Below is more detailed information on the methods used for HPV-IMPACT, including our case definition, populations, data collection, and laboratory testing.
A case is defined as a resident in one of the surveillance areas who has a histologically-confirmed diagnosis of cervical intraepithelial neoplasia (CIN) grades 2 or 3, or adenocarcinoma in situ (collectively referred to as CIN2+) and is at least 18 years of age at the time of diagnosis. The date of diagnosis must be on or after January 1, 2008.
Cases are identified based on laboratory reports of CIN2+. Each laboratory in the surveillance area regularly provides laboratory reports of CIN2+ findings to the local site. Because classification for pre-invasive cervical neoplasia is not standardized in the United States, a master list of possible diagnostic codes, terminology, and search terms has been provided to all sites and reporting laboratories to standardize case identification.
We conduct surveillance among 1,552,271 women age 18 and older, and conduct enhanced surveillance among women aged 18-39 years. The table below illustrates the populations under surveillance for each area, as of January 2017.
|EIP site||Catchment area location||Female population aged 18 years and older||Female population aged 18-39 years|
|CA**||8 contiguous cities (Alameda County)||317,735||114,492|
|CT*||New Haven County||352,983||105,995|
|OR**||28 zip codes in Portland Metro (portions of Washington, Multnomah Counties)||272,965||112,726|
*Populations retrieved from the National Center for Health Statistics bridged-race vintage 2015 postcensal file
**Populations were estimated from both the National Center for Health Statistics bridged-race vintage 2015 postcensal file and the American Community Survey’s 2015 census file.
For each case of CIN2+ identified among women aged 18 years or older, a case report form with basic demographic and clinical data is completed. If the case is between the ages of 18-39 years, an enhanced case report form is completed and tissue specimen is collected and sent to CDC for HPV type testing. Additional data collected on the enhanced case report form include race, ethnicity, insurance, cervical cancer screening history, and vaccination history. These data are abstracted through laboratory and medical records.
A portion of tissue that was originally used by a pathologist to diagnose the case is sent to CDC for HPV DNA typing. A pathologist at CDC examines tissue samples to make sure that a high-grade cervical lesion is present on the tissue specimen that was sent. DNA is extracted and tested for 37 HPV types (6, 11, 16, 18, 26, 31, 33, 35, 39, 40, 42, 45, 51, 52, 53, 54, 55, 56, 58, 59, 61, 62, 64, 66, 67, 68, 69, 70, 71, 72, 73, 81, 82, 83, 84, 89, IS39).