Author: Michael Vlessides
Surgical procedures done in the outpatient setting have long been touted as a cost-effective alternative to their inpatient counterparts. Now, analyses of two databases have found that certain outpatient surgeries may actually be safer, too.
In a pair of presentation s at the 2019 annual meeting of the International Anesthesia Research Society, Girish P. Joshi, MD, and Eric Rosero, MD, reported that both laparoscopic cholecystectomy and hysterectomy performed in the outpatient setting resulted in lower rates of postoperative complications and 30-day readmission than their inpatient counterparts. The next challenge, the researchers said, is determining why these differences exist.
Laparoscopic Cholecystectomy and Hysterectomy
“Laparoscopic cholecystectomy is one of the most common general surgical procedures,” said Dr. Rosero, an assistant professor of anesthesiology and pain management at UT Southwestern Medical Center, in Dallas. “Over the last decade or so, it’s been moving more and more to the outpatient setting. In fact, it’s estimated that more than half of all laparoscopic cholecystectomies are now done on an outpatient basis.
“Yet, despite this increasing popularity, both surgeons and anesthesiologists alike think that inpatient settings are safer environments for patients having surgery, but nobody has proven that.”
The investigators extracted data from the 2014 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database. The study population consisted of adult patients undergoing elective laparoscopic cholecystectomy. Patients who had a diagnosis of acute cholecystitis were excluded from the study.
Propensity matching was used to indicate the probability of the procedure occurring in the inpatient or outpatient setting; this analysis used a logistic regression model to control for patient age, ASA physical status class, comorbidities, functional status, smoking status, procedure type (with or without intraoperative cholangiogram or bile duct exploration), preoperative hematocrit level and preoperative creatinine as predictors. The propensity scores were then used to assemble a matched cohort of patients (1:1) undergoing inpatient or outpatient laparoscopic cholecystectomy.
The study’s primary outcomes were 30-day readmission and a composite of 30-day postoperative complications, which included respiratory failure, pneumonia, myocardial infarction, pulmonary embolism, acute renal failure, hemorrhage, stroke, surgical site infection or sepsis.
As Drs. Rosero and Joshi reported (abstract D13), a total of 23,971 laparoscopic cholecystectomy procedures were identified, including 19,206 outpatient (80.1%) and 4,765 inpatient (19.9%). Perhaps not surprisingly, inpatients were older and had a higher incidence of chronic comorbidities, greater mean body mass index and higher ASA class. After propensity matching, there were 4,034 patients in each setting.
Results showed that 4.36% of inpatients experienced postoperative complications, a significantly higher rate than the 1.39% among outpatients (P<0.001). Similarly, 30-day readmission was significantly more frequent in inpatients, at 4.91%, than in outpatients, 3.10% (P<0.0001).
Role of Post-op Infections
Mixed regression analyses confirmed that the odds of postoperative complications (odds ratio [OR], 3.24; 95% CI, 2.39-4.39; P<0.0001) and 30-day readmission (OR, 1.62; 95% CI, 1.28-2.03; P<0.0001) were significantly greater in the inpatient group.
“So, the odds of any complication were three times higher when the patient was in the inpatient setting compared to the outpatient,” Dr. Rosero said in an interview with Anesthesiology News. “And the rate of readmissions was some 60% higher when it was inpatient versus outpatient, even after controlling for all the patient factors.
“It was definitely unexpected to see that the inpatient setting is less safe than the outpatient setting,” Dr. Rosero said. “Most clinicians think that outpatients are at higher risk of coming back to the hospital or having unexpected complications because their time in the hospital is so short. But it was the opposite, actually.”
The risk for postoperative complications was largely driven by rates of postoperative infections. “We assume this is because if patients stay longer in the hospital, they have a higher risk of acquiring an infection from the other patients,” Dr. Rosero said.
The researchers conducted a similar analysis using the NSQIP database, this time looking at women undergoing inpatient and outpatient laparoscopic hysterectomy (abstract E17). They excluded nonelective cases and those with cancer diagnoses. Once again, propensity scores matched inpatient and outpatient cases at a 1:1 ratio.
There were 19,025 laparoscopic hysterectomy cases, of which 14,959 were inpatients (71.6%) and 4,066 were outpatients (21.4%). The matching algorithm produced 2,491 patients per group.
The analysis found superior outcomes in the outpatient setting over the inpatient one. The overall incidence of postoperative complications was 3.73% among inpatients and 1.77% among outpatients (OR, 2.157; 95% CI, 1.50-3.10; P<0.0001).
Similarly, 30-day readmission was significantly more frequent for inpatients, at 2.05%, than for outpatients, at 1.24% (OR, 1.66; 95% CI, 1.06-2.60; P=0.0275).
Confounding Factors Not Accounted For
Even though the researchers were encouraged that their findings demonstrate the relative safety of inpatient laparoscopic cholecystectomy and hysterectomy, they were quick to note that the database does not account for such potential confounding factors as patient socioeconomic status, behavioral factors, and factors specific to the surgical facility.
“But it’s a starting point to think that these outpatient procedures are definitely safe and may be safer than inpatient,” Dr. Rosero said.
Dr. Joshi, who is a professor of anesthesiology and pain medicine also at UT Southwestern Medical Center, agreed. “For years, we’ve talked about the benefits of ambulatory surgery, but most of the time those benefits were cost-related, not necessarily outcomes-related. This is the first time we have shown that the outcomes are also significantly better in the ambulatory setting.”
As Dr. Joshi explained, a key part of the research is the examination of procedure-specific outcomes. “The problem occurs when we put all the data together, which doesn’t allow us to see the nitty-gritty of each procedure. Because if we want to tease out why there’s a difference between the two settings, we really need to have procedure-specific data.”
Although Kumar G. Belani, MBBS, recognized the shortcomings of database analyses, he was comfortable with the idea that some patients can undergo laparoscopic cholecystectomy or hysterectomy on an ambulatory basis, after a thorough preoperative analysis.
“It will be interesting to know the intraoperative times between the matched groups,” commented Dr. Belani, a professor of anesthesiology at the University of Minnesota, in Minneapolis. “I have a feeling that they would be much shorter in the ambulatory group, and less time spent in the operating room is always better from an outcomes point of view.
“However, I do not want individuals to go away with the feeling that the inpatient setting is less safe,” Dr. Belani added. “It will take a prospective, randomized controlled study to do a proper comparison. Ambulatory centers are now well equipped and staffed by expert teams, and surgeons need to take advantage of caring for eligible patients on an ambulatory basis.”