Linda McCaig and David Woodwell

1
Overview of the NAMCSand NHAMCS

• Linda McCaig and David Woodwell
• 2008 NCHS Data Users Conference
• August 12, 2008

2
Overview

• Background
• Data uses
• Survey methodology
• Current and proposed survey items
• User considerations
• Methodological studies
• Data dissemination
• NCHS Research Data Center

3
National probability sample surveys

• National Ambulatory Medical Care Survey (NAMCS)
• Patient visits to non-federal office-based
  physicians
• National Hospital Ambulatory Medical Care Survey
  (NHAMCS)
• Patient visits to EDs and OPDs of non-federal
  short-stay hospitals

4
Original NAMCS survey goals

• National statistics
• Professional education
• Health policy formulation
• Quality assurance

5
NAMCS history

• Survey began in 1973
• Annual data collection through 1981 (NORC)
• Conducted in 1985 (NORC)
• Annual began again in 1989 (Census)

6
NHAMCS history

• Survey began in 1992
• Annual data collection (Census)

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How are NAMCS and NHAMCS data used?

• Changes in utilization and practice
• diagnoses, tests/procedures, prescribing
• Quality of care
• Impact of performance measures and educational
  campaigns
• Healthy People 2010 objectives
• Health disparities
• Adoption/Diffusion of new technologies

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Data users

• Medical associations
• Government agencies
• Institute of Medicine
• Health services researchers
• University and medical schools
• Broadcast and print media

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The IOM report
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Trends in emergency department visits, number of
hospitals, and number of emergency departments in
the United States, 1994-2004

• Kellermann A. N Engl J Med 20063551300-1303

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Number of patients arriving (line) and occupancy
(bars) of EDs by hour of day and admission status
14
Average annual numbers of emergency department
visits and hospital readmissions within 7 days of
a hospital discharge in relation to the number of
hospital discharges with corresponding ratios
United States, 2005-06
719,000
1
Hospital readmission
21
Emergency department visits
2,321,000
68
34,019,000
1000
Hospital inpatient discharges
Note 1Hospital readmissions include admission
to the same hospital as the emergency department
visit or transfer to another hospital. Example of
use For every 1,000 hospital inpatient
discharges, there were 68 emergency department
visits, and 21 hospital readmissions.
15
Percentage of ED visits at which an opioid was
prescribed by pain severity and race
1997-2000
2003-2005
NOTE Pain severity was not collected in
2001-2002. SOURCE Wilper AP et al. Health
Affairs. 2008Jan-Febw84-w93.
16
Ambulatory care visit rates by setting
plt0.05.
17
Ambulatory care antimicrobial prescribing rates
for HP2010 goals
18
Percent of office visits by type of service
ordered or provided by physicians in primary care
specialties in CHCs and physician offices
1 plt0.05.
19
Indicator performance by use of electronic health
records in physician offices

1
Note All comparisons are significant (plt 0.01).
UA is urinalysis. SOURCE Linder JA et al.
Archives of Internal Medicine.
20081671400-1405.
20
Percentage of OPD visits by adults 18 years and
over with selected chronic conditions

• NOTECOPD is chronic obstructive pulmonary
  disease.
• 1 (plt0.05).

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NAMCS and NHAMCS Methodology
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NAMCS Scope

• Includes non-federal, office-based physicians
• Excludes physicians whose main activity is
  teaching, research, administration,
  hospital-based care, or who are unclassified as
  to activity and those in certain specialties

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In-Scope NAMCS locations

• Freestanding clinic/urgicenter
• Community health centers
• Neighborhood and mental health centers
• Non-federal government clinic
• Family planning clinic
• HMO
• Faculty practice plan
• Private solo or group practice

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Out-of-Scope NAMCS locations

• Hospital EDs and OPDs
• Ambulatory surgicenter
• Institutional setting (schools, prisons)
• Industrial outpatient facility
• Federal Government operated clinic
• Laser vision surgery

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NAMCS Sample design

• 112 geographic PSUs
• 3,700 physicians
• 29,000 visits
• 1 week reporting period

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NHAMCS Scope

• OPD was intended to be parallel to the NAMCS in
  the hospital setting
• General medicine, surgery, pediatrics, ob/gyn,
  substance abuse, and other clinics are in-scope
• Ancillary services are out of scope

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NHAMCS Sample design

• 112 geographic PSUs
• 500 hospitals
• 400 EDs and 250 OPDs
• 37,000 ED and 35,000 OPD visits
• 4-week reporting period

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Gaining cooperation

• Advance letters
• Endorsement letters
• Public relations materials
• Conversion of refusal

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Data collection procedures

• Induction visit by Census field representative
  (FR)
• FR training of office/hospital staff
• Take every number
• Prospective or retrospective method

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Items available on the public use file

• Patient characteristics
• age, race, sex, ethnicity
• Visit characteristics
• reason for visit, diagnosis, medication
• Provider characteristics
• physician specialty, hospital ownership
• Contextual variables based on pt zip code
• of poverty, median HH income, adults with
  bachelors degree or higher, urban/rural

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Repeating fields

• Reason for visit (3)
• Diagnosis (3)
• Cause of injury (3) ED only
• Ambulatory surgical procedures (2) OPD and
  NAMCS only
• Medications (8)

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Data processing

• Data are coded and keyed by SRA International
• Quality control procedures
• Edit checks by NCHS

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Coding systems used

• A Reason for Visit Classification (NCHS)
• ICD-9-CM
• diagnoses
• external causes of injury
• procedures
• Drug coding system (NCHS)

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Therapeutic classification system

• 1985-2005, FDAs NDC therapeutic classification
  was used
• Limitations
• Discontinued by FDA
• Only one level of sub-classification

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Therapeutic classification system - Multum Lexicon

• Starting with 2006 data
• Advantages
• Two levels of sub-classification
• Regular updates

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Example Classification of paroxetine

• NDC
• 0600 central nervous system
• 0630 antidepressants
• Multum Lexicon
• 242 psychotherapeutic agents
• 249 antidepressants
• 208 SSRI antidepressants

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2006 NAMCS PRF
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Patient Record form (PRF)

• Common items
• Unique items
• 2007-08 modifications
• 2009-10 proposed changes

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Patient Record form - common items

• Patients zip code
• Date of visit
• Date of birth
• Sex
• Ethnicity

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Patient Record form- common items

• Race
• Source of payment
• Temperature and blood pressure
• Reason for visit
• Diagnosis
• Injury, poisoning, adverse effect

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Patient Record form common items

• Diagnostic/screening services
• Medications and injections
• Providers seen
• Visit disposition

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ED Patient Record form- unique items

• Times arrival, time seen, discharge
• Residence nursing home, homeless
• Mode of arrival
• Vital signs heart rate, pulse oximetry
• Immediacy
• Pain level
• Work-related

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ED Patient Record form- unique items

• Previous care
• Seen in ED in last 72 hours
• Discharged from hospital in last 7 days
• Injury, poisoning, adverse effect
• Cause of injury verbatim text since 1997
• Intentionality
• Procedure checklist

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ED Patient Record form- unique items

• Hospital admission
• type of unit
• time of admission
• date of discharge
• principal hospital discharge diagnosis
• discharge status

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NAMCS and OPD PRF- unique items

• Does patient use tobacco
• Counseling/education/therapy
• Surgical procedures
• Time spent with physician (NAMCS only)

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NAMCS and OPD PRFcontinuity of care items

• Patients primary care physician/provider
• Was patient referred for visit
• Patient seen before
• Seen how many times in past 12 months
• Major reason for visit

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Modifications to 2007-08 ED PRF

• On
• Respiratory rate
• of times seen in ED in last 12 months
• Episode of care
• Hospital admission date
• Hospital discharge disposition

• Off
• Work related visit

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Modifications to 2007-08 NAMCS/OPD PRFs

• On
• None

• Off
• Patient pregnant
• LMP or gestation week

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2009-10 ED PRF- new items

• Dates for all times
• On oxygen on arrival
• Glasgow coma scale (GCS)
• Chronic disease checklist cerebrovascular
  disease, CHF, CRF, HIV, diabetes
• Level of service

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2009-10 ED PRF -new items for admitted and
observation unit patients

• Date and time bed was requested
• Date and time patient left ED
• If admitting physician is a hospitalist
• Date and time of observation unit discharge

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Modifications to 2009-10 NAMCS/OPD PRFs

• On
• None

• Off
• Cancer stages
• Enrollment in a disease management program

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2007-08 NHAMCS induction form- new hospital items

• Inpatient items
• of days in a week elective surgeries are
  scheduled
• bed coordinator/czar
• bed census data

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NHAMCS induction form- new ED items for 2007- 08

• Boarding
• More than 2 hours, inpatient hallways
• Ambulance diversion
• Regional, continue to admit elective surgery
  cases
• Procedures
• bedside registration
• electronic dashboard
• zone nursing

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Which do doctors prefer? Electronic or
handwritten?
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Background on survey of ambulatory surgery
centers (ASCs)

• National Survey of Ambulatory Surgery (NSAS)
• Conducted in 1994-96 and 2006
• Hospital-based and free-standing
• 35 million visits annually (57 hospital-based)
• Difficult to obtain funding for annual NSAS

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Timeline for incorporation of ASC component into
NHAMCS

• Conduct pilot test in August 2008 to test forms
  and sampling procedures for hospital-based ASCs
• Add hospital-based ASCs to 2009 NHAMCS
• Add free-standing ASCs to 2010 NHAMCS

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Overview

• NAMCS scope
• New items on the Physician Induction Interview
  (PII)
• User considerations
• Methodological studies
• HIPAA
• Data dissemination
• NCHS Research Data Center

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2006 NAMCS

• Traditional sample of office-based physicians
• Stratum of 104 Community Health Centers (FQHC
  Urban Indian Health Centers)
• 3 _at_ each for a total of 312 providers
• MDs, DOs, mid-level providers
• Increased sample to primary care physicians (n50
  each GFP, IM, OB/GYN)
• Oncologists

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NAMCS induction form- new items for 2006

• Number of mid-level providers
• Ask if practice has ability to perform each of 13
  different tests and images
• CT Scan, chemotherapy, MRI, sigmoidoscopy
• If physician sees patients during the evening or
  on the weekend

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NAMCS induction form- new items for 2006 (cont)

• Expanded the questions that ask about EMR
  functionality
• Computerized orders for prescriptions?
• If yes, are there warnings of drug interactions
  or contraindications provided?
• If yes, are prescriptions sent electronically to
  pharmacy?
• Imaging results?
• If yes, are electronic images returned?

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NAMCS induction form- new items for 2006 (cont)

• Pay-4-performance
• Factors that are taken into account for patient
  care compensation
• Productivity, patient satisfaction, quality of
  care, and practice profiling
• Performance measures on practice available to
  public
• of patient care revenue is based on bonuses,
  returned withholds, or other performance-based
  payments
• of patient care revenue from different payment
  sources
• Usual, customary and reasonable fee-for-service
  discounted fee-for-service capitation and case
  rates

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NAMCS induction form- new items for 2007

• Appointments
• same day appointments
• Does practice set time aside for same day
  appointments
• How long does it take to get an appointment
• Series of questions on HPV vaccine
• Recommend, sex and age groups recommended, and if
  not, why they do not recommend

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NAMCS induction form- new items for 2008

• How many hours do you spend in the office
  providing direct patient care?
• Which HPV vaccine does practice recommend using?

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User Considerations
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Encounter vs. person data

• NAMCS / NHAMCS are record-based surveys
• Estimates are in terms of visits and not persons
• Not population-based surveys (NHIS)
• Cannot calculate incidence or prevalence rates
  from NAMCS / NHAMCS estimates

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Sample weight

• Sample data MUST be weighted to produce national
  estimates
• Estimation process
• Adjusts for survey and item nonresponse
• Makes several ratio adjustments within and across
  physician specialties and hospitals

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Sampling error

• NAMCS and NHAMCS are not simple random samples
• Clustering effects
• Providers within PSUs
• Visits within physician practice or hospital
• Must use generalized variance curve or special
  software (e.g., SUDAAN) to calculate SEs for all
  estimates, percents, and rates

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Reliability criteria

• Estimate based on at least 30 raw cases are
  reliable
• Estimate has a relative standard error (RSE) less
  than 30 percent are reliable
• Both conditions must be met

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Ways to improve reliability of estimates

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

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Nonsampling error

• Frame coverage
• Reporting and processing errors
• Biases due to survey and item nonresponse
• Incomplete responses

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Minimizing nonsampling error

• Improve sample frame for better coverage
• Encourage uniform reporting and eliminate
  ambiguities
• Pretest survey items and procedures
• Perform quality control procedures consistency
  and edit checks
• Train Census field representatives

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NAMCS Response rate
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NHAMCS Response rates
ED
OPD
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Attempts to improveresponse rate

• Publicity
• Eliminating questions that have a high item
  non-response
• Methodological studies
• PR material

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Methodological studies

• NAMCS Motivational insert (2000)
• NAMCS and OPD PRF length (2001)
• Incentives test (2002)

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HIPAA

• No directly identifiable information collected
• PHS Act 308(d) / Title 15
• Data Use Agreement w/ Limited Dataset
• IRB approval w/ waiver of patient authorization
• Accounting Document

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HIPAA

• 1-800 telephone number
• Respondent website
• Training
• Written instructions
• CD-ROM
• Self-study
• Follow-up

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Recent future releases

• 2006 NAMCS NHAMCS
• Combined 2006/2007 CHC NHSR
• 2003-06 ED pediatric series report

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Outside research

• Journal articles
• List on Ambulatory Care web site
• Text books
• Department level publications
• Health US

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Microdata files

• Downloadable files
• NAMCS, 1973-2006
• NHAMCS, 1992-2006
• CD-ROMs
• NAMCS, 1990-2005
• NHAMCS, 1992-2005
• Tapes/cartridges (NTIS)
• NAMCS, 1973-1997
• NHAMCS, 1992-1997

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Enhanced public-use files

• New survey items and facility level data
• SAS input statements, variable labels, value
  labels, and format assignments for 1993-2006
• SPSS syntax files
• STATA .do and .dct files for 2002-2006

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Enhanced public-use files

• Sample design variables
• Masked variables for multi-stage sampling are
  available
• 1993-2006 NAMCS and NHAMCS
• Starting in 2002, NAMCS NHAMCS masked variables
  have been available for use in software using
  1-stage sampling. Prior years with formula
• Starting in 2003, we only released masked
  variables for use in software using 1-stage

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Design VariablesSurvey Years
2002
2001
1-Stage design variables 3- or 4-Stage design
variables
3- or 4-Stage design variables
2003
1-Stage design variables only
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Average comparison ratios by alternative standard
error method and type of setting
Source Inquiry 40 401-415 (Winter 2003/2004)
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Scatter plot of masked and unmasked 4-stage WOR
SUDAAN SE for all settings
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Where to get more information

• Call Ambulatory Hospital Care Statistics Branch
  at [phone]
• Public Use Documentation
• or

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http//www.cdc.gov/nchs/about/major/ahcd/ahcd1.htm
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NCHS Research Data Center
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Why the Research Data Center?

• Have access to information not available on
  public use files
• Patient zip code linked income, education, or
  urbanicity status
• Provider physician gender and age, board
  certification, teaching hospital, medical school
  affiliation, ED size
• Supplement data CCSS
• Geographic state and county FIPS codes

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Data Center - cont.

• Can merge with contextual variables (e.g., ARF,
  NHIS, Census, NHDS)
• Health status level
• HMO penetration
• Physician and specialist supply
• Medicaid reimbursement
• Air quality
• Percent in poverty

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Data Center rules

• Submit a proposal
• Cannot use data to identify patients or providers
  or geographic location of providers
• Cannot remove data files
• Fee onsite / remote / file construction

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Examples of facility-level data
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Emergency Pediatric Services and Equipment
Supplement (EPSES)

• Funded by the Health Resources and Services
  Administration
• Added as a supplement to the 2002-03 and 2006
  NHAMCS
• Services related to treating children
• Availability of pediatric supplies

94
Distribution of Hospital Inpatient Pediatric
Structure
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EMR Mail Survey

• Supplement data collected on NAMCS-1
• Collected 2008 2009
• 4-page self administered to 2,000 additional
  physicians
• Questions
• Eligibility
• EMR questions
• Facility level questions known to affect EMR
  adoption
• Practice type size, managed care

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EMR Use in Ambulatory Care
Emergency department
Outpatient department
Physician office
NOTE Office-based physician and hospital
emergency department trends are significant
(plt.05).
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Cervical Cancer Screening Supplement

• Conducted in 2006-2010
• Purpose is to evaluate-
• adherence to HPV DNA testing guidelines
• impact of HPV vaccine on cervical cancer
  screening practices
• Gardasil (approved 6/06 for females 9-26 years
  old)
• Cervarix (approval pending)

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Pandemic and Emergency Response Preparedness
Supplement

• Conducted in 2008
• Supports DHHS goal for emerging health threats
• Assesses progress towards hospital preparedness
  for terrorist attacks, mass casualty incidents,
  pandemics, and natural disasters

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I need more information !

• E-mail pmeyer1_at_cdc.gov
• Website www.cdc.gov/nchs/rd/rdc.htm
• Call [phone]

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Thank You

• Linda McCaig NHAMCS data
• lmccaig_at_cdc.gov
• David Woodwell NAMCS data
• dwoodwell_at_cdc.gov