Jill Stein

February 18, 2011

February 18, 2011 (San Diego, California) — Veterans who are cigarette smokers at the time of elective hip or knee replacement surgery appear to have a significantly increased risk for postoperative complications, according to results of a study reported here at the American Academy of Orthopaedic Surgeons (AAOS) 2011 Annual Meeting.

The study, based on information from a large Veterans Administration (VA) database, showed that current smoking is independently associated with an approximately 50% increase in surgical site infections and pulmonary complications after elective total joint arthroplasty.

"For an elective surgery such as total hip or knee replacement, the preoperative period provides a golden opportunity for quitting smoking," said Jasvinder A. Singh, MD, who is a staff rheumatologist with the Birmingham, Alabama VA Medical Center, and associated professor of medicine at the University of Alabama, Birmingham.

The investigators examined the impact of smoking on 30-day postoperative complications in veterans after elective primary total hip and total knee replacement. The analysis consisted of 33,336 veterans who had their operations between 2002 and 2008 and were part of the VA Surgical Quality Improvement Program (VASQIP).

Smoking Prevalent in Veterans Undergoing Joint Replacement

Cigarette smoking is common in veterans undergoing surgery, Dr. Singh observed. Around 36% of veterans undergoing surgery are current smokers, much higher than the 30% smoking rate for all veterans using VA services and the 23% rate for the general American population.

Currently, roughly 750,000 total hip and total knee arthroplasties are performed yearly in the United States, and the numbers are expected to increase exponentially in the coming years. In fact, by 2030, it is anticipated that there will be a 274% increase in the number of hip replacement procedures and a 673% increase in the number of knee replacement procedures. Importantly, total hip and total knee replacement surgeries are among the most common noncardiac surgical procedures performed in VA facilities, which provide healthcare to 5 million veterans.

The effect of smoking on complications after joint replacement surgery is not clear; this is at least partially due to the small sample size in the various studies to date, he added.

Increased Postoperative Risk Seen in Current Smokers

Results showed that current smokers were significantly more likely than never smokers to have surgical site infections (odds ratio [OR], 1.41; 95% confidence interval [CI], 1.16 to 1.72), pneumonia (OR, 1.53; 95% CI, 1.10 to 2.14), stroke (OR, 2.61; 95% CI, 1.26 to 5.41), and 1-year mortality (OR, 1.63; 95% CI, 1.31 to 2.02).

Former smokers were significantly more likely than nonsmokers to have pneumonia (OR, 1.34; 95% CI, 1.00 to 1.80) and urinary tract infections (OR, 1.26; 95% CI, 1.02 to 1.55).

Dr. Singh said that a strength of the study is the use of state-of the-art VASQIP, databases, from which data were abstracted by trained nurses using validated outcome definitions. The study findings are also bolstered by the large sample size.

He cautioned that it might not be possible to extrapolate the findings to younger patients or women undergoing total joint arthroplasty because most patients in the study were older men.

"Given the elective nature of most total joint arthroplasty procedures, coupled with the significant morbidity and mortality associated with smoking-related complications, a strong case can be made for requiring patients to participate in a preoperative smoking cessation program before undergoing joint replacement surgery," Dr. Singh said. "Smoking cessation programs have the potential to decrease perioperative and postoperative risk and complications."

He also noted that more research is needed to identify which type of smoking cessation program is optimal in these patients.

"While many orthopaedic surgeons like myself had intuitively known that smoking increases the risk of complications after [total knee arthroplasty], including pulmonary complications and surgical site infections, this study provides very strong data to document the link," Michael F. Schafer, MD, chair of the Department of Orthopaedic Surgery at Northwestern University in Chicago, Illinois, and chair of the Communications Cabinet for the AAOS, told Medscape Medical News. "The important message to emerge from this study is that patients considering [total knee arthroplasty] should consider smoking cessation."

"In my spine patients, some of the surgery I do is extremely high risk," he said. "We want to eliminate all of the variables that can possibly complicate surgical outcome, like smoking. So in patients who are not absolutely incapacitated by their problem, I will tell them that I won't do their surgery until they stop smoking."

The study was supported by the VA merit review grant VA IIR IAB 06-038-2 and the use and resources of facilities at the Department of Veterans Affairs Medical Centers at Bedford, Massachusetts; Birmingham, Alabama; and Puget Sound, Washington. Dr. Singh and Dr. Schafer have disclosed no relevant financial relationships.

American Academy of Orthopaedic Surgeons (AAOS) 2011 Annual Meeting. Abstract 473. Presented February 17, 2011.

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