RESEARCHERS’ GUIDE TO VA DATA

2010-2011 VIReC Database and 

Methods Cyber Seminar Series

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RESEARCHERS’ GUIDE TO VA DATA

Using VA Corporate Data 

Warehouse to Assess Vitals

March 7, 2011

Polly Hitchcock Noël, PhD 

VERDICT & UT Health Science Center at San Antonio

San Antonio, Texas

Laurel Copeland, PhD

Center for Applied Health Care – CTVHCS & Scott & White

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2010-2011 VIReC Database and Methods Cyber Seminar Series
RESEARCHERS’ GUIDE TO VA DATA

Session Objectives

At the end of this session, the participant will 

be able to:

Identify current approaches to assessing 

vitals using the Corporate Data Warehouse

Describe limitations of using the Corporate 

Data Warehouse to assess vitals

Describe recent research and methods used 

to assess vitals that have used the Corporate 

Data Warehouse

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RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in CDW vitals 

data 

Evaluations of CDW data

Case study: CDW anthropometric data

Case study: CDW blood pressure data

Recommendations

Where to Go for More Help 

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RESEARCHERS’ GUIDE TO VA DATA

Audience Poll

(Heidi please convert to poll)

How would you rate your overall knowledge of the Corporate 

Data Warehouse (CDW)?

– 1 (No knowledge)

– 2

– 3

– 4

– 5 (Expert-level knowledge)

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RESEARCHERS’ GUIDE TO VA DATA

White Board

What do you want to learn about the CDW or what data do you 

want to get from the CDW?

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RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in CDW vitals 

data 

Evaluations of CDW data 

Case study: CDW anthropometric data

Case study: CDW blood pressure data

Recommendations

Where to Go for More Help

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RESEARCHERS’ GUIDE TO VA DATA

Examples of research topics requiring 

information on “vitals” data

Quality of Care

– Does patient BMI class predict receipt of 

recommended preventive screenings? 

Healthcare disparities

– Is hypertension an independent predictor of 

survival disparity among African American and 

white veterans with schizophrenia?

Implementation research

– Can quality of chronic pain management be 

improved by implementation of the PCMH? 

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RESEARCHERS’ GUIDE TO VA DATA

Corporate Data Warehouse

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draws from several VHA clinical & 

administrative systems

created to support administrative & research 

objectives

historical data from FY 1999, current data 

added nightly

additional domains will be added in future

relational database, unlike some other 

national repositories in VHA
RESEARCHERS’ GUIDE TO VA DATA

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Data found in the CDW

Patient demographics (VistA/All time)

Staff demographics (VistA/All time)

Outpatient encounters (NPCD/10/1/1999)

– All ICD9 Codes

– All CPT Codes

Vital Signs (RDW/From 10/1/1999)

Allergies (RDW/From 10/1/1999)

Outpatient Pharmacy (RDW/From 10/1/1999)

– Loading

Surgical Procedures (VistA/All time)

Non VA Meds (VistA/All time)

Prosthetics (VistA/All time)
RESEARCHERS’ GUIDE TO VA DATA

Vital Signs Available from CDW

(with abbreviations used in the CDW database) 

– Audiometry (AU) 

– Blood pressure (BP)

– Circumference/girth 

(CG)

– Central venous pressure 

(CVP) 

– Fundal height (FH) 

– Fetal heart tones (FHT) 

– Hearing (HE) 

– Height (HT)

– Pain (PA)

– Pulse oximetry (PO) 

– Respiration (RE) 

– Temperature (TE) 

– Tonometry (TO) 

– Vision corrected (VC) 

– Ventilator minute 

volume (VMV) 

– Ventilator tidal 

volume (VTV) 

– Vision uncorrected 

(VU) 

– Weight (WT)

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RESEARCHERS’ GUIDE TO VA DATA

Vital Sign History (VistA/RDW)

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Perrin R, Bates J, Noel PH, Copeland LA, Lancaster B. National Clinical Data for VA Research: the VA 

Corporate Data Warehouse. Workshop. February, 2008 National HSR&D Meeting, Baltimore, MD.

Blue=All Time Red=2007-2009
RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in CDW vitals 

data

Evaluations of CDW data

Case study: CDW anthropometric data

Case study: CDW blood pressure data

Recommendations

Where to Go for More Help 

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RESEARCHERS’ GUIDE TO VA DATA

Tracing Path of CDW Data

Vitals data assessed & entered into CPRS 

Data stored in local VistA systems

Transmitted by HL 7 messages to 1 of 4 

Regional Data Repositories (RDW’s)

CDW extracts, transforms, and loads data 

from RDW’s into its SQL data fields

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RESEARCHERS’ GUIDE TO VA DATA

Tracing Path of CDW Data

CDW is regularly updated (refreshed)

Does not hold stable reference files

Errors & out of range values are not 

cleaned 

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RESEARCHERS’ GUIDE TO VA DATA

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Possible Sources of Error

Measurement/Reporting

Data Entry

Data Transfer or Extraction
RESEARCHERS’ GUIDE TO VA DATA

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Possible Sources of Error:

Measurement/Reporting 

Equipment incorrectly calibrated

Reliance on patient self-report vs. clinician 

measurement

Values rounded “up” or “down”

Patients measured inconsistently with or 

without shoes, clothing, etc.

Last entered height carried forward

Weights and/or heights less likely to be 

measured for specific patient populations
RESEARCHERS’ GUIDE TO VA DATA

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Possible Sources of Error:

Data Entry

Transposition of numbers 

Keying of number adjacent to intended target

Addition/deletion of digits 

Erroneous transformation of values 
RESEARCHERS’ GUIDE TO VA DATA

Possible Sources of Error:

Data Transfer or Extraction

Specific to the VA, the “same” 

anthropometric data entered into CPRS may 

exist at several levels

– local VistA systems 

– VISN data warehouses (directly from VistA or 

from a collector/feeder database on a SQL 

server connected to VistA)

– CDW (from VistA via RDW)

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RESEARCHERS’ GUIDE TO VA DATA

Possible Sources of Error: 

Data Transfer or Extraction

Variations between sources can arise

– Data can be lost in transmission

– Different filters can result in inclusion of slightly 

different subsets of data

– Refresh differences - VistA/CDW constantly 

changing; updates not done simultaneously by 

all warehouses

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RESEARCHERS’ GUIDE TO VA DATA

Possible Sources of Error: 

Data Transfer or Extraction

Numeric data can be redefined as character 

data or “rounded” if stored with smaller 

number of decimal places

– Out-of-range & outlier values not cleaned in 

CDW, data appear in both text & numeric form

– Text field “as is” from VistA extraction

– Numerical field based on a very conservative 

transformational algorithm

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RESEARCHERS’ GUIDE TO VA DATA

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Possible Sources of Error: 

Data Transfer or Extraction

Programmer error

– Programmer may misinterpret variables or 

cases needed or investigator may mis-specify 

needs

– Research team may fail to request variable to 

differentiate inpatient from outpatient 

measurements
RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in CDW vitals 

data 

Evaluations of CDW data

Case study: CDW anthropometric data

Case study: CDW blood pressure data

Recommendations

Where to Go for More Help 

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RESEARCHERS’ GUIDE TO VA DATA

Evaluation of CDW Data:

Administrative Project

VHA Support Service Center (VSSC) 

1) Compared CDW data fields to one another and 

to overall patient utilization over time to see if 

populated as expected

2) Examined data for biologically implausible 

values

3) Compared data from 10 facilities (CDW vs. 

VISN warehouse)

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RESEARCHERS’ GUIDE TO VA DATA

Evaluation of CDW Data: 

are CDW data fields populated 

as expected over time?

Comparison of VHA utilization and CDW data over 4 years

2004

N

2005

N

2006

N

2007

N

Unique Patients 4,976,773 5,094,494 5,188,836 5,230,452

Blood Pressure 31,598,526 33,029,724 34,293,140 35,276,799

Circumference/Girth 11,004 16,933 82,482 125,577

Central Venous Pressure 17,344 16,018 64,988 79,737

Height 8,534,729 8,521,504 7,435,312 6,266,231

Pain 32,130,438 34,926,122 36,150,234 37,062,161

Pulse Oximetry 3,233,096 3,869,444 7,746,200 12,903,893

Pulse 29,468,149 30,613,107 31,590,314 32,501,113

Respiration 25,680,395 26,623,272 27,117,212 27,519,501

Temperature 25,358,389 26,100,279 26,382,625 26,715,839

Weight 14,764,754 15,258,657 15,490,210 15,497,385

Adapted from Perrin R, Bates J, Noel PH, Copeland LA, Lancaster B. National Clinical Data for VA Research: the VA 

Corporate Data Warehouse. Workshop. February, 2008 National HSR&D Meeting, Baltimore, MD.
RESEARCHERS’ GUIDE TO VA DATA

Evaluation of CDW Data:

Research Project

HSR&D-funded IIR (Obesity Care Practices in 

Veterans Healthcare Administration)

1) Compared number & values of CDW vs. VISN 

warehouse height & weight data

2) Examined implausible variation in repeated 

measurements recorded in the CDW on the 

same day, and on the same year, for the same 

individuals
RESEARCHERS’ GUIDE TO VA DATA

Evaluation of CDW Data: 

CDW vs. VISN data warehouse

Percent concordance in # of wt records for N* individuals appearing in 

both CDW & VISN data warehouses for 3 Fiscal Years (FY)

VISN A VISN C VISN E VISN F

N (%) N (%) N (%) N (%)

FY2002 97,375 (98.6) 81,125 (62.3) 106,010 (99.3) 158,088 (99.5) 

FY2004 34,815 (98.3) 31,988 (98.5) 47,572 (99.2) 77,233 (99.4) 

FY2006 30,812 (97.5) 28,289 (97.5) 41,944 (98.4) 68,592 (98.2) 

*Note: FY2002 data based on patients with > 1 pc visits in FY2002, FY2004 & FY2006 

data based on pc patients identified as obese in FY2002
RESEARCHERS’ GUIDE TO VA DATA

Evaluation of CDW Data:

Implausible variation in 

repeated measurements

Frequency distribution of differences in minimum & maximum 

CDW hts recorded same day & same year (FY2006)

Difference 

in inches

occurrences of individuals with 

> 2 hts recorded same day 

N=33,424

individuals with > 2 hts 

recorded same year

N=539,489

N (%) N (%)

difference = 0 29,319 (87.72) 469,226 (86.98) 

0 < difference < 1 1,771 ( 5.30) 42,186 ( 7.82) 

1 < difference < 2 764 ( 2.28) 14,302 ( 2.65) 

2 < difference < 10 1,207 ( 3.61) 11,063 ( 2.05) 

Difference > 10 363 ( 1.09) 2,712 ( 0.50) 
RESEARCHERS’ GUIDE TO VA DATA

Overall findings from administrative & 

research project evaluations

Weights > Heights > WC

Some anomalies identified & corrected as 

result of administrative project

Concordance between the number & values of 

hts & wts stored in CDW & VISN warehouses 

generally 97.5%-99.9%

Biologically implausible values noted, as well 

as biologically improbable variation
RESEARCHERS’ GUIDE TO VA DATA

Summary

In spite of occasional anomalies, CDW 

appears to reliably reflect hts & wts recorded 

in VistA/VISN-level sources

Probable data errors appear to be present in 

both data sources

CDW valuable & useful source of nationwide 

vital sign & anthropometric data

Noel et al., JRRD 2010;47(8):739-250
RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in CDW vitals 

data 

Evaluations of CDW data

Case study: CDW anthropometric data

Case study: CDW blood pressure data

Recommendations

Where to Go for More Help 

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RESEARCHERS’ GUIDE TO VA DATA

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Case Study: Anthropometric Data

Obesity Care Practices in the Veterans Health 

Administration (HSR&D IIR 05-121)

Study Objectives

describe variations in VHA obesity care practices 

identify factors that predict these variations

examine the impact of care practices on BMI 

trends & other clinical outcomes 

Noel et al., JGIM 2010;25(6):510-516.
RESEARCHERS’ GUIDE TO VA DATA

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Challenges

Height (& weight) data inherently variable 

over time

To detect changes in height & weight that are 

“real” vs. those due to error

When errors detected or suspected

– find valid/consistent way to eliminate or 

neutralize OR to understand how it may affect 

findings/interpretation
RESEARCHERS’ GUIDE TO VA DATA

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Methods

Original plan: 

Identify obese cohort BMI > 30 in FY2002 

(and follow through FY2006):

– last recorded weight in FY02 

– last recorded height in FY02 (or 1st available in 

FY03-FY06)

Included use of filtering scheme to remove 

“biologically implausible” weights (Das et al., 

2005)

– deleted all weights > 700 lbs & < 75 lbs 

– deleted all heights > 84 in & < 48 ins
RESEARCHERS’ GUIDE TO VA DATA

Limitations of Data: 

Impact on Cohort Identification

Patients with: N (%)

> 1 primary care visits in FY2002 in 6 VISNs 1,053,228

> 1 wts & > 1 hts recorded in FY2002 844,066 

(80.1%)

> 1 wts in FY2002 & > 1 hts in FY2003-FY2006 89,018 

(8.5%) 

sufficient ht & wt data to calculate BMI 933,084 

(88.6%)
RESEARCHERS’ GUIDE TO VA DATA

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Limitations of Data: 

Impact on Cohort Identification

Due to extreme BMI values, modified plan to id 

obese cohort:

Weights

– divided baseline FY into quarters

– calculated median weight for each quarter 

Heights

– used modal ht FY2002-FY2006

– for patients with > 2 or more modal hts, 

averaged if difference btw modes was < 3 ins 

Baseline BMI

– Used median of median wts for FY2002 & modal 

ht FY2002-2006
RESEARCHERS’ GUIDE TO VA DATA

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Limitations of Data: 

Impact on Outcome Assessment

Original plan: 

BMIs across 5-year study period

- BMI based upon average quarterly wt for 

each of 20 quarters

Modified plan:

BMIs across 5 year study period

– BMI based upon median quarterly wt for each of 

20 quarters

– same modal ht (from FY2002-FY2006) applied 

across 5 years 
RESEARCHERS’ GUIDE TO VA DATA

Blood Pressure Data

Unable to identify any publications using 

CDW BP data

Kerr et al J Qual Improv 2002; 28:555-

565 used BP values from VA Ann Arbor 

from VistA

Valid values for QUERI-DM: 

– 75 <= systolic <=250 

– 25 <= diastolic <=180 

– Usually use last value in period
RESEARCHERS’ GUIDE TO VA DATA

Late-life Patients with Schizophrenia

Of 2.5M records for BP from FY02-FY05, representing 36,876 

unique patients [IIR-05-326]:

14,000 w/o valid numeric data for both diastolic and 

systolic pressures

0.7% had extreme non-missing values

– systolic 0-39 (n=9,081), systolic 0-75 (n=12,956)

– diastolic 0-10 (n=13,396), diastolic 0-25 (n=14,070)

Very low values were primarily 0

– Systolic : n=8,927 of 12,956; diastolic: n=13183 of 14070

Few high values (n=119 sys 250-299, n=13 dias 180-299)

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RESEARCHERS’ GUIDE TO VA DATA

Late-life Patients with Schizophrenia

the cohort originally matched to CDW : N=39,226

the cohort with valid BP & location in CDW: N=33,271

LOCATION:

70% of readings from inpatient encounters

30% of readings from outpatient encounters 

– (6% were missing location)

11,606 inpatients with valid location + valid BP

32,069 outpatients with valid location + valid BP

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RESEARCHERS’ GUIDE TO VA DATA

Case Study: Blood Pressure Data

Is htn an indep pred of survival among black and white pts with schiz?

Depends on what you look at. 

Average measures generally protective or ns (inverse association)

Maxima were positively associated with relative odds of death

Minima were inversely associated with relative odds of death

Effect OR 95% Wald CI

Black 0.73 0.68 - 0.78

Female 0.59 0.49 - 0.70

age10 2.09 2.03 - 2.15

Max OP Sys x10 1.03 1.02 - 1.04

... in another model--

Min IP Dias x10 0.79 0.76 - 0.82

... in another model--

Avg OP Dias x10 0.86 0.82 - 0.90

NOTE: PROC LOGISTIC is modeling the probability that died=1 (n=34094)

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RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in CDW vitals 

data 

Evaluations of CDW data

Case study: CDW anthropometric data

Case study: Blood pressure data

Recommendations

Where to Go for More Help

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RESEARCHERS’ GUIDE TO VA DATA

Recommendations

Consider pros & cons of using repository of 

data derived from routine clinical encounters 

Strategies may be helpful for controlling or 

minimizing impact of error - impossible to 

eliminate all 

“Missing” data may limit usefulness of CDW 

for certain types of questions or patient 

populations

Incumbent upon researchers to be aware of 

limitations of data & potential impact on 

findings
RESEARCHERS’ GUIDE TO VA DATA

Recommendations

Carefully examine each data file supplied by 

any repository

Do number of records and values make 

clinical sense? 

Are there unusual variations over time or by 

facility?

Many measures to choose from – consider 

clinical implications of each
RESEARCHERS’ GUIDE TO VA DATA

Recommendations

Approaches for dealing with error or “missing” 

data may vary depending upon clinical 

population or research question

Select range filters that make sense for 

particular patient population

Delete same day measurements or inpatient 

measurements?

Is measure needed for specific time frame 

and/or are repeated measurements needed 

over time?
RESEARCHERS’ GUIDE TO VA DATA

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Suggestions When Requesting CDW Data

Programming Issues

– SQL view is simplest option for transferring (if SQL 

programmer on study team)

– Be specific in request & re-iterate specifications if 

time passes or CDW programmer changes

– Research programmer may require guidance on 

which cases to throw out or how to summarize 

multiple values in meaningful way

Other Issues

– Because of the size of these files, assess server 

space needs in advance of receipt of data; how 

many copies in what formats will you need to 

create?
RESEARCHERS’ GUIDE TO VA DATA

How to Acquire CDW Extracts

The NDS website 

(http://vaww4.va.gov/NDS/DataAccess/Researchers/RESCDW.asp) 

describes these 3 methods for accessing CDW data:

Data used on CDW Platform –access forms include Form 9957, Privacy 

and DSS Non-Disclosure if required, CDW Rules of Behavior

Data used in VINCI –access forms, VINCI Rules of Behavior

Data delivered as an extract for use on local Research VA secure 

servers –access forms, CDW Rules of Behavior

– NDS expects the PI to control the data locally and track who has access 

to the data. If research staff will assist in obtaining the extract by 

downloading or file transfer from the CDW platform, these individuals will 

need to complete the access forms and sign CDW Rules of Behavior.

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RESEARCHERS’ GUIDE TO VA DATA

References for Further Info

Noël PH, Copeland LA, Pugh MJ, Kahwati L, Tsevat J, 

Nelson K, Wang CP, Bollinger M, Hazuda H. Obesity 

Diagnosis and Care Practices in the Veterans Health 

Administration. JGIM 2010;25(6):510-516.

Noël PH, Copeland LA, Perrin RA, Lancaster AE, Pugh 

MJ, Wang CP, Bollinger MJ, Hazuda HP. VHA Corporate 

data warehouse height and weight data: Opportunities 

and challenges for health services research. JRRD. 

2010:47(8):739-750.

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RESEARCHERS’ GUIDE TO VA DATA

Session Outline

Overview of CDW

Possible sources of error in vitals data 

Evaluations of CDW data

Case study: CDW anthropometric data

Case study: CDW blood pressure data

Recommendations

Where to Go for More Help

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RESEARCHERS’ GUIDE TO VA DATA

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Current Research Data Request 

Process to Access/Obtain Data from 

CDW

Contact CDW to confirm data availability

Request access through VHA National 

Data Systems / DART

– http://vaww4.va.gov/NDS/DataAccess/Researc

hers/RESCDW.asp

– Contact Irma McCaffrey 

(Irma.McCaffrey@va.gov)

– Process involves a review by the VHA 

Privacy Office
RESEARCHERS’ GUIDE TO VA DATA

Current Research Data Request 

Process

Once approved by VHA

– Arrange data set creation with CDW team

– Establish Data Transfer Agreement (DTA) 

with CDW team

• File format (e.g. SQL, .txt)

Is direct access to CDW possible? No.

Secure transfer of data 

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RESEARCHERS’ GUIDE TO VA DATA

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VIReC Help

VIReC Webpage

http://vaww.virec.research.va.gov/

http://www.virec.research.va.gov

– Information on VA data sources and how to 

access data

– Documentation on some VA datasets 

CDW Meta-data Webpage

http://vhacdwa09.vha.med.va.gov:8080/
RESEARCHERS’ GUIDE TO VA DATA

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VIReC Help (cont’d)

HSRData Listserv

– Join at the VIReC Web site

– http://vaww.virec.research.va.gov/Support/HSR

Data-L_Listserv.htm

– Discussion among >500 data stewards, 

managers, and users

– Past messages in archive (on intranet)

VIReC Help Desk

– VIReC staff will answer your question and/or 

direct you to available resources on topics

– VIReC@va.gov

– (708) 202-2413 [8:00am to 4:30pm CST]
RESEARCHERS’ GUIDE TO VA DATA

Questions?

Polly.Noel@va.gov

Laurel.Copeland@va.gov

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