Factors associated with increased risk of in-hospital falls after total hip or knee replacement surgery

Investigators from Hospital for Special Surgery have identified factors that are associated with an increased risk of in-hospital falls after total hip or knee replacement surgery. The study, which appears online ahead of print in the Journal of Arthroplasty, may help hospitals design interventions to reduce falls in at-risk populations. Risk factors identified from a national database of patients included undergoing a joint replacement revision surgery and a number of comorbid conditions, such as congestive heart failure.

"This study helps doctors know which patients to look out for," said Stavros Memtsoudis, M.D., Ph.D., an anesthesiologist at Hospital for Special Surgery (HSS), who led the study. "Some studies have shown that falls occur when patients get up from their bed to go to the bathroom. While it may be unreasonable to put a helper into every room to help patients go to the bathroom, it would certainly be feasible to identify a smaller group of patients at-risk and focus efforts on them."

"Our study is one of the first to look into patients that suffer falls during their hospital stay after undergoing total hip or knee replacement surgery," said Alejandro Gonzalez Della Valle, M.D., an orthopedic surgeon at Special Surgery who was also involved in the study. "We detected an alarming increase in the national prevalence of this potentially preventable problem and identified a number of patient factors that were associated with an increased risk of falling during a hospital stay. The information in our study can be used by health care professionals to design or perfect in-hospital fall prevention programs."

In-hospital falls increase morbidity, prolong hospitalizations, increase health care costs, and sometimes spur lawsuits against hospitals. They can cause wound complications and assorted medical problems that aren't related to the primary procedure, including concussions. According to published data, in-hospital falls occur in 2% to 17% of patients during short-term hospitalization. While orthopedic surgeries can put patients at risk for in-hospital falls, only two published studies to date have evaluated the risk for these types of falls in orthopedic patients.

"In-hospital falls are a big problem that hasn't been studied very well. They represent a problem not only for the patient, but for the surgeon as well—if the wound bursts open during a fall, patients may require revision surgery or may develop early wound infections," said Dr. Memtsoudis. "For patients, it prolongs hospital stays, increases costs, and can put a big damper on recovery in general."

To study these falls in patients undergoing orthopedic procedures in greater depth, HSS researchers turned to the Nationwide Inpatient Sample, sponsored by the Agency for Healthcare Research and Quality (AHRQ). This is the largest inpatient database available in the United States that includes information on patients of all ages. It collects data from about 20% of all hospitalizations in the U.S. This large cohort of patient information is unparalleled and allows for the appropriate study of relatively rare events surrounding surgery.

The investigators analyzed data between 1998 and 2007 to identify patients who had undergone a total hip or knee replacement. Using statistical modeling, they then compared characteristics of patients who had suffered in-hospital falls to those who had not suffered a fall. During the study period, the rate of patients that fell during their in hospital recovery was 0.85%.

Patients were more likely to fall if they were male, older, belonged to a minority race, or were undergoing a revision joint replacement surgery. Patients were also at heightened risk if they had certain comorbid conditions, including congestive heart failure, a clotting or bleeding disorder, liver disease, neurologic disease, electrolyte/fluid abnormalities, and recent weight loss. Pulmonary circulatory disease posed the greatest risk. Obesity, hypothyroidism, uncomplicated diabetes and cancer were not associated with an increased risk of falling. Postoperative complications including deep vein thrombosis, adult respiratory distress syndrome and pulmonary embolism were also associated with higher fall rates, although it remains unclear if they were the reason or the consequence for this event.

In line with other studies, patients who experienced falls had longer hospital stays and were more frequently discharged to other health care facilities, instead of their primary residence.

The researchers hope that clinicians and researchers use the information gleaned from this study to design strategies to reduce the incidence of in-hospital falls—doctors now have a smaller target to focus on to make a difference. "If a patient comes in for revision surgery or has certain comorbidities, we know they are at increased risk," Dr. Memtsoudis explained. "Thus patients with these characteristics could be tagged and awareness of staff to especially watch out for this population could be raised."

An additional interesting study finding was that the rate of falls is increasing. "The incidence over time jumped from 0.4 percent to 1.3 percent within a ten year time period, which means that this problem is becoming bigger," said Dr. Memtsoudis. "It could be because of more reporting, because it is mandatory to report these falls, or because the patient population that we see—and we have more and more evidence for this—is actually getting sicker, and so may therefore be at a greater risk."

This study was a multidisciplinary effort involving anesthesiology, orthopedics and members of the department of biostatistics.