Another reason not to smoke

Veterans undergoing elective joint replacement surgery who currently smoke are at risk for short-term complications, according to study data presented Thursday.

Although smoking has been linked to complications following many surgical procedures, the effect of smoking on veterans’ outcomes following elective total hip arthroplasty (THA) or total knee arthroplasty (TKA) has not been previously studied.

Led by Jasvinder Singh, MD, researchers at the University of Alabama retrospectively reviewed 33,294 patients (mean age: 64 years; 95 percent male; 66 percent Caucasian) who had undergone elective primary THA or TKA between 2002 and 2008 in Veterans Administration facilities and had been assessed in the National Surgical Quality Improvement Program.

The researchers divided patients into three groups: current smokers (n = 7,984); prior smokers (n = 6,297); and never smokers (n = 19,013). Never smokers were defined as patients who did not smoke in the year prior to surgery and who had zero or missing pack years (the number of packs smoked per day multiplied by the number of years the patient smoked).

Outcomes for each of the three groups were compared for incidences of surgical-site infections (SSI), vascular complications, pneumonia and other pulmonary complications, renal failure, venous thromboembolism (VTE), and urinary tract infection (UTI) at 30 days after surgery. Mortality was assessed at 30 days, 90 days, and 1 year after surgery. Because prior smokers tended to be sicker than the other groups, the researchers used multivariate logistic regression to assess adjusted risk of the outcome comparisons.

Smoking status predicts complications
The researchers found that the odds of SSIs were 41 percent higher in current smokers, compared to patients who had never smoked. “This is an important observation,” they wrote, “since SSIs account for 38 percent of all infections in surgical patients, and are associated with longer hospital stays.”

Current smokers also had significantly higher odds of pneumonia (53 percent), stroke (161 percent), and 1-year mortality (63 percent), compared to never smokers.

Similarly, prior smokers had higher odds of pneumonia (34 percent) and stroke (114 percent), compared with never smokers. Prior smokers also had higher odds of UTIs (26 percent) and pulmonary complications (30 percent), compared to patients who had never smoked.

The rates of VTE, myocardial infarction, renal failure, exturbation, and reintubation did not differ significantly by smoking status.

The authors noted that because the majority of their study patients were older men, findings of the study may not be generalized to women and younger arthroplasty patients. Another limitation was the accuracy of the smoking data.

Despite the limitations, “our findings of higher rates of morbidity and mortality in current smokers, compared to non-smokers, indicate that a preoperative smoking cessation program needs to be seriously considered in patients undergoing elective THA/TKA procedures,” said Dr. Singh.

Dr. Singh’s coauthors of “Is Smoking a Risk Factor for Complications After Elective Primary Total Knee/Hip Arthroplasty?” include Thomas Houston, MD; Brent A. Ponce, MD; Grady Maddox, MD; Michael J. Bishop, Joshua Richman, Elizabeth Campagnna, MS; William G. Henderson, PhD; and Mary Hawn, MD, FACS.

Disclosure information: Dr. Singh—Savient, URL pharma, EuroRSG, Novartis, Takeda; Dr. Ponce—Arthrex, Inc., Tornier; Mr. Bishop—Eli Lilly, GlaxoSmithKline, Pfizer, Merck; Drs. Houston, Maddox, Henderson, Hawn, Mr. Richman, and Ms. Campagnna—no conflicts.

Prepared by Maureen Leahy, assistant managing editor for AAOS Now.