Objective: To determine the validity of calculating the chlamydia Health Plan Employer Data and Information Set (HEDIS) measure using administrative data available in a mixed-model managed care organization (MCO).
Study design: Retrospective cohort study.
Methods: A review of International Classification of Diseases, Ninth Revision (ICD-9), Current Procedural Termin-ology (CPT), Healthcare Common Procedure Coding System (HCPCS), and National Drug Code codes and electronic laboratory files in 1998 and a medical chart review to validate sexual activity and chlamydia testing codes specified by the National Committee for Quality Assurance (NCQA) in 1999 for the chlamydia HEDIS 2000 measure.
Results: Fewer than 25% of female enrollees with laboratory evidence of a chlamydia test had a CPT code for chlamydia testing as specified by the NCQA. Non-pathogen-specific test codes instead of NCQA-specified codes were used in 1998 to code chlamydia tests. By incorporating electronic laboratory data into the automated claims-generating process, all chlamydia tests performed at staff-model clinics were coded. Use of pharmacy dispensing data to identify contraceptive prescriptions increased the proportion of enrollees classified as sexually active by 4% to 5% vs documentation of sexual activity using ICD-9, CPT, and HCPCS codes only.
Conclusions: The MCO quality assurance specialists examining chlamydia testing rates under HEDIS may want to evaluate chlamydia testing coding practices in their MCOs to determine whether simple changes in coding practices may present a more accurate picture of actual testing practices. The proportion of female enrollees classified as sexually active using different data available in the staff and network models varied only slightly.