Analyzing data on medications collected in the National Health Care Survey

1. U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Center for Health Statistics Analyzing data on medications collected in the National Health Care Survey Catharine W. Burt , Ed.D. Chief, Ambulatory Care Statistics Branch July 14, 2004 Data Users Conference

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