Table 1.

Descriptions of types of laboratory facilities

Stratum (n)	Description of type of laboratories	Why selected as a stratum
Physician office (7,627)	-Tests performed in physician office (PO) setting; results typically shared during visit -Practices are often small but can be quite large (2 or 3 to 200 providers) -May conduct only rapid tests or operate labs like those in hospitals	-Highest number of facilities that met inclusion criteria -Patient population with CKD risk factors (diabetes and hypertension)
Hospital (6,574)	-Tests performed include those needed in emergency situations and those done in high enough volume to warrant acquisition of necessary equipment -May be segmented by chemistry, pathology, other specialty divisions -Usually proportionate in size to the population it serves; generally used by all inpatients at particular hospital and many outpatients seen by physicians with offices in hospital -Send some tests to reference laboratories if demand is low	-Second-highest number of facilities that met inclusion criteria
Independent (2,174)	-Blood chemistry analyses and urinalyses are some of most frequently requested tests -Generally conduct high routine and specialty test volumes; often operate all day/week -Private, commercial facilities, including two largest national providers, Quest Diagnostics and LabCorp; at least 35 other companies exist -Also known as reference laboratories; most tests requested from POs and hospitals	-Third-highest number of facilities that met inclusion criteria
Community clinic (986)	-Labs that are on-site at community clinics -Labs perform tests on samples drawn from patients on site; some samples sent to reference labs for testing -Patients typically get results during follow-up visits	-Serve populations disproportionately affected by CKD risk factors -Fourth-highest number of facilities that met inclusion criteria (excluding CLIA’s “other” category)
Health fair Insurance Public health (28)	-Health fair labs are set up as part of a health fair, health assessment, or health risk reduction program; can include lipid testing, measurement for prostate specific antigen, and comprehensive chemistry panels. Usually operated by a clinical lab, under special permit, and must follow strict procedural and management guidelines -Insurance labs perform tests required by insurance companies to determine whether to extend coverage or to pay a claim -Public health labs typically function to safeguard communities via monitoring communities for pathogens that spread via food/people/animals, testing to detect and monitor newly emerging infectious diseases, etc.	-Exceptionally high mean annual routine chemistry volumes (ranging from 524,460 to 1,658,704)
Other (3,143)	-Mix of remaining lab types: ambulatory surgery center, comprehensive outpatient rehabilitation facility, ancillary testing site in health care facility, end stage renal disease dialysis facility, health maintenance organization, home health agency, hospice, industrial, intermediate care facility for mentally retarded, mobile laboratory, pharmacy, school/student health service, skilled nursing facility/nursing facility, other practitioner, tissue band/repositories, blood banks, rural health clinics, federally qualified health centers, ambulance, and other	-Catch all for remaining laboratories, including CLIA’s “other” category