Fitness Matters Even in Bariatric Surgery

ROYAL OAK, Mich., Aug. 8 -- Fitness counts for patients undergoing bariatric surgery, according to researchers here.

Morbidly obese patients with poor cardiorespiratory fitness are more likely to suffer major complications after bariatric surgery, including death, heart attack, and stroke, Peter McCullough, M.D., of William Beaumont Hospital here, and colleagues, reported in the August issue of CHEST.

"Random complications may occur during bariatric surgery," Dr. McCullough said. "However, complications may become more apparent in patients with low levels of cardiopulmonary fitness, because they have little pulmonary reserve and have reduced ability to withstand surgery."

In a prospective study, Dr. McCullough and colleagues divided 108 patients into tertiles based on cardiorespiratory fitness as determined by peak Vo2 levels during exercise testing. Peak V o2 values were:

• First tertile: mean, 13.7 mL/kg/min; median, 14.2 mL/kg/min; range 6.8 to 15.8 mL/kg/min;
• Second tertile: mean, 17.1 mL/kg/min; median, 17.1 mL/kg/min; range, 15.9 to 18.4 mL/kg/min;
• Third tertile: mean, 21.2 mL/kg/min; median, 20.8 mL/kg/min; range, 18.5 to 27.7 mL/kg/min.

The average age of the patients was 46. Eighty-two (75.2%) were women. The average BMI was 48.7 (range 36 to 90). Patients in the first tertile were more likely to be female, older, and nonwhite, and had a higher BMI, and had diabetes and hypertension. Rates of coronary artery disease, pulmonary diseases, and arthritis were similar among the tertiles of peak Vo2. Of note, six of 37 patients (16.2%) in the first tertile were cigarette smokers, compared with three of 72 patients (4.2%) of the second and third tertiles combined (P< 0.07).

After laparoscopic Roux-en-Y gastric bypass surgery, patient outcomes were classified as intermediate (operative and reversible), primary (permanent or potential organ damage), and secondary (length of stay and readmission).

Operative times were longer by 24.8 minutes for the first tertile compared with the third tertile (P=0.04). Hospital length of stay and 30-day readmission rates (assessed in all patients) were highest in the lowest tertile of peak Vo2: 3.8 days, vsersus2.8 days for all others (P<0.002).

Overall, Dr. McCullough and colleagues found, patients in the first tertile were nearly six times as likely to suffer primary complications -- death, unstable angina, myocardial infarction, venous thromboembolism, renal failure, or stroke -- than those in the other tertiles combined.

Specifically, six of the 37 patients (16.6 %) in the first tertile suffered one or more of the primary complications, compared with only two of the 72 patients in the other two tertiles (2.8%). The difference was statistically significant at P=0.02.

Multivariate analysis found the first tertile of peak Vo2 had an OR of 12.89 (versus all others) [95% CI, 1.14 to 146.21; P<0.04] and male gender had an OR of 10.65 (95% CI, 1.91 to 59.21; P<0.007) for the prediction of postoperative complications.

When peak Vo2 was used as a continuous variable for every unit decrease in VO₂, the risk of complications increased by 61%. The odds ratio per unit decrease was 1.61, with a 95% confidence interval from 1.19 to 2.18; the result was significant at P=0.002.

At a cut point of 15.8 mL/kg/min (upper boundary for first tertile) for peak Vo2, there was a sensitivity of 75.0% and a specificity of 73.3%. Conversely, a cut point of 18.5 mL/kg/min (lower boundary of third tertile) had 87.5% sensitivity and 34.7% specificity for the composite outcome of postoperative complications.

"The benefits of bariatric surgery clearly outweigh the risks." Dr. McCullough said. "Morbid obesity is associated with numerous health risks, including cardiovascular disease, respiratory conditions, diabetes, sleep apnea, and an increased rate of death (and) bariatric surgery has been shown to reduce comorbidities and long-term mortality in morbidly obese patients."

That said, he and colleagues concluded that physicians should measure cardiopulmonary fitness before operating. They were not yet ready to recommend postponing surgery to improve fitness.

"A randomized trial in those with low peak Vo2 designed to augment this measure of cardiorespiratory fitness, versus usual care, would be needed to conclude that selected patients should undergo preoperative weight loss and exercise training to reduce complications with bariatric surgery," they wrote. "In the meantime, the present findings suggest that it would be prudent to directly measure peak Vo2 and provide this prognostic information to the patient and the surgical team."

The finding reinforces the need for physicians to teach patients about the dangers of obesity, commented W. Michael Alberts, M.D., who is president of the American College of Chest Physicians, which publishes CHEST.

"Physicians and other health-care providers should educate obese patients on current options for healthy and permanent weight loss in order to minimize long-term health complications," Dr. Alberts said.

The authors noted that the greatest limitation to this analysis was the small sample size, with a total of eight composite and 16 individual primary outcome events.