title: Percutaneous Nephrolithotomy in the Superobese: A Comparison of Outcomes Based on Body Mass Index.
abstract: Percutaneous nephrolithotomy (PCNL) is considered the gold standard for treatment of large renal calculi. Although several investigators have examined the feasibility and outcomes associated with PCNL in obese patients, these studies have been limited by small sample size, lack of a comparator group, or few patients at body mass index (BMI) extremes. We thus compared outcomes of superobese (BMI >50) patients undergoing PCNL vs both an "overweight" and "ideal" cohort.
  
  
  
  We used a prospectively maintained database to identify ideal (BMI 18.5-25), overweight (BMI 25.1-49.9), and superobese (BMI ≥50) patients who underwent PCNL. Our primary objective was to compare surgical outcomes between groups measured by the percent of patients who required secondary PCNL. We then compared complication rates, need for transfusion, and length of stay (LOS) using chi-square testing and ANOVA where appropriate.
  
  
  
  A total of 1152 patients were identified of which 254 were classified as ideal, 840 as overweight, and 58 as superobese. The overweight cohort had a higher mean age and greater proportion of males, whereas staghorn stones were more common in the superobese group. Comorbid conditions were more commonly observed in the superobese cohort. Otherwise, the groups were similar. Surgical outcomes were comparable with 47.2%, 42.0%, and 38.0% of ideal, overweight, and superobese patients requiring secondary PCNL (p = 0.25) with no difference in complication rates, need for transfusion, or LOS.
  
  
  
  PCNL can be effectively and safely performed in superobese patients with no difference in surgical outcomes or complications when compared to ideal or overweight patient cohorts.
authors.affiliation: Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana.
authors.forename: Casey A
authors.initials: CA
authors.lastname: Dauw
authors.affiliation: Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Borofsky
authors.affiliation: Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana.
authors.forename: Nadya
authors.initials: N
authors.lastname: York
authors.affiliation: Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana.
authors.forename: James E
authors.initials: JE
authors.lastname: Lingeman
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001803:Blood Transfusion / Q000706:statistics & numerical data; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000601:surgery*; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000009:adverse effects*; D009767:Obesity, Morbid; D017063:Outcome Assessment, Health Care; D050177:Overweight; D011183:Postoperative Complications; D012189:Retrospective Studies; D016896:Treatment Outcome