Validation of ICD-9-CM codes to identify gastrointestinal perforation events in administrative claims data among hospitalized rheumatoid arthritis patients.
OBJECTIVE
To validate, using physician review of abstracted medical chart data as a gold standard, a claims-based algorithm developed to identify gastrointestinal (GI) perforation cases among rheumatoid arthritis (RA) patients.


METHODS
Patients with established RA, aged 18 years or older with hospital admissions between January 2004 and September 2009, were selected from a large US-hospital-based database. An algorithm with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes for GI perforation and combinations of GI-related diagnosis codes and Current Procedural Terminology (CPT-4) procedure codes for relevant GI surgeries was used to identify potential GI perforation cases. Two senior experienced specialist physicians independently reviewed abstracted chart data and classified cases as confirmed or unconfirmed GI perforations. Positive predictive values (PPVs) to identify confirmed GI perforation were calculated and stratified by upper versus lower GI tract.


RESULTS
Overall, 86 of 92 GI perforation cases were confirmed, yielding an overall PPV of 94% (95%confidence interval [CI] = 86%-98%). PPV was 100% (95%CI = 100%-100%) for upper GI perforation (esophagus, stomach) and 91% (95%CI = 90%-97%) for lower GI perforation (small intestine, PPV = 100%; large intestine, PPV = 94%; unspecified lower GI, PPV = 89%).


CONCLUSIONS
This algorithm, consisting of a combination of ICD-9-CM diagnosis and CPT-4 codes, could be used in future safety studies to evaluate GI perforation risk factors in RA patients.
Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, FOT 805D, 510 20th Street South, Birmingham, AL 35294, USA. jcurtis@uab.edu
Jeffrey R
JR
Curtis
Shih-Yin
SY
Chen
Winifred
W
Werther
Ani
A
John
David A
DA
Johnson
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology / Q000473:pathology; D059019:Clinical Coding / Q000706:statistics & numerical data*; D016001:Confidence Intervals; D039702:Current Procedural Terminology; D016208:Databases, Factual; D016021:Epidemiologic Studies; D004939:Esophageal Perforation / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006760:Hospitalization; D006801:Humans; D007345:Insurance Claim Review / Q000706:statistics & numerical data*; D038801:International Classification of Diseases / Q000706:statistics & numerical data*; D007416:Intestinal Perforation / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D015233:Models, Statistical; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055815:Young Adult