title: Using the CUSUM test to control the proportion of inadequate open biopsies of musculoskeletal tumors.
abstract: BACKGROUND
  Biopsies of musculoskeletal tumors lead to alterations in treatment in almost 20% of cases. Control charts are useful to ensure that a process is operating at a predetermined level of performance, although their use has not been demonstrated in assessing the adequacy of musculoskeletal biopsies.
  
  
  OBJECTIVE
  We therefore (1) assessed the incidence of and the reasons for inadequate musculoskeletal biopsies when following guidelines for performing the procedure; and (2) implemented a process control chart, the CUSUM test, to monitor the proportion of inadequate biopsies.
  
  
  METHODS
  We prospectively studied 116 incisional biopsies. The biopsy was performed according to 10 rules to (1) minimize contamination in the tissues surrounding the tumor; and (2) improve accuracy. A frozen section was systematically performed to confirm that a representative specimen was obtained. Procedures were considered inadequate if: (1) another biopsy was necessary; (2) the biopsy tract was not appropriately placed; and (3) the treatment provided based on the diagnosis from the biopsy was not appropriate.
  
  
  RESULTS
  Five (4.3%) of the 116 incisional biopsy procedures were considered failures. Three patients required a second repeat open biopsy and two were considered to receive inappropriate treatment. No alarm was raised by the control chart and the performance was deemed adequate over the monitoring period.
  
  
  CONCLUSIONS
  The proportion of inadequate musculoskeletal open biopsies performed at a referral center was low. Using a statistical process control method to monitor the failures provided a continuous measure of the performance.
authors.affiliation: Department of Orthopaedic Surgery, Hospital Cochin, Paris, France. djmbiau@yahoo.fr
authors.forename: David J
authors.initials: DJ
authors.lastname: Biau
authors.forename: Kurt R
authors.initials: KR
authors.lastname: Weiss
authors.forename: Rej S
authors.initials: RS
authors.lastname: Bhumbra
authors.forename: Darin
authors.initials: D
authors.lastname: Davidson
authors.forename: Chris
authors.initials: C
authors.lastname: Brown
authors.forename: Jay S
authors.initials: JS
authors.lastname: Wunder
authors.forename: Peter C
authors.initials: PC
authors.lastname: Ferguson
mesh_terms: D000328:Adult; D001706:Biopsy / Q000592:standards*; D001859:Bone Neoplasms / Q000473:pathology* / Q000628:therapy; D003951:Diagnostic Errors / Q000517:prevention & control; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D019042:Muscle Neoplasms / Q000473:pathology* / Q000628:therapy; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D019984:Quality Indicators, Health Care / Q000592:standards*; D012017:Referral and Consultation / Q000592:standards; D062606:Tertiary Care Centers / Q000592:standards; D019564:Unnecessary Procedures