Validation of a Case-Finding Algorithm for Hidradenitis Suppurativa Using Administrative Coding from a Clinical Database.

BACKGROUND

Requisite to the application of clinical databases for observational research in hidradenitis suppurativa (HS) is the identification of an accurate case cohort.

OBJECTIVE

To assess the validity of utilizing administrative codes to establish the HS cohort from a large clinical database.

METHODS

In this retrospective study using chart review as the reference standard, we calculated several estimates of the diagnostic accuracy of at least 1 ICD-9 code for HS.

RESULTS

Estimates of the diagnostic accuracy of at least 1 ICD-9 code for HS include sensitivity 100% (95% CI 98-100), specificity 83% (95% CI 77-88), positive predictive value 79% (95% CI 72-85), negative predictive value 100% (95% CI 98-100), accuracy 90% (95% CI 86-93), and kappa statistic 79% (95% CI 73-86).

CONCLUSION

The case-finding algorithm employing at least 1 ICD-9 code for HS provides balance in achieving accuracy and adequate power, both necessary in the evaluation of a less common disease and its potential association with uncommon or even rare events.