PCNL Outcomes Not Worse in the Obese

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Complication rates and costs associated with the procedure did not vary by BMI, data show.

Obese patients are at no greater risk of failure or complications after undergoing percutaneous nephrostolithotomy (PCNL) than non-obese individuals, a study found.

The study, which involved 150 patients who underwent PCNL at the University of Texas Southwestern Medical Center at Dallas, also found that obese patients were not more likely to have stones following PCNL or to accrue high direct costs, investigators reported in Urology (2008; published online ahead of print).

Previous studies have suggested that obesity does not adversely affect outcomes of PCNL, but some researchers and clinicians remained skeptical because obesity has been shown to negatively impact outcomes from such other procedures as partial nephrectomy.

In the new study, Yair Lotan, MD, and colleagues divided patients into four categories based on BMI: normal weight (less than 25 kg/m2), overweight (BMI 25-30 kg/m2), obese (BMI 30-40), and morbidly obese (BMI 40 or higher). Fifty-five percent of subjects were women, and 53% were obese or morbidly obese.

The groups did not vary significantly with respect to mean stone size and proportion of patients with staghorn, multiple, and bilateral calculi. The normal-weight group, however, had proportionately fewer recurrent stone formers and patients with a history of stone surgery, the authors noted.

Complications occurred in 27%, 11%, 20%, and 17% of normal-weight, overweight, obese, and morbidly obese subjects, respectively. Their average length of hospital stay was three, two, three, and two days, respectively.

Furthermore, costs were comparable in all four groups. The median direct cost per patient was $8,124, $6,746, $6,740, and $6,719 for normal-weight, overweight, obese, and morbidly obese patients, respectively.

Commenting on the new findings, Glenn M. Preminger, MD, professor of urologic surgery and director of the Comprehensive Kidney Stone Center at Duke University Medical Center, Durham, N.C., observed: “The results confirm previous studies demonstrating no increased morbidity for percutaneous nephrostolithotomy in obese stone formers. And the cost data are new and believable. These data go a long way to convince practitioners to proceed with percutaneous nephrostolithotomy as the procedure of choice in managing stones in obese patients.”

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