patients with low socioeconomic status, the authors found.
"Patients that live in socioeconomically disadvantaged areas have higher surgical mortality rates compared to patients that live in areas with higher socioeconomic status. This is mainly because the quality of care is lower at hospitals where patients of lower socioeconomic status tend to be treated," Birkmeyer said.
In fact, all patients — regardless of income — who underwent treatment at the hospitals in the poorest areas were more likely to die, whereas all patients undergoing surgery in the wealthiest ZIP codes proved less likely to die.
"It may be that hospitals that treat patients of lower socioeconomic status have lower quality of care due to fewer resources, such as technologically advanced equipment or specialists," Birkmeyer said.
Harlan Krumholz, M.D., A professor of medicine, epidemiology and public health at Yale University, called the study a first step in understanding the patterns of care, but said that the findings do not provide concrete answers for elderly patients needing surgery.
"The study can only really raise questions about inequalities in outcomes, because the authors have limitations in their ability to know the socioeconomic status of any particular patient and the condition of the patient when they had the surgery," Krumholz said. "Nevertheless, it is time for us to look closely at whether people are getting the same care and outcomes regardless of their financial circumstances."