This data biography includes information about who created this data, and how, where, when, and why it was collected. We (the Assessment, Policy Development, and Evaluation Unit at Public Health – Seattle & King County) created it to help you understand where the data comes from and its strengths and limitations. If you have any further questions, please don’t hesitate to reach out to us at data.request@kingcounty.gov!  

Who collects the data? 

Medicaid enrollment data is collected by the Washington State Health Care Authority (HCA) when an individual enrolls in, renews, or changes their Medicaid health coverage. Medicaid claims data is submitted to HCA by healthcare providers to request reimbursement for a health care visit or service and includes details on services rendered during that visit. 

Who owns the data? 

Medicaid data is owned by HCA, and Public Health – Seattle & King County accesses it through a data sharing agreement with HCA.  

How is the data collected?  

Medicaid enrollment data is gathered through forms submitted by individuals seeking to enroll in or renew Medicaid benefits through one of the five managed care plans of Washington (Amerigroup Washington, Community Health Plan of Washington, Coordinated Care of Washington, Molina Healthcare of Washington, and United Healthcare Community Plan), or for fee-for-service Medicaid coverage. Medicaid claims data, which includes diagnosis and treatment information, is submitted to HCA by healthcare providers following a health care visit or service to request payment for Medicaid-covered services.   

Who is included and excluded from the data?  

The data set includes records on all King County residents enrolled in Medicaid during the past 10 years. While all Medicaid enrollment and claims are included in the data, some information may be missing due to overlapping coverage or enrollment gaps. For instance, if a person was covered by Medicaid for two emergency department visits in February 2019 but had another visit when not covered by Medicaid in December 2019, only two visits would show up from that person in 2019 even though there were actually three visits. Similarly, if a person moves out of King County, their information is no longer included in the data set. 

Where is the data collected? 

Medicaid data is collected throughout the United States, but each state organizes its own Medicaid program. In Washington State, the Medicaid program is called Apple Health. Public Health – Seattle & King County receives Medicaid data for King County residents. This includes services received outside of King County, as long as claims are submitted to the Washington State Health Care Authority. This does not include care that is received in King County by non-King County residents. 

Why is the data collected? 

Medicaid enrollment and claims data are both considered administrative data. Medicaid enrollment data is collected to identify eligible and enrolled individuals in order to administer their benefits. Medicaid claims data is collected primarily for health care billing purposes. In addition to billing, Washington State uses health care claims data for reporting, analytics, and to help the public make their health care decisions. It supports health care and payment reform while addressing the need for cost, quality, and utilization transparency. 

How often is this data collected? 

Medicaid claims data is collected after each medical visit and the initial claim must be submitted within 365 calendar days after the provided service. Currently, King County receives monthly Medicaid data from HCA, which consists of a rolling 12-month refresh of enrollment and claims data. 

What else is important to know about this data?  

The data owner (Washington State Health Care Authority) has given approval for Public Health – Seattle & King County to use this data for public health surveillance, program evaluation, performance measurement, research, and healthcare operations/care coordination. We are allowed to link individual records with other data sources, such as public housing authority data, in order to more wholistically understand individual and community health. 

Where can I learn more about this data?  

Washington State All Payer Claims Database 

Apple Health Client Dashboard  

Medicaid Administrative Data  

About data privacy and security 

The Assessment, Policy Development, and Evaluation Unit takes data security and the privacy of all individuals represented in our data very seriously. Data are stored in a secure environment.  For data sets that are not publicly available, only authorized staff are able to access them. Each data set has privacy guidelines to prevent sharing any information that may be identifiable – for example, not sharing (sometimes called suppressing) numbers when they are very small.