Background:
Chlamydia is the most frequently reported notifiable infectious disease in the United States which can potentially result in serious health complications if not treated early.

Objective:
To analyze diagnostic methodologies used for chlamydia screening.

Method:
Data on privately insured U.S. women aged 12 to 25 years were extracted from Medstat's MarketScan Databases from 2001 through 2005 using eight Current Procedural Terminology (CPT) codes (87110, 87270, 87320, 87490, 87491, 87810, 87800 and 87801) including six designated for chlamydia screening by NCQA's Health Plan Employer Data and Information Set (HEDIS) measure. Two codes for dual assays, the direct (87800) and amplified (87801) probe techniques for multiple organisms are non-HEDIS codes indicating chlamydia testing as well as testing for other organisms. We calculated chlamydia screening rates and relative frequencies for all the methodologies.

Result:
Screening rates increased significantly each successive year over the period examined. The relative frequencies of direct probe methods (87490 and 87800) declined (53 to 25 percent and 21 to 8 percent respectively). Amplified methods (87491 and 87801) increased (19 to 61 percent and 0.02 to 3 percent respectively) over the years. There was a consistent and statistically significant increase in the estimated screening rates when the non-HEDIS codes (87800 and 87801) were included as diagnostic methods for chlamydia testing. Among the non-HEDIS diagnostic methodology codes, direct probe (87800) was used more frequently than amplified probe (87801) in all five years. The non-specificity of these codes implies that these estimates may not accurately reflect testing for chlamydia.

Conclusion:
The non-specificity of two diagnostic methods (direct and amplified probe for multiple organisms - 87800 and 87801) for chlamydia testing present a challenge in estimating screening rates from private insurance claims databases.

Implications:
Standardizing CPT code assignments to indicate organism-specific diagnostic methods would enable more accurate analyses of screening.