Comparing Two Methods of Estimating Chlamydia Screening Coverage in An Urban Neighborhood, 2009

Background: CDC recommends sexually active females aged <26 be screened annually for Chlamydia trachomatis (Ct). There are no standard means to measure Ct screening coverage.

Objectives: To compare 2 approaches to estimating Ct screening coverage in the New York City neighborhood of Central Brooklyn (CB) in 2009.

Methods: The “indirect method” used public health surveillance data, to ‘back calculate’ the number of sexually active females that must have been screened to yield the total reported Ct cases in CB females aged 15-19 and 20-25 years. Data inputs included: reported number of CB females with ≥1 Ct case in 2009, population estimates, proportion sexually active, and Ct positivity. The “direct method” used electronic health record (EHR) data from 8 CB primary care provider practices using a common EHR which includes a module for sexual behavior documentation. EHR data for females 15-19 and 20-15 were analyzed to determine: unduplicated female clients, proportion sexually active (defined as: Group 1: reported ever having sex; or Group 2: reported ever having sex and/or meeting >1 additional criteria indicative of sexual activity), and number of sexually active females screened for Ct.

Results: Ct screening coverage estimates were: Indirect method: 82% (3,632/4,406; 15-19) and 77% (8,234/10,630; 20-25); EHR method: Group 1: 68% (167/246; 15-19) and 59% (178/302; 20-25), Group 2: 61% (315/514; 15-19) and 57% (518/910; 20-25).

Conclusions: The indirect approach yielded a higher Ct screening coverage estimate than the direct approach. By both methods, screening coverage was higher in the 15-19 than 20-25 age group. For the direct approach, definitions of sexually active women affected measures of screening coverage, particularly for 15-19 year olds.

Implications for Programs, Policy, and Research: The indirect method is easily replicated, with limited resources. The direct method requires more resources and is contingent on consistent, accurate provider documentation of sexual activity.