Validation of administrative data used for the diagnosis of upper gastrointestinal events following nonsteroidal anti-inflammatory drug prescription.
OBJECTIVE
To validate veterans affairs (VA) administrative data for the diagnosis of nonsteroidal anti-inflammatory drug (NSAID)-related upper gastrointestinal events (UGIE) and to develop a diagnostic algorithm.


METHODS
A retrospective study of veterans prescribed an NSAID as identified from the national pharmacy database merged with in-patient and out-patient data, followed by primary chart abstraction. Contingency tables were constructed to allow comparison with a random sample of patients prescribed an NSAID, but without UGIE. Multivariable logistic regression analysis was used to derive a predictive algorithm. Once derived, the algorithm was validated in a separate cohort of veterans.


RESULTS
Of 906 patients, 606 had a diagnostic code for UGIE; 300 were a random subsample of 11 744 patients (control). Only 161 had a confirmed UGIE. The positive predictive value (PPV) of diagnostic codes was poor, but improved from 27% to 51% with the addition of endoscopic procedural codes. The strongest predictors of UGIE were an in-patient ICD-9 code for gastric ulcer, duodenal ulcer and haemorrhage combined with upper endoscopy. This algorithm had a PPV of 73% when limited to patients >or=65 years (c-statistic 0.79). Validation of the algorithm revealed a PPV of 80% among patients with an overlapping NSAID prescription.


CONCLUSIONS
NSAID-related UGIE can be assessed using VA administrative data. The optimal algorithm includes an in-patient ICD-9 code for gastric or duodenal ulcer and gastrointestinal bleeding combined with a procedural code for upper endoscopy.
Abraham
N S
NS
Houston Center for Quality of Care and Utilization Studies, Section of Health Services Research, Houston, TX, USA. nabraham@bcm.tmc.edu
Cohen
D C
DC
Rivers
B
B
Richardson
P
P
D000465:Algorithms; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects*; D015331:Cohort Studies; D016099:Endoscopy, Gastrointestinal; D005260:Female; D005767:Gastrointestinal Diseases / Q000139:chemically induced* / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D041742:Upper Gastrointestinal Tract
D000894:Anti-Inflammatory Agents, Non-Steroidal