Analyzing Data from the NAMCS and NHAMCS

1. Analyzing Data from theNAMCS and NHAMCS Linda McCaig and David Woodwell 2006 Data Users Conference July 11, 2006

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

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. Original NAMCS survey goals • National statistics • Professional education • Health policy formulation • Quality assurance

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

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

8. How are NAMCS and NHAMCS data used?

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

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

12. Average length of time for duration of office visits and emergency departments waiting times 60 47.4 50 38 .0 40 Minutes 30 18.7 18.6 20 10 0 1994 2004 1997 2004 Waiting time in emergency Office visit duration departments 1/ 1/ Significant increase since 1997 (p<.01)

14. Percent of ED visits for transient ischemic attack in which a CT or MRI was ordered or performed Source: National Hospital Ambulatory Medical Care Survey, 1992-2001 Citation: Edlow JA, Kim S, Pelletier AJ, Camargo CA Jr. National study on emergency department visits for Transient Ischemic Attack, 1992-2001. Acad Emer Med 2006;April 11

15. Percent of pediatric ED visits with analgesic prescription by pain score Drendel AL et al. Arch Intern Med 2006;117(5):1511-16.

16. Percent of ED visits for attempted suicide according to arrival time Overall Attempted suicide a.m. p.m. Doshi A et al. Ann Emerg Med 2006;46(4):369-75.

18. Trends in office-based visit rates by children and adolescents that included antipsychotic treatment Olfson M et al. Arch Gen Psyc 2006;63:679-685

19. Percent of prescriptions for UTI by drug class in physician offices, OPDs, and EDs Kallen AJ et al. Arch Intern Med 2006;116(6):635-639.

20. NAMCS and NHAMCS Methodology

21. 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

22. 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

23. 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

24. 112 geographic PSUs ~ 3,000 physicians ~ 25,000 visits 1 week reporting period NAMCS Sample design

25. 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

26. 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

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

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

29. 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

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

31. Data processing • Data are coded and keyed by Constella Group Inc. • Quality control procedures • Edit checks by NCHS

32. 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

33. Therapeutic classification system through 2004 • Since 1985, FDA’s NDC therapeutic classification has been used • Limitations • Discontinued by FDA • Only one level of sub-classification

34. Therapeutic classification system - Multum Lexicon • Starting in 2005 • Advantages • Two levels of sub-classification • Regular updates

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

36. 2004 NAMCS PRF

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

38. Patient Record form- common items • Race • Source of payment • Temperature and blood pressure • Reason for visit • Diagnosis

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

40. Injury/poisoning/adverse effect items • External cause – narrative text since 1997 • ED • Intentionality • Work-related

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

42. 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 • Episode of care • Other physicians share care

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

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

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

46. On Patient residence Discharged from any hospital within last 7 days Drug given in ED or prescribed at discharge Reason patient was transferred Off Alcohol related visit Episode of care Modifications to 2005-06 ED PRF

47. Modifications to 2005-06 ED PRF • Information on patients admitted to from the ED • Type of unit • Admission time • Hospital discharge date • Principal hospital discharge diagnosis • Discharged dead or alive

48. On Pregnant (LMP) or gestation week Chronic disease checklist Disease management program Height and weight Medications – new or continued Non-medication treatment Off Episode of care Do physicians share care Cause of injury Modifications to 2005-06 NAMCS/OPD PRFs

49. ED PRF- new items for 2007-08 • Respiratory rate • How many times seen in this ED in last 12 months? • Type of MRI and CT scan • Head or other • Procedure checkboxes – more specific

50. NHAMCS induction form- new items for 2005-06 • Electronic medical records • Mass casualty preparedness • Drills, exercises • ED staffing, capacity, and ambulance diversion • Percent of ED board certified physicians • Number of hours ED was on ambulance diversion • Plans to expand ED physical space