Analyzing data on medications collected in the National Health Care Survey

1. Analyzing data on medications collected in the National Health Care Survey Catharine W. Burt , Ed.D. Chief, Ambulatory Care Statistics Branch June 6, 2004 AcademyHealth Conference Centers for Disease Control and Prevention National Center for Health Statistics

3. Topics • Overview of the NHCS • Background of the ambulatory care surveys • Using public use files for drug analysis • Examples of drug analyses

4. National Health Care Survey Basic Components Hospital & surgicalcare Ambulatory care Long-term care Health Provider Inventory

5. National Health Care Survey(Year began collecting drug data) • National Ambulatory Medical Care Survey (1980) • National Hospital Ambulatory Medical Care Survey (1992) • National Hospital Discharge Survey (in research) • National Survey of Ambulatory Surgery (1994-6) • National Nursing Home Survey (2004) • National Home and Hospice Care Survey

6. Increasing drug mentions at ambulatory care visits

7. NHCS Common Methodology • National probability sample surveys • Complex sample designs • Common definitions, data items, sampling frames • Medical diagnoses coded to ICD-9-CM • Data collected by Census Bureau • High response rates • Data processed by private contractor

11. Antibiotic prescribing rates at physician office visits for children Rate per 1000 population Rate per 1000 visits

12. NAMCS and NHAMCS background • NAMCS • Fielded 1973-1981, 1985, 1989-present • 3-stage sample • PSUs – physicians – visits during 1 week • NHAMCS • Fielded annually since 1992 • 4-stage sample • PSUs – hospitals – ED/OPD clinics – visits during 4 weeks records sample drugs SEs providers percents visits rates

13. Scope of the NAMCS • Physicians must be: • Primarily engaged in office-based, patient care • Nonfederally employed • Not in anesthesiology, radiology, or pathology

14. In-Scope Visits for NAMCS • Basic unit of sampling is the physician-patient visit • Visit must occur in a physician’s office • Visits must be for medical purposes • Out-of-scope contacts include: • Visits for administrative purposes • House calls, phone calls, emails, visits in hospital setting unless physician has private office there

15. In-Scope NAMCS Locations • Freestanding private solo or group practice • Freestanding clinic/urgicenter • Neighborhood medical and mental health centers • Privately operated clinics • Non-Federal government clinic • Health maintenance organization • Federally qualified health center • Faculty practice plan

16. Out-of-Scope NAMCS Locations • Hospital ED’s and OPD’s • Ambulatory surgicenter • Institutional setting (schools, prisons) • Industrial outpatient facility • Federally operated clinic • Laser vision surgery

17. Scope of the NHAMCS • Basic unit of sampling is patient visit • Emergency and outpatient departments of non-federal, general and short-stay hospitals • Not Federal, military, or Veterans Administration facilities • Located in 50 states and D.C.

19. Items Collected • Patient characteristics • Age, sex, race, ethnicity • Visit characteristics • Source of payment, continuity of care, reason for visit, diagnosis, treatment, medications ordered or provided • Provider characteristics • Physician specialty, hospital ownership • Drug characteristics • Therapeutic class, composition, control status, ingredients, Rx or OTC

21. Using NAMCS/NHAMCS public use files for analyzing drug data

22. Ambulatory Care Data Structure

23. File Structure • Flat ASCII files for each setting and year • Use file layout to read the data • Input and format code available for • SAS • STATA • SPSS • Can use SETS (but no sampling variance estimates)

24. Visit File Layout

25. Sample Weight • Each NAMCS, OPD and ED record contains a single weight, which we call Patient Visit Weight • This weight is used for both visits and drug mentions • Weight must be applied or estimates of totals, percents and effects will be incorrect.

26. Drug coding

27. Leading Rx at office visits% of all Rx mentions • Lipitor 1.6% • Albuterol 1.4 • Amoxicillin 1.3 • Synthroid 1.3 • Lasix 1.2 • Celebrex 1.2 • Vioxx 1.1 Source: 2002 NAMCS

28. Top OTC mentions at office visits% of all OTC mentions • Aspirin 16.7% • Tylenol 11.6 • Advil 4.1 • Prenatal vitamins 3.4 • Benadryl 3.2 Source: 2002 NAMCS

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

31. Drug Characteristics Database Search on Generic: Fluoxetine 1999 Drug Code Drug Name Generic Name Mentions 25674 PROZAC FLUOXETINE HYDROCHLORIDE 9,257,694 91079 FLUOXETINE FLUOXETINE HYDROCHLORIDE 49,293

32. Drug Characteristics Database Drug Code\Name: 25674 - PROZAC Generic Code\Name: 80006 – FLUOXETINE HYDROCHLORIDE Date Added: No Date Prescription Status: 1 - Prescription Drug Composition Status: 1 - Single Entity Drug DEA Status: 6 - No Control Therapeutic Class: 0630 Antidepressants 1999 Mentions: 9,257,694 1999 Mention Rate: 98.0

33. Drug Characteristics Database Drug Code\Name: 91079 - FLUOXETINE Generic Code\Name: 80006 – FLUOXETINE HYDROCHLORIDE Date Added: No Date Prescription Status: 1 - Prescription Drug Composition Status: 1 - Single Entity Drug DEA Status: 6 - No Control Therapeutic Class: 0630 Antidepressants 1999 Mentions: 49,293 1999 Mention Rate: 1.0

34. Drug mention rates at physician office visits by patient’s age: 1985-2002

35. Drug mention rates for NSAIDs, antidepressants, and antihistamines at physician office visits, 1995-2002 NSAIDs Number of drug mentions per 100 visits Antidepressants Antihistamines Trends shown are significant (p<0.05). NSAIDs are nonsteroidal anti-inflammatory drugs.

36. Estrogen/progestin mention rates for women at physician office visits by patient age, 1995-2002 45-64 years Number of drug mentions per 100 females. 65 years and over

37. Rate of office visits for erectile dysfunction for men 25+: United States, 1985-2002 Viagra introduced Figures are based on 2-year averages except 1985. SOURCE: NAMCS

38. Example of NAMCS analysis for Viagra • Prescribed at .4% of office visits by males; 15% of erectile dysfunction (ED) visits • 12% scripts written for men aged 25-44 and 9% for 75+ • Rate of scripts increases for patients who have seen their physician between 1 and 5 times in past year. Rarely prescribed at an initial visit. • Only 19% of scripts written are at ED visits • Leading diagnoses when ED not listed– • Essential hypertension 19% • Hyperplasia of the prostate 11% • Diabetes 8%

39. Analyzing trends • Be careful about trending diagnosis prior to 1980 because of ICDA (based on ICD-8) • Even after 1980- be careful about changes in ICD-9-CM • Number of medications varies over years 1980-81 – 8 medications 1985, 1989-94 – 5 medications 1995-2002 – 6 medications 2003-2006 – 8 medications • Number of therapeutic class codes vary 1980-2001 – 1 class 2002-2006 – up to 3 classes

40. Information available on the Internet • NCHS website is www.cdc.gov/nchs • National Health Care Survey website • Ambulatory Health Care Data (AHCD) • National Hospital Discharge and Ambulatory Surgery Data (NHDAS-data) • National Nursing Home Survey (NNHS) • National Home and Hospice Care Survey (NHHCS) • Join our LISTSERVs