1. 1 Linda McCaig and David Woodwell Ambulatory Care Statistics Branch Division of Health Care Statistics Overview of the NAMCS and NHAMCS

2. 2 Overview Background Data uses Survey methodology Current and proposed survey items User considerations Methodological studies Data dissemination NCHS Research Data Center

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4. 4 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

5. 5 Original NAMCS survey goals National statistics Professional education Health policy formulation Medical practice management Quality assurance

6. 6 NAMCS history Survey began in 1973 Annual data collection through 1981 (NORC) Conducted in 1985 (NORC) Annual began again in 1989 (Census)

7. 7 NHAMCS history Survey began in 1992 Annual data collection (Census)

8. 8 How are NAMCS and NHAMCS data used?

9. 9 Data uses Understand health care practice Examine the quality of care Track certain conditions Find health disparities Measure Healthy People 2010 objectives Serve as benchmark for states

10. 10 Data users Over 100 journal publications in last 2 years Medical associations Government agencies Health services researchers University and medical schools Broadcast and print media

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13. 13 Total Ambulatory Care Visits SOURCE: CDC/NCHS, NAMCS and NHAMCS, 2001.

14. 14 Annual rate of injury-related ED visits for seniors by patient residence Age in years InstitutionCommunity Number of visits per 100 persons 65-79 418 80+ 3714

15. 15 Percent of physician office visits by type of cardiac rhythm modifying agent Fang et al. Arch Intern Med 2004;164(1):55-60.

16. 16 Percent of selected ED visit characteristics among released patients who had a blood culture Visit characteristic Antibiotics prescribed Antibiotics not prescribed Total Fever19%17%36% No fever28%36%64% Total47%53%100%

17. 17 Potentially inappropriate drug prescribing at elderly physician office visits Goulding. Arch Intern Med 2004;164(3):305-312.

18. 18 Number and rate of physician office visits for diabetes Number of visits in millions Rate per 100 persons Grant et al. Arch Intern Med 2004;164(10):1134-1139.

19. 19 Annual rate of injury-related ED visits for children by diagnosis Head wound Other wound Intracranial Poisoning

20. 20 Variations in drug mention rates for selected therapeutic classes by source of payment

21. 21 Variations in drug mention rates for selected therapeutic classes by MSA status

22. 22 HP2010 Objectives on antibiotic prescribing Ear infections (Antibiotics per 1000 persons) Common cold (Antibiotics per 1000 persons) Baseline69325 1998/9954518 2000/0159518 Target56113

23. 23 NAMCS and NHAMCS Methodology

24. 24 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

25. 25 In-Scope NAMCS locations Freestanding clinic/urgicenter Federally qualified health center Neighborhood and mental health centers Non-federal government clinic Family planning clinic HMO Faculty practice plan Private solo or group practice

26. 26 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

27. 27 NAMCS Sample design 112 geographic PSUs 3,000 physicians 25,000 visits – 1 week reporting period

28. 28 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

29. 29 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

30. 30 Gaining cooperation Gaining cooperation Advance letters Endorsement letters Public relations materials Conversion of refusal

31. 31 Data collection procedures Induction visit by Census field representative (FR) FR training of office/hospital staff Take every number Prospective or retrospective method

32. 32 Items collected on Patient Record form (PRF) Patient characteristics – age, race, sex Visit characteristics – reason for visit, diagnosis, medication Provider characteristics – physician specialty, hospital ownership

33. 33 Repeating fields Reason for visit (3) Cause of injury (3) Diagnosis (3) Ambulatory surgical procedures (2) Medications (8)

34. 34 Data processing Data are coded and keyed by Constella Group Inc. (CG) Quality control procedures Edit checks by NCHS

35. 35 Coding systems used A Reason for Visit Classification (NCHS) ICD-9-CM – diagnoses – external causes of injury – procedures Drug coding system (NCHS) National Drug Code Directory

36. 36 NAMCS and NHAMCS 2001-2004 PRFs

37. 37 Patient Record form - common items Patient’s zip code Date of visit Date of birth Sex Ethnicity

38. 38 Patient Record form - common items Race Source of payment Reason for visit Diagnosis

39. 39 Patient Record form – common items Diagnostic/screening services Medications and injections Providers seen Visit disposition

40. 40 Injury/poisoning/adverse effect items External cause – narrative text since 1997 ED – intentionality – work related

41. 41 NAMCS and OPD PRF - unique items Does patient use tobacco Counseling/education/therapy Surgical procedures Time spent with physician (NAMCS only)

42. 42 2001-2004 NAMCS and OPD PRF continuity of care items Patient’s primary care physician/provider Was patient referred for visit Patient seen before Seen how many times in past 12 months Major reason for visit Episode of care Other physicians share care

43. 43 ED Patient Record form - unique items Arrival time Discharge time Time seen by physician Mode of arrival Immediacy

44. 44 ED Patient Record form - unique items Presenting level of pain Alcohol related visit Work related visit Procedure checklist

45. 45 ED Patient Record form - continuity of care items Seen ED within last 72 hours Episode of care – Initial or followup visit

46. 46 Recycled items on 2003-04 ED PRF On – Time seen by physician – Mode of arrival – Presenting level of pain Off – Visit related to an adverse drug event

47. 47 NAMCS and OPD PRF revisions 2005-06 – emphasis on chronic conditions

48. 48 NAMCS and OPD PRF- new items for 2005-06 – Arthritis – Asthma – Cancer – Cerebrovascular disease – CHF – Chronic renal failure – COPD – Depression – Diabetes – Hyperlipidemia – Hypertension – Ischemic heart disease – Obesity – Osteoporosis

49. 49 NAMCS and OPD PRF - new items for 2005-06 Vital signs – Height – Weight – Temperature – Blood pressure Disease management program Medication – new or continued

50. 50 ED PRF - new items for 2005-06 Homeless Discharged from any hospital within last 7 days Medication given in ED or prescribed at discharge Reason patient was transferred

51. 51 ED PRF - new items for 2005-06 Admit to hospital – Critical care/Intervention/Other bed – Hospital admission time – Hospital discharge date – Principal hospital discharge diagnosis – Alive/Dead

52. 52 Examples of Collaboration with Other Government Agencies

53. 53 Emergency Pediatric Services and Equipment Supplement (EPSES) Funded by the Health Resources and Services Administration Added as a supplement to the 2002-03 NHAMCS – Services related to treating children – Availability of pediatric supplies

54. 54 Medical SpecialtyNumber of EDs Percent of EDs Board Certified Emergency Medicine Attending Physician 3,55073 Board Certified Pediatric Emergency Medicine Attending Physician 1,27026 Board Certified Pediatric Attending Physician 3,24967 Attending Physician Specialty (available 24/7 in-house or on-call)

55. 55 Bioterrorism and mass casualty preparedness Funded by the DHHS Assistant Secretary for Planning and Evaluation 2003-4 NAMCS Physician induction interview –Diagnosis of terror-related conditions –Assistance in making a diagnosis –Reporting a suspect case 2003-04 NHAMCS supplement –Hospital response plan, training, and resources

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57. 57 2003-04 NHAMCS Supplements Hospital inpatient occupancy rate ED capacity and staffing –Number of treatment spaces –Percent of vacant nursing positions –Physicians employed by hospital or contractor Ambulance diversion –Percent of days on diversion –Mean number of hours on diversion

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59. 59 Percent distribution of hospital emergency departments by safety-net criteria

60. 60 Percent distribution of emergency department visits by selected characteristics according to size of annual visit volume

61. 61 Percent of physicians accepting new patients by pay source

62. 62 Overview User considerations – Encounter vs. person data – Sampling error – Nonsampling error Methodological studies HIPAA Data dissemination NCHS Research Data Center

63. 63 Encounter vs. person data NAMCS and NHAMCS are record- based surveys Not population-based surveys (NHIS) Estimates are in terms of visits and not persons Cannot calculate incidence or prevalence rates from our estimates

64. 64 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

65. 65 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.

66. 66 Reliability criteria Estimates based on at least 30 raw cases are reliable Estimates with a relative standard error (RSE) less than 30 percent are reliable Both conditions must be met

67. 67 Ways to improve reliability of estimates Combine NAMCS, ED and OPD data to produce ambulatory care visit estimates Combine multiple years of data

68. 68 Nonsampling error Frame coverage Reporting and processing errors Biases due to survey and item nonresponse Incomplete responses

69. 69 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

70. 70 NAMCS Response rate

71. 71 NHAMCS Response rates ED OPD

72. 72 Attempts to improve response rate Publicity Eliminating questions that have a high item non-response Methodological studies

73. 73 Methodological studies Complement study 1997-1999 500 physicians in each year 17% of classified as nonoffice-based saw patients Represented 11% of total Difference not accounted for in weighting

74. 74 Methodological studies NAMCS Motivational insert Conducted last half of 2000 Insert (n=513); no insert (n=499) RR - 68% vs. 64% No difference in RR

75. 75 Methodological studies NAMCS and OPD PRF length Conducted 2001 NAMCS: short (n=941); long (n=969) OPD: short (n=132); long (n=129) NAMCS RR - 68% (short) vs. 62% (long) NAMCS short PRF had a higher RR No effect on RR in OPD

76. 76 Methodological studies Incentives test Conducted last 3 quarters of 2002 3 groups: control (n=418), gift (n=401), and monetary (n=456) RR – 73%, 68%, and 73%, respectively No difference in RR between incentive groups

77. 77 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

78. 78 HIPAA 1-800 telephone number Respondent website www.cdc.gov/namcs www.cdc.gov/nhamcs Training Written instructions CD-ROM Self-study Follow-up

79. 79 Impact of HIPAA on 2003 NAMCS and NHAMCS Induction process in hospitals is longer due to additional levels of approval process Less likely to allow FR abstraction Response rate not affected 2004 may be more difficult…

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81. 81 Outside research Journal articles –List on Ambulatory Care web site Text books Department level publications –Health US

82. 82 Microdata files Downloadable files NAMCS, 1973-2002 NHAMCS, 1992-2002 CD-ROMs NAMCS, 1990-2002 NHAMCS, 1992-2001 (2002 in Aug.) Tapes/cartridges (NTIS) NAMCS, 1973-1997 NHAMCS, 1992-1997

83. 83 Enhanced public-use files New survey items and facility level data SAS input statements, variable labels, value labels, and format assignments –1993 – 2002 for NAMCS –1995 – 2002 for NHAMCS SPSS & STATA input statements, variable labels, value labels, and format assignments in 2002

84. 84 Enhanced public-use files Sample design variables –Masked variables for multi-stage sampling are available: 1993-2002 NAMCS 1995-2002 NHAMCS –In 2002, NAMCS & NHAMCS will have masked variables for use in software using 1- stage sampling. Prior years with formula –In 2003, we will only release masked variables for use in software using 1-stage

85. 85 2001* 3- & 4-Stage design variables 2003 2002 1-Stage design variables only 1-Stage design variables 3- & 4-Stage design variables Design Variables—Survey Years *Plan to re-release years with 1-stage design variables.

86. 86 Ratio of masked to unmasked SUDAAN standard errors using four-stage WOR Source: Inquiry 40: 401-415 (Winter 2003/2004)

87. 87 Average comparison ratios by alternative standard error method and type of setting Type of settingMasked 4- stage WOR SUDAAN Masked 1- stage WR SUDAAN Masked SURVEY- MEANS GVC All settings1.03 1.020.84 Physician’s offices 1.02 1.010.93 Hospital OPD0.991.031.020.94 Hospital ED1.031.06 0.91 Source: Inquiry 40: 401-415 (Winter 2003/2004)

88. 88 Scatter plot of masked and unmasked 4-stage WOR SUDAAN SE for all settings

89. 89 Future releases 2003 NAMCS & NHAMCS in Spring 2005 All settings Series report in Fall 2004 with NAMCS data for primary care and surgical and medical specialties

90. 90 Where to get more information Ambulatory Care information booth Ambulatory Care website – Ambulatory Care listserve Call Ambulatory Care Statistics Branch at (301) 458-4600

91. 91 http://www.cdc.gov/nchs/about/major/ahcd/ahcd1.htm

92. 92 NCHS Research Data Center

93. 93 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, provider weight – Geographic: state and county FIPS codes

94. 94 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

95. 95 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

96. 96 I need more information ! Visit the Research Data Center booth E-mail: rdca@cdc.gov Website: www.cdc.gov/nchs/r&d/rdc.htm Call (301) 458-4277

97. 97 Thank You Linda McCaig – NHAMCS data lmccaig@cdc.gov David Woodwell – NAMCS data dwoodwell@cdc.gov

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