RESEARCHERS’ GUIDE TO VA DATA

Measuring Outpatient Pharmacy Use 

in the VA Using VA Pharmacy Data

April 1, 2013

Presented by:

Denise M. Hynes, MPH, PhD, RN 

1 

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

Audience Poll

Have you ever used VA Pharmacy Data?

– Yes 

– No

How would you rate your overall 

knowledge of VA Pharmacy Data?

– 1 (Never Used)

– 2 

– 3 

– 4 

– 5 (Used Frequently, Very familiar)

2 
RESEARCHERS’ GUIDE TO VA DATA

Session Objectives

How has outpatient pharmacy utilization 

been measured in VA studies? 

Overview of VA Pharmacy databases

Finding information in the VA Pharmacy 

databases

Examples of VA studies that have used 

the VA Pharmacy databases

Where to go for more help

3 
RESEARCHERS’ GUIDE TO VA DATA

Session Objectives

How has outpatient pharmacy utilization 

been measured in VA studies? 

Overview of VA Pharmacy databases

Finding information in the VA Pharmacy 

databases

Examples of VA studies that have used 

the VA Pharmacy databases

Where to go for more help

4 
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient pharmacy utilization been 

measured in VA studies?: 

Trends in Medication Use

Tarlov E, Stroupe KT, 

et al. Trends in anemia 

management in lung 

and colon cancer 

patients in the US 

Department of 

Veterans Affairs, 

2002-2008. Support 

Care Cancer. 2012;

20:1649–1657

Use of ESA drug over 

time

5 
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient pharmacy utilization been 

measured in VA studies?: 

Medication Exposure and Outcomes

Pugh MJV, Copeland LA, 

Zeber JE, et al. 

Antiepileptic drug 

monotherapy exposure 

and suicide-related 

behavior in older Veterans. 

J Am Geriatr Soc. 2012 

Nov;60(11):2042-7.

Association of a specific 

drug with potential 

adverse event

6 
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient healthcare utilization been 

measured in VA studies?: 

Medication Adherence

7 

Huetsch JC, Uman JE, Udris 

EM, Au DH. Predictors of 

Adherence to Inhaled 

Medications Among Veterans 

with COPD. J Gen Intern Med.

2010; 27(11):1506–12

Examined adherence using 

info from medication refill 

pattern data
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient pharmacy utilization been 

measured in VA studies?: 

Medication Use

Gellad WF, Aspinall SL, 

Handler SM, Stone RA, 

Castle N, Semla TP, Good 

CB, Fine MJ, Dysken M, 

Hanlon JT. Use of 

Antipsychotics Among 

Older Residents in VA 

Nursing Homes. Med Care. 

2012;50: 954–960.

Identified specific drug 

class use in nursing 

home patients 

8 
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient healthcare utilization been 

measured in VA studies?: 

Cohort Identification

9 

Ng B, Aslam F, Petersen NJ, Yu 

HJ, Suarez-Almazor ME. 

Identification of Rheumatoid 

Arthritis Patients Using an 

Administrative Database: A 

Veterans Affairs Study. 

Arthritis Care & Research. 

2012; 64:1490–1496.

Used a specific drug type to 

improve case identification
RESEARCHERS’ GUIDE TO VA DATA

Session Objectives

How has outpatient pharmacy utilization 

been measured in VA studies? 

Overview of VA Pharmacy databases

Finding information in the VA Pharmacy 

databases

Examples of VA studies that have used 

the VA Pharmacy databases

Where to go for more help

10
RESEARCHERS’ GUIDE TO VA DATA

Pharmacy Data Sources

Local Databases

– VistA

– VISN Warehouses 

National Data Sources

– PBM

– DSS NDE Pharmacy SASR Datasets

– Corporate Data Warehouse

11
RESEARCHERS’ GUIDE TO VA DATA

Pharmacy Data Sources

Other Key Pharmacy Data Sources

– DSS Product Table

– National Drug File

12
RESEARCHERS’ GUIDE TO VA DATA

Audience Poll

Which national sources of VA pharmacy 

data have you used in the past?

– DSS NDE Pharmacy Data

– PBM Pharmacy Data

– Both

– Neither

13
RESEARCHERS’ GUIDE TO VA DATA

VA Pharmacy Data Sources

VA Decision Support System (DSS) 

National Data Extract (NDE) Pharmacy SAS 

Datasets

– Became available in 2003

– Data from FY2002 to present

– Primary source of data is VistA

– All inpatient and outpatient prescriptions 

dispensed by a VAMC or VA Consolidated Mail 

Outpatient Pharmacy (CMOP)

– Housed at Austin Information Technology Center 

(AITC) and directly accessible

14
RESEARCHERS’ GUIDE TO VA DATA

VA Pharmacy Data Sources

VA Pharmacy Benefits Management (PBM) 

Database

– Available since 2000

– Data from FY1999 to present

– Primary source of data is VistA

– Contains both inpatient and outpatient 

prescriptions 

15
RESEARCHERS’ GUIDE TO VA DATA

PBM vs. DSS

PBM DSS

Cost Drug supply cost Actual cost (ACT_COST)

Dispensing cost (DISPCOST)

Supply cost (VS_COST) 

Access Researcher requested extract Direct access

Data availability FY1999 (Outpatient) FY2002 (Outpatient & Inpatient) 

FY2004 (Inpatient)

Directions for SIG available (also 

use components of SIG available: 

SCHED, UNT_DOSE, 

DSP_UNT) 

16
RESEARCHERS’ GUIDE TO VA DATA

Key Pharmacy Variables

Variable DSS PBM

Days Supply X X 

Drug Description X X 

Quantity X X 

NDC X X 

Medication class X X 

17
RESEARCHERS’ GUIDE TO VA DATA

Other DSS and PBM Pharmacy Data

DSS Product Table

– Key Variables

• IPNum, Feeder Key, Description (short and long), 

Drug Class

• Feeder Key => 1st 5 characters are VA product 

file IEN; last 12 characters are NDC

– Available on DSS website

National Drug File

– Key Variables

• VA_PRODUCT, FEEDER, NDF_NDC, VA_CLASS

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RESEARCHERS’ GUIDE TO VA DATA

Other CDW Pharmacy Data

Key Product Tables

– Pharmacy BCMA

• Dispensed Drug, Medication Log, Medication 

Variance + Missing Dose Request

– Pharmacy Outpatient

• RxOutPat Prescriptions, RxOutPat Fill, RxOutPat 

Sig, RxOutPat Med Instructions

19
RESEARCHERS’ GUIDE TO VA DATA

20

Session Objectives

How has outpatient pharmacy utilization 

been measured in VA studies? 

Overview of VA Pharmacy databases

Finding information in the VA Pharmacy 

databases

Examples of VA studies that have used 

the VA Pharmacy databases

Where to go for more help
RESEARCHERS’ GUIDE TO VA DATA

Assessing Outpatient Pharmacy Use:

Finding info in VA Pharmacy Datasets

Where can I find cost variables?

DSS and PBM contain different cost variables

– PBM: cost of the drug product from the supplier

– DSS: 

1) Dispensing Cost (DISPCOST): direct pharmacist 

labor for dispensing the prescription and the 

mailing costs

2) Supply Cost (VS_COST): Drug product cost and 

cost of supplies used in preparing the prescription, 

such as bottles and labels

3) Actual Cost (ACT_COST): Drug product cost, cost 

of supplies such as bottles and labels to prepare 

the prescription, indirect costs, and overhead

21
RESEARCHERS’ GUIDE TO VA DATA

22

Assessing Outpatient Pharmacy Use:

Finding info in VA Pharmacy Datasets

Why is the NDC for the same prescription 

different on the PBM record than on the 

DSS record?

The NDC’s are obtained from different sources

Differences can result if Local Drug File has not been 

updated to reflect supply that was stocked when 

medication was dispensed

Different NDC’s will refer to the same drug, 

 dosage, and strength, but may indicate a 

different manufacturer and/or package size
RESEARCHERS’ GUIDE TO VA DATA

23

Session Objectives

How has outpatient pharmacy utilization 

been measured in VA studies? 

Overview of VA Pharmacy databases

Finding information in the VA Pharmacy 

databases

Examples of VA studies that have used 

the VA Pharmacy databases

Where to go for more help
RESEARCHERS’ GUIDE TO VA DATA

Assessing Outpatient Pharmacy Use:

Examples of Types of Questions Addressed with Pharmacy 

Data 

Cohort identification 

– Can pharmacy data be used to identify specific groups of 

patients? 

Medication utilization 

– Recent year? Longer historical view? Does policy change 

impact medication use?

Healthcare quality 

– Are patients being prescribed medications in accordance with 

quality measures?

Medication adherence

– How much of a prescribed medication are patients using?

Exposure to specific medications or medication 

classes – Are specific drugs associated with better/worse outcomes?

Combining outpatient and pharmacy data to identify 

events

– Can we identify acute exacerbations of COPD with outpatient 

and prescription data?

Assessing comorbidity or case-mix with medication 

data

24
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient pharmacy utilization been 

measured in VA studies?: 

Medication Exposure and Outcomes

Pugh MJV, Copeland LA, 

Zeber JE, et al. Antiepileptic 

drug monotherapy exposure 

and suicide-related behavior 

in older Veterans. J Am 

Geriatr Soc. 2012; 

60(11):2042-7.

Objective: To examine the 

association between 

antiepileptic drug (AED) 

receipt and suicide-related 

behavior (SRB) in older 

veterans

25
RESEARCHERS’ GUIDE TO VA DATA

Medication Exposure and Outcomes: 

Pugh et al. J Am Geriatr Soc. 2012

January 2008, FDA released alert claiming twice risk of suiciderelated behavior in patients taking antiepileptic drugs (AEDs)

– Elderly patients were under-represented in FDA analysis

This study compares suicide-related behavior in older Veterans 

with and without AEDs

– Cohort of patients age 65 years

Drugs were identified according to the generic name using VHA 

product variable

How was pharmacy data used?

– Cox proportional hazards models used to compare time to event (suiciderelated behavior) for patients with or without AED exposure

26
RESEARCHERS’ GUIDE TO VA DATA

Medication Exposure and Outcomes: 

Pugh et al. J Am Geriatr Soc. 2012

Study timeline

27

•12 months of prior VHA use

•12 months without AED

12 month follow-up period

For Veterans 65 or older between FY04-06, 

Incident Exposure was: 

• Initial AED (Veterans with AED) 

• First VHA use (Veterans without AED) 

Follow-up Measure:

• Suicide-related behavior
RESEARCHERS’ GUIDE TO VA DATA

Medication Exposure and Outcomes: 

Pugh et al. J Am Geriatr Soc. 2012

28 Adapted from Pugh et al J Am 

Geriatr Soc. 2012

AED exposure:

90,263 (4.2%)

No AED Exposure:

2,056,911 (95.8%)
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient healthcare utilization been 

measured in VA studies?: 

Medication Adherence

29

Huetsch JC, Uman JE, Udris 

EM, Au DH. Predictors of 

Adherence to Inhaled 

Medications Among Veterans 

with COPD. J Gen Intern Med. 

2010; 27(11):1506–12

Objective: To assess predictors 

of adherence to inhaled therapies 

for COPD and, for patients on 

multiple inhaled medications, to 

assess whether adherence to one 

class of medication predicts 

adherence to other classes 
RESEARCHERS’ GUIDE TO VA DATA

Medication Adherence:

Huetsch et al. J Gen Intern Med. 2012

Cohort consisted of patients with pulmonary 

function tests between January 2004 and 

December 2007 who 

– Had spirometric evidence of COPD 

– Had a ReComp (medication adherence) measure for one or 

more COPD medications

Medicare adherence assessed for 3 drug classes:

– inhaled corticosteroids (ICS)

– ipratropium bromide (IP)

– long-acting beta-agonists (LABA) 

ReComp used to measure adherence

30
RESEARCHERS’ GUIDE TO VA DATA

Medication Adherence:

Huetsch et al. J Gen Intern Med. 2012

ReComp is an algorithm to measure medication 

adherence

– 1 indicates medication available to patient during all days 

during period of interest

– 0 indicates no medication available to patient during period 

of interest

For Outcome Adherence

– ReComp > 0.8 was considered adherent

For Baseline Adherence

– Poor (score: 0 to <0.20)

– Moderate (score: ≥0.20 to <0.80)

– Good (score: ≥0.80 to <1.0)

– Excellent (score: 1.0).

31
RESEARCHERS’ GUIDE TO VA DATA

Medication Adherence:

Huetsch et al. J Gen Intern Med. 2012

How was pharmacy data used?

32

Baseline Adherence:

• ReComp 6 months before enrollment

6 month follow-up period

Cohort Enrollment

Outcome Adherence: 

• ReComp 6 months after enrollment
RESEARCHERS’ GUIDE TO VA DATA

Medication Adherence:

Huetsch et al. J Gen Intern Med. 2012

Adapted from Huetsch et al. 33

J Gen Intern Med. 2012
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient pharmacy utilization been 

measured in VA studies?: 

Medication Use

Gellad WF, Aspinall SL, 

Handler SM, Stone RA, 

Castle N, Semla TP, Good 

CB, Fine MJ, Dysken M, 

Hanlon JT. Use of 

Antipsychotics Among 

Older Residents in VA 

Nursing Homes. Med Care. 

2012;50: 954–960. 

Objective: To assess the 

prevalence and risk factors 

for antipsychotic use in 

older residents of VA 

Community Living Centers 

34
RESEARCHERS’ GUIDE TO VA DATA

Medication Use:

Gellad et al. Med Care. 2012

Antipsychotic medications are commonly 

prescribed to nursing home residents 

despite well-established adverse events

Cohort consisted of all residents of VA 

Community Living Center between 

1/1/2004 and 6/30/2005 with at least 

VA Rx dispensing

Logistic regression used to indentify 

factors associated with antipsychotic use

35
RESEARCHERS’ GUIDE TO VA DATA

Medication Use:

Gellad et al. Med Care. 2012

How was pharmacy data used?

Pharmacy data from PBM was linked with 

Minimum Data Sets (MDS) and MedSAS data

For each dispensed drug, study collected

– Start and stop date

– Medication name

– Medication strength

– Directions for use (i.e., SIG)

– Amount dispensed

To create a polypharmacy covariate for 

regression, identified the number of unique 

drugs per resident 36
RESEARCHERS’ GUIDE TO VA DATA

Medication Use:

Gellad et al. Med Care. 2012

Resident classified based on whether there were 

indications for antipsychotic medications

– Appropriate use included patients with psychiatric 

diagnosis in which psychotic symptoms are prominent 

feature or a diagnosis of dementia and psychotic 

symptoms 

– Potentially inappropriate use were remaining patients 

without psychiatric diagnosis or psychotic symptoms

• With dementia

• Without dementia

37
RESEARCHERS’ GUIDE TO VA DATA

Medication Use:

Gellad et al. Med Care. 2012

Adapted from Gellad et al. 38

Med Care. 2012
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient pharmacy utilization been 

measured in VA studies?: 

Trends in Medication Use

Tarlov E, Stroupe KT, et al. 

Trends in anemia 

management in lung and 

colon cancer patients in the 

US Department of Veterans 

Affairs, 2002-2008. Support 

Care Cancer. 2012;

20:1649–1657

Objective: To examine 

erythropoiesis-stimulating 

agent (ESA) therapy in lung 

and colon cancer patients 

receiving chemotherapy 

from 2002 to 2008

39
RESEARCHERS’ GUIDE TO VA DATA

40

Trends in Medication Use:

Tarlov et al. Support Care Cancer. 2012

How was pharmacy data used?

Pharmacy data was use to examine:

– Whether ESA use differed before (PRE) or after (POST) the black box 

warning

– Trends in ESA use over time 

1/1/07

Study Timeline FDA Issues Black Box Warning, 3/2007

POST Period

PRE Period

12/31/09

1/1/02
RESEARCHERS’ GUIDE TO VA DATA

Trends in Medication Use:

Tarlov et al. Support Care Cancer. 2012

For lung cancer patients

Odds of ESA use decreased 65% in the POST period

For colon cancer patients

Odds of ESA use decreased 53% in the POST period

Adapted from Tarlov et al

Support Care Cancer. 2012 41
RESEARCHERS’ GUIDE TO VA DATA

Trends in Medication Use:

Tarlov et al. Support Care Cancer. 2012

ESA use began to decline for both cancer groups before black 

box warning was issued

0 .05 .1 .15 .2 .25 .3 .35 .4 .45

Probability

2002 2003 2004 2005 2006 2007 2008

Colon (N=4,225)

Lung (N=17,014)

Diagnosis Year

March 2007: FDA “black box” warning

Adapted from Pugh et al J Am 

Geriatr Soc. 2012 42
RESEARCHERS’ GUIDE TO VA DATA

How has outpatient healthcare utilization been 

measured in VA studies?: Cohort Identification

43

Ng B, Aslam F, Petersen NJ, Yu 

HJ, Suarez-Almazor ME. 

Identification of Rheumatoid 

Arthritis Patients Using an 

Administrative Database: A 

Veterans Affairs Study. 

Arthritis Care Research. 2012; 

64:1490–1496. 

Objective: To assess the utility 

of diagnostic algorithms, 

including prescriptions, to 

identify RA patients within VHA 

databases
RESEARCHERS’ GUIDE TO VA DATA

Cohort Identification:

Ng et al. Arthritis Care Research. 2012

Study sample consisted of patients having 2 

outpatient visits with rheumatoid arthritis 

(RA) codes at least 2 months apart at Houston 

VAMC between FY99 and FY09

How was pharmacy data used?

Study tested algorithms to identify RA in 

through VHA databases using

– Presence of at least 2 ICD-9 at least 6 months apart

– Use of disease-modifying antirheumatic drugs 

(DMARD) for at least 180 days

– ICD-9 code for RA at visit to rheumatologist

44
RESEARCHERS’ GUIDE TO VA DATA

Cohort Identification:

Ng et al. Arthritis Care Research. 2012

Study design

– To validate diagnosis of RA, study conducted chart 

review 

– Study evaluated the positive predictive value (PPV) of 

the diagnostic algorithms using validation from chart 

review 

45
RESEARCHERS’ GUIDE TO VA DATA

Cohort Identification:

Ng et al. Arthritis Care Research. 2012

Adapted from Ng et al. Arthritis 46

Care Research. 2012

Adding DMARD therapy to the patient identification algorithm 

increased the PPV

Highest PPV (91.4%) was found in patients who:

Received DMARDs for at least 180 days

Had an RA code from visit to rheumatologist
RESEARCHERS’ GUIDE TO VA DATA

47

Session Objectives

How has outpatient pharmacy utilization 

been measured in VA studies?

Overview of VA Pharmacy databases

Finding information in the VA Pharmacy 

databases

Examples of VA studies that have used 

the VA Pharmacy databases

Where to go for more help
RESEARCHERS’ GUIDE TO VA DATA

48

VIReC Help

VIReC Webpage

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

– Information on VA data sources and how to 

access data

– Resource users guide for pharmacy data

• http://www.virec.research.va.gov/References/RUG/

RUG-Pharmacy-2nd-Ed-er.pdf
RESEARCHERS’ GUIDE TO VA DATA

49

VIReC Help (cont’d)

HSRData Listserv

– Join at the VIReC Web site

– Discussion among >400 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
RESEARCHERS’ GUIDE TO VA DATA

50

Questions?
RESEARCHERS’ GUIDE TO VA DATA

Selected Recent References on 

VA Outpatient Pharmacy Use

Berlowitz, D. R. & Pugh, M. J. (2007). Pharmacoepidemiology in community- dwelling elderly taking antiepileptic drugs. Int Rev Neurobiol., 81:153-63.,

153-163.

Damush, T. M., Jia, H., Ried, L. D., Qin, H., Cameon, R., Plue, L. et al. (2008). 

Case-finding algorithm for post-stroke depression in the veterans health administration. Int J Geriatr Psychiatry., 23, 517-522.

Davis, R. G., Hepfinger, C. A., Sauer, K. A., & Wilhardt, M. S. (2007). 

Retrospective evaluation of medication appropriateness and clinical 

pharmacist drug therapy recommendations for home-based primary care 

veterans. Am J Geriatr Pharmacother., 5, 40-47.

Frayne, S. M., Yu, W., Yano, E. M., Ananth, L., Iqbal, S., Thrailkill, A. et al. 

(2007). Gender and use of care: planning for tomorrow's Veterans Health 

Administration. J Womens Health (Larchmt.)., 16, 1188-1199.

Gellad WF, Aspinall SL, Handler SM, Stone RA, Castle N, Semla TP, Good CB, 

Fine MJ, Dysken M, Hanlon JT. Use of Antipsychotics Among Older Residents 

in VA Nursing Homes. Med Care. 2012;50: 954–960. 

Huetsch JC, Uman JE, Udris EM, Au DH. Predictors of Adherence to Inhaled 

Medications Among Veterans with COPD. J Gen Intern Med. 2010; 

27(11):1506–12.

Iqbal, S. U., Cunningham, F., Lee, A., Wang, S., Hamed, A., Miller, D. R. et al. 

(2007). Divalproex sodium vs. valproic acid: drug utilization patterns, 

persistence rates and predictors of hospitalization among VA patients 

diagnosed with bipolar disorder. J Clin Pharm Ther., 32, 625-632.

51
RESEARCHERS’ GUIDE TO VA DATA

Selected Recent References on 

VA Outpatient Pharmacy Use (cont)

Jia, H., Damush, T. M., Qin, H., Ried, L. D., Wang, X., Young, L. J. et al. 

(2006). The impact of poststroke depression on healthcare use by 

veterans with acute stroke. Stroke., 37, 2796-2801.

Lee, T. A., Pickard, A. S., Au, D. H., Bartle, B., & Weiss, K. B. (2008). Risk 

for death associated with medications for recently diagnosed chronic 

obstructive pulmonary disease. Ann Intern Med., 149, 380-390.

Mahmood, M., Malone, D. C., Skrepnek, G. H., Abarca, J., Armstrong, E. 

P., Murphy, J. E. et al. (2007). Potential drug-drug interactions within 

Veterans Affairs medical centers. Am J Health Syst Pharm., 64, 1500-

1505.

Mortensen, E. M., Restrepo, M. I., Copeland, L. A., Pugh, J. A., Anzueto, 

A., Cornell, J. E. et al. (2007). Impact of previous statin and angiotensin 

II receptor blocker use on mortality in patients hospitalized with sepsis. 

Pharmacotherapy., 27, 1619-1626.

Ng B, Aslam F, Petersen NJ, Yu HJ, Suarez-Almazor ME. Identification of 

Rheumatoid Arthritis Patients Using an Administrative Database: A 

Veterans Affairs Study. Arthritis Care & Research. 2012; 64:1490–1496.

Poon, I. O., Lal, L., Brown, E. N., & Braun, U. K. (2007). The impact of 

pharmacist-managed oral anticoagulation therapy in older veterans. J 

Clin Pharm Ther., 32, 21-29.

52
RESEARCHERS’ GUIDE TO VA DATA

Selected Recent References on 

VA Outpatient Pharmacy Use (cont)

Pugh MJV, Copeland LA, Zeber JE, et al. Antiepileptic drug monotherapy 

exposure and suicide-related behavior in older Veterans. J Am Geriatr 

Soc. 2012 Nov;60(11):2042-7.

Sernyak, M. J. & Rosenheck, R. A. (2008). Antipsychotic use in the 

treatment of outpatients with schizophrenia in the VA from fiscal years 

1999 to 2006. Psychiatr Serv., 59, 567-569.

Tarlov E, Stroupe KT, et al. Trends in anemia management in lung and 

colon cancer patients in the US Department of Veterans Affairs, 2002-

2008. Support Care Cancer. 2012; 20:1649–1657 

VIReC Technical Report: Comparison of VA Outpatient Prescriptions in 

the DSS Datasets and the PBM Database

http://vaww.virec.research.va.gov/References/TechnicalReports/VIRe

CTechnicalReport1.pdf. 

Walbrown, M. A., Aspinall, S. L., Bayliss, N. K., Stone, R. A., 

Cunningham, F., Squier, C. L. et al. (2008). Evaluation of Clostridium 

difficile-associated diarrhea with a drug formulary change in preferred 

fluoroquinolones. J Manag Care Pharm., 14, 34-40.

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RESEARCHERS’ GUIDE TO VA DATA

54

Upcoming Seminar

Assessing Race and Ethnicity - May 6, 2013

Maria Mor, PhD