Objectives: To assess state variations in eligibility criteria based on enrollment length and sexual activity on chlamydia testing rates among Medicaid female enrollees aged 15 to 25 years and potential impact of the representatives of testing rates.

Methods: We used 2010 Medicaid Analytic eXtract to estimate and compare the overall and state-level prevalence of gaps in coverage of ≥ 2 consecutive months, service utilization associated with sexuality, and chlamydia testing rates among Medicaid female enrollees aged 15 to 25 years who had ≥ 1 month of the full scope of Medicaid benefits and had ≥ 1 health service claim. The chlamydia testing rate was calculated as the proportion of sexually active Medicaid female enrollees who received a chlamydia test in 2010.

Results: Of 5.7 million women aged 15 to 25 years enrolled in Medicaid in 2010, 42.3% had a 2-month gap of enrollment coverage in 2010. The proportion of women who had a 2-month gap varied from 26.1% to 73.2% across states. The proportion of women identified as sexually active was 59.8% among women who had a 2-month gap and 57.1% among women who had no 2-month gap. The chlamydia testing rate was 44.0% among sexually active women with a 2-month gap and 44.2% among sexually active women without a 2-month gap. Eleven states had ≥10% difference in sexual activity or chlamydia testing rates between women with a 2-month gap and women without a 2-month gap.

Conclusions: States which exclude a substantial proportion of Medicaid enrollees from inclusion in the chlamydia testing denominator may have less representative testing estimates because those excluded tend to be women aged 19 to 25 years.