Defining the conditions to generate and send a case report is a fundamental aspect of implementing eCR. PHII and CDC DSTDP recruited an expert panel who deliberated over the criteria that would determine whether a case report should be sent to public health from the EHR. The Council of State and Territorial Epidemiologists (CSTE) position statements for chlamydia and gonorrhea outline criteria sufficient for reporting a case to public health and were the primary guideposts for this effort.

Case reporting and codes

The interaction of the case reporting criteria and the codes that are matched to those criteria is not a one-to-one association. Rather, for chlamydia and gonorrhea, a single diagnosis code might match the criteria while in another case two codes representing the laboratory test performed and the lab result together match the criteria. The expert panel determined the single- and two-factor case detection logic displayed in Table 1 below for reporting cases of chlamydia and gonorrhea. The table includes examples of possible code combinations that should not send a case report.

Table: Examples of single- and two-factor case detection logic for chlamydia and gonorrhea

* Single-factor case detection is based on one value (e.g., a diagnosis code). Two-factor case detection is based on two values that share an association (e.g., code for laboratory test performed and code for test result).

Leveraging value sets for eCR

Each factor alone or in a pair that would result in the creation and sending of a case report is defined by a set of codes called a value set. For example, single-factor case detection based on a chlamydial infection diagnosis represented in Example 1 of Table 1 corresponds to a value set that might include the following ICD-10 codes:

• A56.00 (Chlamydial infection of lower genitourinary tract, unspecified)
• A56.19 (Other chlamydial genitourinary infection)

Case detection based on two-factors requires two value sets, one for each factor. Chlamydia and gonorrhea each require a value set of codes for each factor. This results in eight separate value sets — four for chlamydia and four for gonorrhea.

In theory, a reportable case might be detected by a code for a laboratory test performed in combination with its positive quantitative result. However, the value of quantitative results that indicates a positive result varies from test to test. Consequently, there is no single coded value for quantitative results that can be used for case detection purposes. One option is to utilize the abnormal flag that an EHR creates to indicate an abnormal result. The expert panel decided to not include quantitative test results in this eCR guidance, but to rely on the ELR to capture these cases.