Overview of the NAMCS and NHAMCS

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)

7. 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

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

11. The IOM report

12. 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 2006;355:1300-1303

13. 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 1 719,000 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. 2008;Jan-Feb:w84-w93.

16. Ambulatory care visit rates by setting *p<0.05.

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 p<0.05.

19. Indicator performance by use of electronic health records in physician offices 1 Note: All comparisons are significant (p< 0.01).UA is urinalysis. SOURCE: Linder JA et al. Archives of Internal Medicine. 2008;167:1400-1405.

20. Percentage of OPD visits by adults 18 years and over with selected chronic conditions NOTE:COPD is chronic obstructive pulmonary disease. 1 (p<0.05).

21. NAMCS and NHAMCS Methodology

22. 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

23. 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

24. 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

25. 112 geographic PSUs ~ 3,700 physicians ~ 29,000 visits 1 week reporting period NAMCS Sample design

26. 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

27. 112 geographic PSUs ~ 500 hospitals ~ 400 EDs and ~ 250 OPDs ~ 37,000 ED and ~ 35,000 OPD visits 4-week reporting period NHAMCS Sample design

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

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

30. 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 bachelor’s degree or higher, urban/rural

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

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

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

34. Therapeutic classification system • 1985-2005, FDA’s NDC therapeutic classification was used • Limitations • Discontinued by FDA • Only one level of sub-classification

35. Therapeutic classification system - Multum Lexicon • Starting with 2006 data • Advantages • Two levels of sub-classification • Regular updates

36. Example: Classification of paroxetine • NDC • 0600 central nervous system • 0630 antidepressants • Multum Lexicon • 242 psychotherapeutic agents • 249 antidepressants • 208 SSRI antidepressants

37. 2006 NAMCS PRF

38. Patient Record form (PRF) • Common items • Unique items • 2007-08 modifications • 2009-10 proposed changes

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

40. Patient Record form- common items • Race • Source of payment • Temperature and blood pressure • Reason for visit • Diagnosis • Injury, poisoning, adverse effect

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

42. 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

43. 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

44. ED Patient Record form- unique items • Hospital admission • type of unit • time of admission • date of discharge • principal hospital discharge diagnosis • discharge status

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

46. NAMCS and OPD PRFcontinuity 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

47. 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 Modifications to 2007-08 ED PRF

48. On None Off Patient pregnant LMP or gestation week Modifications to 2007-08 NAMCS/OPD PRFs

49. 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

50. 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