Characterisation of children's asthma status by ICD-9 code and criteria-based medical record review.
OBJECTIVE
To characterise the relationship between ICD code-based (i.e. physician diagnosis-based) and criteria-based asthma ascertainment.


METHODS
We compared identification of children with asthma between criteria-based medical record review for asthma ascertainment and an ICD-9 code-based approach. We determined the agreement rate and validity index of ICD code-based asthma ascertainment using asthma status by medical record review as a gold standard.


RESULTS
Of the 115 study subjects, the agreement between medical record review and ICD-9 coding was 81.6% with a kappa value of 0.28 (P<0.0001). Sensitivity, specificity, positive and negative predictive values for ICD-9 code were 24.0%, 97.8%, 75.0%, and 82.0%, respectively, using criteria for asthma by medical record review as gold standard.


CONCLUSIONS
ICD code-based asthma ascertainment appears to under-identify children with asthma compared to criteria-based medical record review. ICD codes may be useful for etiologic research but may not be suitable for surveillance of asthma epidemiology.
Department of Community Pediatric & Adolescent Medicine, Mayo Clinic, Rochester, Minnesota 55944, USA. juhn.young@mayo.edu
Young
Y
Juhn
Amiinah
A
Kung
Robert
R
Voigt
Shirley
S
Johnson
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001249:Asthma / Q000145:classification* / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D038801:International Classification of Diseases / Q000592:standards*; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data*; D010290:Parents; D011237:Predictive Value of Tests; D015995:Prevalence; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D055815:Young Adult