Victoria Udalova  Dennis Linders (presenter)  Alice Zawacki  Kate Vavra-Musser  @ FCSM 2022

Enhancing Health Data (EHealth) Program, U.S. Census Bureau

Developing a Physician-Employer Linked Database

Any opinions and conclusions expressed herein are those of the authors and do not reflect the views of the U.S. Census Bureau. 

This presentation does not include any confidential data. 
Project Motivation

The business of health care is 

rapidly evolving, but stakeholders 

tell us not enough is known about 

the impact of these changes on 

care (cost, quality, access), the 

workforce, and local markets.

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Knowledge gaps Project aims

These gaps in knowledge are 

in part due to the absence of a 

definitive source of data on the 

supply of health care; existing

datasets present a range of

tradeoffs and limitations. 

Data gaps

“Even seemingly simple 

concepts, such as the 

number of practitioners may 

be more slippery than 

researchers realize.” 

(Maurer et al. HSR 2021)

Industry 

consolidation + 

vertical integration

Shift of physicians 

from owners to 

employees

Growing reliance 

on healthcare 

staffing agencies

Changing 

regulatory 

environment (ACA)

Growing 

involvement of 

private equity

Impact of COVID19 pandemic

Census does not have all the 

answers either—and is not principally 

focused on health—but we can use 

our unique data linking infrastructure 

to enhance data on physicians and 

their employers with our rich data on 

the American people and economy.

BUSINESS TRENDS

Affiliated 

Institutions Physicians

taxpayers

employees

residents

employers

taxpayers

businesses

Data linking infrastructure

Data on people + economy
employers industry 

classification

parent

physicians

race + 

ethnicity

residence + 

commute

specialty

income + 

wages

place of 

birth

licensing + 

credentials

employer(s)

selfemployment age + 

gender

patients + 

procedures

place of 

employment

billing

revenue + 

visits

patients + 

procedures

quality + 

performance

physical 

establishments

legal form + 

govt owned

locations

birth + death

ownership 

changes

payroll + 

employees

independent

validation

place external 

data into new 

context

new insights new insights

Operationalize Census’ unique assets to enhance data and contribute novel insights on physicians and their employers

Vision: Integrated Data on Physicians and their Employers

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Time dimension: Initial work focused on 2018 pre-pandemic baseline, but data joining process is repeatable across years

(incl. self-employment)

All data releases are subject to disclosure avoidance reviews to protect privacy of individual physicians and businesses. 
Universal registry of 

healthcare providers

Individual wage and 

tax statements linking 

workers to employers

Comprehensive DB of 

business establishments

Integrating Restricted Administrative Records

PIK EIN

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Universal registry of 

healthcare providers

Individual wage and 

tax statements linking 

workers to employers

Comprehensive DB of 

business establishments

Over 5 million active 

records for practitioners 

ranging from physicians 

to athletic trainers. Also 

1.5 million registered 

organizations.

Used to assign a unique 

“National Provider 

Identifier” (NPI) to each 

health care practitioner—

mandated by HIPAA and 

launched in 2005. 

PIK EIN

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Integrating Restricted Administrative Records
Universal registry of 

healthcare providers

Individual wage and 

tax statements linking 

workers to employers

Comprehensive DB of 

business establishments

We use a protected 

version of NPPES to 

identify each 

physician’s “Protected 

Identification Key”(PIK)

so we can link to other 

Census records.

This PIK can be linked 

to IRS Form W-2 data to 

identify wage and 

Employer Identification 

Number (EIN), which 

can be linked to the BR.

PIK EIN

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Integrating Restricted Administrative Records
Universal registry of 

healthcare providers

Individual wage and 

tax statements linking 

workers to employers

Comprehensive DB of 

business establishments

Consistently updated 

since 1972 using 

administrative records 

from the IRS, the SSA, 

and the BLS. 

Covers 5 million single 

establishment firms, 

160,000 multiestablishment firms with 

1.8 million 

establishments, and 21 

million non-employers.

Provides info on 

geography; industry, 

legal, and organization 

classification; and activity

(payroll, employees, 

sometimes revenue)

PIK EIN

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Integrating Restricted Administrative Records
Connecting the Dots: The Challenge

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 Organizational structures and affiliations can look 

very different in different administrative datasets 

because they are generated for different 

purposes and from different perspectives. 

 Easy to track a one-physician practice that has 

operated out of the same location for decades:

 All competing perspectives look largely the same 

(ex: ownership vs. service delivery vs. payroll)

 Difficult to track physicians working for complex, 

evolving health systems: 

 Payroll and employment may be indirect (staffing agency).

 Client services can be provided in multiple locations—or 

even virtually via telemedicine.

 Billing, health records, and other administrative functions may 

be outsourced or centralized in a different location. 

 Ownership and affiliations may be complicated and multifaceted due to frequent mergers & acquisitions, vertical 

integration, and involvement of private equity.

ADMIN

STRUCTURE

PHYSICAL 

SERVICE 

DELIVERY

OWNERSHIP

STRUCTURE

TAX 

STRUCTURE

BILLING

PAYROLL

BLIND MEN AND THE ELEPHANT (INDIAN PARABLE)
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EIN 1

Physical 

Establishment 

1

Physical 

Establishment 

2

EIN 3

Physical 

Establishment 

4

Physical 

Establishment 

5

EIN 2

Physical 

Establishment 

3

= Subsidiary

Firm 1

Connecting the Dots: Benefits of the Business Register

ownership “firm”

payroll “EIN” tax unit

physical service delivery “physical establishment”

Key linkage challenge: We link physicians to businesses at the EIN 

using an algorithm to place physicians with their establishment(s) that 

leverages various geographic identifiers.

(ex: known work addresses, residence, state of license, etc.)

A key benefit of the Business Register is that it 

explicitly splits out, tracks, and links together 3 

main lenses on businesses:
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Additional Linkages

Census

Bureau

Numident

IRS 1040 + 

IRS 1099

Decennial 

Census + 

ACS

Master 

Address

File

PIK

PIK

PIK

PIK

businesses

income + 

wages

retirement

self 

employment

race /

ethnicity

education

(sample)

employment

(sample)

other 

demographics

place of 

origin

birth / 

death

geo

references residence commute

CMS 

Medicare

Open Data

NPI practice

addresses

affiliations 

+

credentials

patients +

procedures

EMP

EMP patient

visits

patient

care

revenues

operating

expenses

entrants / 

exits / 

age

firm

revenue

mergers + 

aq’s

X

health

system

linkages

health

system

details

hospital

details

Longitudinal

Business 

DB

AHRQ 

Compendium 

of US Health 

Systems

Service 

Annual 

Survey

Note: Restricted data have been processed at the Census Bureau to replace 

personally identifying information with anonymized linkage keys.

physicians

Linkage in the works

Linkage in the works
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From Infrastructure to Insights: Setting Priorities

Priority Questions Public Data Products

Our focus is on building an enabling 

data infrastructure so that we can 

empower partners with enhanced data 

and better answers to their most 

pressing questions.

What partners or projects would most 

benefit from leveraging this new data 

asset—and how can we best 

collaborate?

Partnerships

We also seek to inform the public by 

synthesizing and publicly sharing key 

national and community-level findings 

as aggregate statistics.

Privacy protections permitting, what 

key facts and trends would be most 

valuable to share publicly and 

update regularly?

The role of the US Census Bureau is to 

use our assets and capabilities to help 

stakeholders—researchers, 

governments, and the public—answer 

important questions.

What important questions and 

information needs are our data best 

positioned to help answer? 

How have the employers 

and employment 

patterns of physicians 

changed over time—

particularly pre and post 

COVID-19.

Which communities have 

seen the most employer 

consolidation and how 

does this impact patient 

services (ex: access) 

and physician earnings?

How do urban and rural 

communities differ in the 

structure, ownership, 

and distribution of 

institutions that employ 

physicians?

How well do physicians 

reflect the communities 

that they serve (such as 

by race/ethnicity), and 

how does this differ by 

community or specialty? 

What share of US 

physicians are 

employed outside of 

traditional health 

care firms and what 

Sample Qs

do they do?

? ? ?
version 1.0

Project Status and Future Work

 Completing initial linkage phase of 

building core integrated dataset (focus: 

enabling comparisons over time).

 Drafting working paper that transparently 

documents the “1.0” linkage process, 

with sample exhibits.

 Initiating stakeholder interviews to better 

understand stakeholder needs and 

opportunities for collaboration.

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 Continue to enhance coverage of 

physicians and their organizations by 

linking in additional (partner) data.

 Compare our dataset to existing datasets

that place physicians with organizations—

and understand differences.

 Implement advanced privacy preservation 

strategies and techniques to enable public 

reporting at low levels of geography.

Current Activities Future Work version 2.0+
Website: https://www.census.gov/programs-surveys/ehealth.html

Contact: Dennis Linders

EHealth Program Data Scientist

dennis.linders@census.gov