Chiari malformation Type I surgery in pediatric patients. Part 1: Validation of an ICD-9-CM code search algorithm

Travis R. Ladner, Jacob K. Greenberg, Nicole Guerrero, Margaret A. Olsen, Chevis N. Shannon, Chester K. Yarbrough, Jay F. Piccirillo, Richard C.E. Anderson, Neil A. Feldstein, John C. Wellons, Matthew D. Smyth, Tae Sung Park, David D. Limbrick

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Objective Administrative billing data may facilitate large-scale assessments of treatment outcomes for pediatric Chiari malformation Type I (CM-I). Validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code algorithms for identifying CM-I surgery are critical prerequisites for such studies but are currently only available for adults. The objective of this study was to validate two ICD-9-CM code algorithms using hospital billing data to identify pediatric patients undergoing CM-I decompression surgery. Methods The authors retrospectively analyzed the validity of two ICD-9-CM code algorithms for identifying pediatric CM-I decompression surgery performed at 3 academic medical centers between 2001 and 2013. Algorithm 1 included any discharge diagnosis code of 348.4 (CM-I), as well as a procedure code of 01.24 (cranial decompression) or 03.09 (spinal decompression or laminectomy). Algorithm 2 restricted this group to the subset of patients with a primary discharge diagnosis of 348.4. The positive predictive value (PPV) and sensitivity of each algorithm were calculated. Results Among 625 first-time admissions identified by Algorithm 1, the overall PPV for CM-I decompression was 92%. Among the 581 admissions identified by Algorithm 2, the PPV was 97%. The PPV for Algorithm 1 was lower in one center (84%) compared with the other centers (93%-94%), whereas the PPV of Algorithm 2 remained high (96%-98%) across all subgroups. The sensitivity of Algorithms 1 (91%) and 2 (89%) was very good and remained so across subgroups (82%-97%). Conclusions An ICD-9-CM algorithm requiring a primary diagnosis of CM-I has excellent PPV and very good sensitivity for identifying CM-I decompression surgery in pediatric patients. These results establish a basis for utilizing administrative billing data to assess pediatric CM-I treatment outcomes.

Original languageEnglish
Pages (from-to)519-524
Number of pages6
JournalJournal of Neurosurgery: Pediatrics
Issue number5
StatePublished - May 2016


  • Administrative data research
  • Chiari malformation type I
  • Health services research
  • Neurosurgery
  • Validation studies


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