1

Mental Health Data from the NAMCS and NHAMCS

Susan M. Schappert, M.A.Ambulatory and Hospital Care Statistics Branch

Division of Health Care Statistics

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESCenters for Disease Control and PreventionNational Center for Health Statistics

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESCenters for Disease Control and PreventionNational Center for Health Statistics

2

Topics To Be Covered

• Survey Overview

• Data Collected

• Published Mental Health Research Using Data from NAMCS and NHAMCS

• User Considerations

• How to Get the Data

3

An Overview of NAMCS and NHAMCS

4

NAMCS and NHAMCS

• National Ambulatory Medical Care Survey (NAMCS)– Visits to office-based physicians

• National Hospital Ambulatory Medical Care Survey (NHAMCS)– Visits to hospital emergency

and outpatient departments (EDs and OPDs)

5

History of NAMCS

• Planning began in 1967

• Inaugurated in 1973

• Fielded 1973-1981, 1985, 1989-present

• Database covering more than 30 years

6

History of NHAMCS

• Planning began in 1976

• Inaugurated December 1991

• Fielded annually

• 17th year of operation

7

NAMCS Sample Design• Three stage design

– 112 primary sampling units (counties/groups of counties)

– Physician practices within PSUs– Patient visits within practices

• About 3,000 physicians are selected• Each physician is randomly assigned to a

1-week reporting period • Data obtained for 25,000-30,000 patient visits• Sample data must be weighted to produce

national estimates

8

Scope of the NAMCS

• Basic unit of sampling is the physician-patient visit

• In scope visits:– Must occur in physician’s office– Must be for medical purposes– Administrative visits not sampled– House calls, emails, phone calls not

sampled

9

Scope of the NAMCS

• Physicians must be:– Classified by AMA or AOA as primarily

engaged in office-based patient care– nonfederally employed;– not in anesthesiology, radiology, or

pathology – 59 percent response rate in 2006

10

Physicians Sampled in the NAMCS• Physicians are typically stratified into 15 specialty

groups– general and family practice, internal medicine, pediatrics,

ob-gyn, general surgery, orthopedic surgery, cardiovascular diseases, dermatology, urology, psychiatry, neurology, ophthalmology, otolaryngology, and an “other” category

– 2006 included an additional sample of oncologists, and a sample of community health centers

– 29,392 Patient Record Forms completed by about 1,400 physicians in 2006

– 570+ primary care physicians (general and family practice, internal medicine, pediatrics, and ob-gyn) responded in 2006 with data on about 14,400 visits (nearly half of total visit records)

– 80+ psychiatrists reported on nearly 1,400 visits (4.7% of total)

11

In-Scope NAMCS Locations

• Freestanding clinic/urgicenter• Federally qualified health center• Neighborhood and mental health centers• Non-federal government clinic• Family planning clinic• Health maintenance organization• Faculty practice plan• Private solo or group practice

12

Out-of-Scope NAMCS Locations

• Hospital ED’s and OPD’s

• Ambulatory surgicenter

• Institutional setting (schools, prisons)

• Industrial outpatient facility

• Federal Government operated clinic

• Laser vision surgery

13

NHAMCS Sample Design

• Multistage probability design• First stage sample of 112 PSUs• Hospitals within PSUs• Clinics within OPDs, ESA (emergency service

area) within EDs• Patient visits within clinics, ESAs• 4-week reporting period• 486 hospitals sampled in 2006; 35,849 ED visits

and 35,105 OPD visits

14

Scope of the NHAMCS

• Basic unit of sampling is patient visit• Emergency and outpatient departments of

noninstitutional general and short-stay hospitals

• Not Federal, military, or Veterans Administration facilities

• Located in 50 states and D.C.

15

Sampled OPD Clinics• 6 clinic types are defined and used for sampling:

general medicine, surgery, pediatrics, ob-gyn, substance abuse, and “other”

• “Other” includes anxiety, behavioral medicine, eating disorders, psychiatry (adult, child, pediatric, geriatric), mental health, mental hygiene, psychopharmacology, and sleep disorders

• Not included: partial hospitalization programs, day hospital programs, psychology, methadone maintenance

16

Data Collected in the NAMCS and NHAMCS

17

Data Collection• U.S. Census Bureau is our field agent• Induction interview to train medical office or

hospital staff on data collection procedures and to obtain data on practice or facility characteristics

• Physician’s office/hospital staff is responsible for completion of Patient Record forms; Census abstracts as a last resort. In 2006, more than one-third of NHAMCS forms and about one-half of NAMCS forms were completed by Census abstraction.

18

Data Collection

• Patient Record Forms (PRFs)– Nearly identical for NAMCS and OPD– Some differences for ED– Redesigned once every 2 years– Copies at our website:

www.cdc.gov/nhcs/namcs.htm

19

Data Items• Patient characteristics

– Age, sex, race, ethnicity• Visit characteristics

– Source of payment, continuity of care, reason for visit, diagnosis, treatment

• Provider characteristics– Physician specialty, hospital ownership,

region and urban-rural status, use of electronic medical records, and much more

• Drug characteristics added in 1980

20

Mental Health Items Collected inNAMCS and NHAMCS-OPD

• Patient’s reason for visit (all survey years)• Physician’s diagnosis (all survey years)• Does patient now have depression? (1991-92, 1995-96, 2005-06)• Cause of injury (1995-2004), verbatim text added (1997-2004)• Diagnostic/screening services ordered or provided

– Mental status exam (1979-81, 1991-92, 1995-96) – Depression screening (2005-06)

• Medication therapy (1980-2006)• Non-medication therapy ordered or provided

– Psychotherapy/therapeutic listening (1973-1981)– Psychotherapy (1985-92, 1995-2006)– Psycho-pharmacotherapy (1997-2000)– Alcohol abuse counseling (1991-92)– Drug abuse counseling (1991-92)– Stress management counseling (1991-92, 1997-2000, 2005-06)– Mental health counseling (1995-2000)– Mental health/stress management counseling (2001-04)– Other mental health counseling (2005-06)

21

Mental Health Items Collected inNHAMCS-ED

• Patient’s reason for visit (all survey years), verbatim text added 2005-06

• Physician’s diagnosis (all survey years)• Does patient now have depression? (1995-96)• Cause of injury (1995-2006), verbatim text added (1997-2006)• Intentional injury? (1997-2006) • Violence-related injury? (1995-96)• Alcohol- or drug-related visit? (1992-96)• Alcohol-related visit? (2001-04)• Adverse drug event (2001-02)• Patient oriented x 3 (2003-06)• Medication therapy (all survey years)

22

Multiple Response Fields

• Up to 3 reasons for visit, causes of injury, physician diagnoses can be reported for each visit (no cause of injury on NAMCS and OPD starting in 2005)

• Up to 8 medications and each medication can have up to 3 therapeutic classes and up to 5 ingredients

• Multiple procedure codes for NAMCS and OPD

23

Coding Systems Used

• Reason for Visit Classification (NCHS)

• ICD-9-CM for diagnoses, causes of injury, and procedures

• Drug Classification System (NCHS)

• Multum Lexicon starting with 2006 data (previously used National Drug Code Directory)

24

Drug Data in NAMCS/ NHAMCS

Respondents may list up to 8 medications (including Rx, or prescription, and OTC, or over-the-counter, medications, immunizations, allergy shots, anesthetics, and dietary supplements) that were ordered, supplied, administered, or continued during the visit.

Each entry is called a drug mention. Visits with one or more drug mentions are called drug visits.

Respondents are asked to report trade names or generic names only (not dosage, administration, or regimen). Cannot link drugs with diagnosis.

25

• NAMCS or NHAMCS drug data can be analyzed – at the visit level (for example, the number

of visits at which a particular drug was prescribed)

– or at the medication level (for example, the number of “mentions” of a particular drug at ambulatory care visits

26

Published Mental Health Research Using Data from NAMCS and

NHAMCS

27

Hot Topics

• See the NAMCS/NHAMCS website for a complete list of publications (including journal articles) by NCHS and others that use our data (about 100 focus on mental health) – updated monthly

• Mental health research using NAMCS/NHAMCS data includes:– visits for specific diagnoses (depression, ADHD [attention

deficit/hyperactivity disorder], and sleep disorders have been most commonly published, but there are also studies on visits for anxiety disorders, bipolar disorder, autism, schizophrenia)

– pharmacotherapy (antidepressants, antipsychotics, hypnotics, stimulants, psychotropics in general)

– mental health care by physicians other than psychiatrists– racial/ethnic/gender disparities in mental health care– other topics such as self-harm (ED visits), insurance issues,

substance abuse

28

Additional Mental Health Data from NAMCS and NHAMCS

• Many annual NCHS summary reports (for example, Health US) include mental health related data, such as trends in prescribing antidepressants

• Annual NAMCS and NHAMCS summary reports can include various mental health-related statistics (for example, statistics on visits to psychiatrists within tables by physician specialty)

• Some NCHS reports have focused specifically on visits to psychiatrists, alcohol/drug related visits, etc.

29

User Considerations

30

A few things to keep in mind…

• NAMCS/NHAMCS sample visits, not patients• No estimates of incidence or prevalence• No state-level estimates• We do not sample by setting or by non-

physician providers with one exception:– Note that, from 2006, NAMCS includes a stratum of

CHCs (community health centers), and non-physician providers are sampled within CHCs

• May capture different types of care for solo vs. group practice physicians

• May not have much data in a single year for less common conditions or events

31

NAMCS vs. NHAMCS

• Consider what types of settings are best for a particular analysis– Persons of color are more likely to visit OPDs

and EDs than physician offices– Persons in some age groups make

disproportionately larger shares of visits to EDs than offices and OPDs

32

Ways to Improve Reliability of Estimates

• Combine NAMCS, ED, and OPD data to produce ambulatory care visit estimates

• Combine multiple years of data

• Aggregate categories of interest into broader groups.

33

Caveat on Counseling Services

• Diagnostic services are reflected accurately on medical records, but counseling services may not be

• NAMCS (and OPD) data may underestimate the amount of health habit counseling that occurs if it is not documented in the medical record

• These findings were published by in the following article: Gilchrist VJ, Stange KC, Flocke SA, McCord G, Bourguet CC. A Comparison of the National Ambulatory Medical Care Survey (NAMCS) Measurement Approach With Direct Observation of Outpatient Visits. Medical Care 42(3), March 2004, 276-280.

34

How To Get the Data

35

http://www.cdc.gov/nchs/namcs.htmhttp://www.cdc.gov/nchs/namcs.htm

36

Public Use Micro-data Files

• Downloadable files• NAMCS, 1973-2006• NHAMCS, 1992-2006

• CD-ROMs• NAMCS, 1990-2005• NHAMCS, 1992-2005

37

Enhanced Public Use Files

• SAS input statements, label statements, and format statements (1993-2006)

• SPSS and Stata code for 2002-2006

• Masked sample design variables– Allow use of SUDAAN, Stata, etc.– Available for 1993-2006

38

NCHS Research Data Center

39

Advantages of the NCHSResearch Data Center

• Users gain access to information not available on public use files– Patient: ZIP code-linked income, education,

poverty status, percent foreign born, percent not speaking English well, urban-rural classification

– Provider: physician sex, age, and board certification, teaching hospital

– Geographic: FIPS (Federal Information Processing Standard) state and county codes

– Special files and data supplements– For a complete list of variables, contact the

Ambulatory and Hospital Care Statistics Branch

40

Research Data Center – cont.

• Can merge with contextual variables (e.g., Area Resource File, National Health Interview Survey, National Hospital Discharge Survey Census)– Health status level– Health Maintenance Organization (HMO)

penetration– Physician and specialist supply– Medicaid reimbursement– Air quality– Percent in poverty

41

Research Data Center Procedures

• Submit a proposal• May not use data to identify patients or

providers or geographic location of providers

• May not remove data files• Fees vary based on whether use is

onsite or remote and whether project requires file construction by NCHS staff

42

Research Data Center

• E-mail: rdca@cdc.gov

• Website: www.cdc.gov/nchs/r&d/rdc.htm

• Call (301) 458-4277

43

Additional Information

• Call the Ambulatory and Hospital Care Statistics Branch at (301) 458-4600

• Visit our website at www.cdc.gov/nhcs/namcs.htm

• Join the ACLIST. It’s a moderated newsgroup for persons interested in NAMCS/NHAMCS. It currently consists of about 2,600 subscribers.