Percent Body Fat Predicts Surgical Infections : Patients with percent body fat greater than 37% were two times more likely to develop an SSI.

MIAMI BEACH — Preoperative percent body fat is an independent predictor of surgical site infection risk and is a more accurate way to define obesity than is body mass index, according to preliminary results of a prospective, ongoing trial.

Surgical site infections (SSIs) develop in an estimated 290,000 of the 27 million procedures performed annually in the United States, data from the Centers for Disease Control and Prevention indicate. Previous research has linked obesity—as well as type of procedure, patient comorbidity, immunosuppression, and cigarette smoking—to an increased risk of such infections (Dis. Colon Rectum 2007;50:2223-37; J. Cardiovasc. Surg. 2007;48:641-6).

In the initial cohort of 194 patients in this study, Harvard medical student Emily Waisbren and her associates in the departments of anesthesiology and surgery at Brigham and Women's Hospital in Boston measured percent body fat using bioelectrical impedance analysis and body mass index (BMI) using the standard height and weight formula.

Patients ranged in age from 18 years to 64 years (mean age, 49), and 66% were women. The mean BMI was 29.5 kg/m

A total of 130 patients (67%) were obese according to the body fat criterion, compared with 74 (38%) using the BMI definition.

Participants were assessed before, during, and 30 days after elective surgery (primarily general, orthopedic, and obstetric procedures) on the basis of medical records, questionnaires, and follow-up telephone interviews. A total of 31% of the patients were taking antihypertensive medication, and 18% were current smokers. Most patients had an American Society of Anesthesiologists (ASA) score of 2, “so they were relatively healthy,” Ms. Waisbren said.

SSIs developed in 27 patients (14%). According to the percent body fat cutoffs, infections occurred in 4.7% of nonobese patients and in 18.5% of obese patients. In contrast, when the BMI cutoff was used, 14.2% of the nonobese and 13.5% of obese patients developed SSIs.

As percent body fat increased, there was a statistically significant increase in SSIs. For example, patients with percent body fat greater than 37% were two times more likely to develop an SSI, Ms. Waisbren said. “An association with increased SSI risk was seen with BMI also, but it was not statistically significant.”

Although there were no deaths related to these infections, Ms. Waisbren said that patients with an SSI experienced more adverse outcomes, including wound dehiscence, seroma, and hematoma, than did those without infections.

A meeting attendee asked if patients were possibly overlabeled as obese because two-thirds met the percent body fat definition. “There have been very little data to define the cutoff point,” Ms. Waisbren said. “But you raise the point of how appropriate the American Council on Exercise definition is.”

When a meeting attendee asked why the hip-to-waist ratio was not assessed, Ms. Waisbren said the investigators believed BMI was more accurate than hip-to-waist ratio.

However, she said, “BMI misses an important difference in body composition.” For example, a male body builder and an overweight woman with the same height and weight would have the same BMI, but very different body fat percentages.

Percent body fat was an independent predictor of SSI, according to a univariate analysis. Pedal edema, recent surgery, higher National Nosocomial Infection Surveillance score, and class 2 (clean-contaminated) or higher wound ratings were other predictors.

A multivariate assessment is planned as part of the ongoing study, Ms. Waisbren said.

This study was awarded the best research abstract at the meeting. Data collected for a total of 436 patients in this ongoing study concur with the initial cohort findings, Ms. Waisbren said.

She added that the plan is to enroll 600 elective surgery patients in the final assessment.

MIAMI BEACH — Preoperative percent body fat is an independent predictor of surgical site infection risk and is a more accurate way to define obesity than is body mass index, according to preliminary results of a prospective, ongoing trial.

Surgical site infections (SSIs) develop in an estimated 290,000 of the 27 million procedures performed annually in the United States, data from the Centers for Disease Control and Prevention indicate. Previous research has linked obesity—as well as type of procedure, patient comorbidity, immunosuppression, and cigarette smoking—to an increased risk of such infections (Dis. Colon Rectum 2007;50:2223-37; J. Cardiovasc. Surg. 2007;48:641-6).

In the initial cohort of 194 patients in this study, Harvard medical student Emily Waisbren and her associates in the departments of anesthesiology and surgery at Brigham and Women's Hospital in Boston measured percent body fat using bioelectrical impedance analysis and body mass index (BMI) using the standard height and weight formula.

Patients ranged in age from 18 years to 64 years (mean age, 49), and 66% were women. The mean BMI was 29.5 kg/m

A total of 130 patients (67%) were obese according to the body fat criterion, compared with 74 (38%) using the BMI definition.

Participants were assessed before, during, and 30 days after elective surgery (primarily general, orthopedic, and obstetric procedures) on the basis of medical records, questionnaires, and follow-up telephone interviews. A total of 31% of the patients were taking antihypertensive medication, and 18% were current smokers. Most patients had an American Society of Anesthesiologists (ASA) score of 2, “so they were relatively healthy,” Ms. Waisbren said.

SSIs developed in 27 patients (14%). According to the percent body fat cutoffs, infections occurred in 4.7% of nonobese patients and in 18.5% of obese patients. In contrast, when the BMI cutoff was used, 14.2% of the nonobese and 13.5% of obese patients developed SSIs.

As percent body fat increased, there was a statistically significant increase in SSIs. For example, patients with percent body fat greater than 37% were two times more likely to develop an SSI, Ms. Waisbren said. “An association with increased SSI risk was seen with BMI also, but it was not statistically significant.”

Although there were no deaths related to these infections, Ms. Waisbren said that patients with an SSI experienced more adverse outcomes, including wound dehiscence, seroma, and hematoma, than did those without infections.

A meeting attendee asked if patients were possibly overlabeled as obese because two-thirds met the percent body fat definition. “There have been very little data to define the cutoff point,” Ms. Waisbren said. “But you raise the point of how appropriate the American Council on Exercise definition is.”

When a meeting attendee asked why the hip-to-waist ratio was not assessed, Ms. Waisbren said the investigators believed BMI was more accurate than hip-to-waist ratio.

However, she said, “BMI misses an important difference in body composition.” For example, a male body builder and an overweight woman with the same height and weight would have the same BMI, but very different body fat percentages.

Percent body fat was an independent predictor of SSI, according to a univariate analysis. Pedal edema, recent surgery, higher National Nosocomial Infection Surveillance score, and class 2 (clean-contaminated) or higher wound ratings were other predictors.

A multivariate assessment is planned as part of the ongoing study, Ms. Waisbren said.

This study was awarded the best research abstract at the meeting. Data collected for a total of 436 patients in this ongoing study concur with the initial cohort findings, Ms. Waisbren said.

She added that the plan is to enroll 600 elective surgery patients in the final assessment.

MIAMI BEACH — Preoperative percent body fat is an independent predictor of surgical site infection risk and is a more accurate way to define obesity than is body mass index, according to preliminary results of a prospective, ongoing trial.

Surgical site infections (SSIs) develop in an estimated 290,000 of the 27 million procedures performed annually in the United States, data from the Centers for Disease Control and Prevention indicate. Previous research has linked obesity—as well as type of procedure, patient comorbidity, immunosuppression, and cigarette smoking—to an increased risk of such infections (Dis. Colon Rectum 2007;50:2223-37; J. Cardiovasc. Surg. 2007;48:641-6).

In the initial cohort of 194 patients in this study, Harvard medical student Emily Waisbren and her associates in the departments of anesthesiology and surgery at Brigham and Women's Hospital in Boston measured percent body fat using bioelectrical impedance analysis and body mass index (BMI) using the standard height and weight formula.

Patients ranged in age from 18 years to 64 years (mean age, 49), and 66% were women. The mean BMI was 29.5 kg/m

A total of 130 patients (67%) were obese according to the body fat criterion, compared with 74 (38%) using the BMI definition.

Participants were assessed before, during, and 30 days after elective surgery (primarily general, orthopedic, and obstetric procedures) on the basis of medical records, questionnaires, and follow-up telephone interviews. A total of 31% of the patients were taking antihypertensive medication, and 18% were current smokers. Most patients had an American Society of Anesthesiologists (ASA) score of 2, “so they were relatively healthy,” Ms. Waisbren said.

SSIs developed in 27 patients (14%). According to the percent body fat cutoffs, infections occurred in 4.7% of nonobese patients and in 18.5% of obese patients. In contrast, when the BMI cutoff was used, 14.2% of the nonobese and 13.5% of obese patients developed SSIs.

As percent body fat increased, there was a statistically significant increase in SSIs. For example, patients with percent body fat greater than 37% were two times more likely to develop an SSI, Ms. Waisbren said. “An association with increased SSI risk was seen with BMI also, but it was not statistically significant.”

Although there were no deaths related to these infections, Ms. Waisbren said that patients with an SSI experienced more adverse outcomes, including wound dehiscence, seroma, and hematoma, than did those without infections.

A meeting attendee asked if patients were possibly overlabeled as obese because two-thirds met the percent body fat definition. “There have been very little data to define the cutoff point,” Ms. Waisbren said. “But you raise the point of how appropriate the American Council on Exercise definition is.”

When a meeting attendee asked why the hip-to-waist ratio was not assessed, Ms. Waisbren said the investigators believed BMI was more accurate than hip-to-waist ratio.

However, she said, “BMI misses an important difference in body composition.” For example, a male body builder and an overweight woman with the same height and weight would have the same BMI, but very different body fat percentages.

Percent body fat was an independent predictor of SSI, according to a univariate analysis. Pedal edema, recent surgery, higher National Nosocomial Infection Surveillance score, and class 2 (clean-contaminated) or higher wound ratings were other predictors.

A multivariate assessment is planned as part of the ongoing study, Ms. Waisbren said.

This study was awarded the best research abstract at the meeting. Data collected for a total of 436 patients in this ongoing study concur with the initial cohort findings, Ms. Waisbren said.

She added that the plan is to enroll 600 elective surgery patients in the final assessment.