Table 2.

Identified and Confirmed Nonmelanoma Skin Cancer Cases and Positive Predictive Values, by Algorithm, 1988–2007 All-Payer Claims Data, Henry Ford Health System, Detroit, Michigan

Identification Algorithm	No. of Identified Cases	No. of Confirmed True Cases	PPV	95% CI
ICD-9-CM code alone	349	164	0.470	0.418, 0.522
CPT code alone	334	245	0.734	0.686, 0.781
Both ICD-9-CM and CPT codes	297	282	0.949	0.925, 0.974

Abbreviations: CI, confidence interval; CPT, Current Procedural Terminology; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; PPV, positive predictive value.