Medication Data from Nationally Representative Provider- and Population-Based Surveys Lisa L. Dwyer, MPH Saeid Raofi, MS Pharmacy Karen A. Lees, MPH Ryne Paulose, PhD National Center for Health Statistics 2006 Data Users Conference (Session #50) Washington, D.C. July 12, 2006
Background • NCHS is the Nation’s principal health statistics agency • compile statistical information to guide actions and policies to improve the health of our people • provide public use files of survey data to the public • Congress • researchers • health planners
Background • Our health statistics allow us to: • document the health status of the population • monitor trends in health status and health care delivery • support biomedical and health services research • provide information to guide and evaluate health policy decisions and programs
Background • NCHS surveys that have collected medication data: • National Health Care Survey (NHCS) • National Ambulatory Medical Care Survey (NAMCS) • National Hospital Ambulatory Medical Care Survey (NHAMCS) • National Nursing Home Survey (NNHS) • National Hospital Discharge Survey (NHDS) • National Health and Nutrition Examination Survey (NHANES)
Background • National Health Care Survey • family of mostly provider-based surveys • collects information about health care facilities, their services, and their patients • National Health and Nutrition Examination Survey • population-based survey • consists of a household interview, medical/dental examinations, and lab tests
Objectives • To describe how the National Center for Health Statistics (NCHS) collects medication data across its surveys • To describe how our data can be used to generate national estimates • To discuss the future direction of NCHS surveys
Prescription Medications • Drugs and their associated costs are at the forefront of national health care debates. • According to figures reported by CMS, prescription drug expenditures increased at a much faster rate than the total health care expenditure for most of 1995-2004. • Access to and affordability of drugs for the elderly were major drivers behind the Medicare Part D Drug Benefit implementation.
Health Care Expenditures Source: Centers for Medicare & Medicaid Services; www.cms.hhs.gov/NationalHealthExpendData/
Drug Utilization • This increase in cost is driven, in part, by an increase in utilization. • The national ambulatory health care surveys show that the number of drugs mentioned per visit increased between the 10-year period, 1993/1994 and 2003/2004. • Previous study reports that medication use is highest among the institutionalized elderly. This population continues to increase.
Increase in Drug Mention Rates Source: 1993-1994, 2003-2004 NAMCS and NHAMCS
Collection and Processing of Drug Information in National Ambulatory Medical Care and National Hospital Ambulatory Medical Care Surveys
Drug Data Collection in National Health Care Surveys • I will focus on the National Ambulatory Health Care surveys, NAMCS and NHAMCS, which have collected drug data the longest. • The system developed for the processing and coding of the collected drug data for NAMCS and NHAMCS will be used for processing of the data in other surveys as well. • I will also give a detailed description of this processing and coding system.
NAMCS and NHAMCS Background • NAMCS • Fielded 1973-1981, 1985, 1989-present • Began collecting drug data in 1980 • NHAMCS • Fielded annually since 1992 • Began collecting drug data in 1992
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
NCHS Common Methodology • National probability sample surveys • Complex sample designs • Common definitions, data items, sampling frames • Medical diagnoses coded to ICD-9-CM • High response rates • Data processed by private contractor
NAMCS and NHAMCS Sample Design • NAMCS • 3-stage sample PSUs – physicians – visits during 1 week • NHAMCS • 4-stage sample PSUs – hospitals – ED/OPD clinics – visits during 4 weeks
Generating National Estimates from Samples • Statistics from the NAMCS and NHAMCS are derived by a multistage estimation procedures that produce essentially unbiased national estimates. • The basic components of estimation are: • Inflation by reciprocals of the sampling selection probabilities • Adjustment for nonresponse • Weight smoothing • A calibration ratio adjustment
Sample Weight • The estimation procedure produces a single weight, called Patient Visit weight, for each NAMCS, OPD, and ED record. • This weight is used for both visits and drug mentions. • Weight must be applied or estimates of totals, percents and effects will be incorrect.
Definition of Drug Mentions A drug mention is the provider’s entry of drugs (prescription or over the counter), immunizations, allergy shots, anesthetics, chemotherapy, and dietary supplements that were ordered, supplied administered or continued during the visit.
Drug Data Processing • Since 2003, the provider can list up to eight drug mentions on the survey form. From 1995 to 2002 the provider could enter up to six drug mentions and before then up to five mentions. • Each drug mention will be associated with a drug code at data entry stage. • Drugs not in the database will be assigned a new unique code.
Adding Drug Characteristics • Upon completion of visit files, the following drug characteristics are added to visit files for each drug mention • Generic name • Therapeutic class • Ingredients • Composition • Control status • Rx or OTC
Utility of Drug Characteristics • Drug characteristics can be used to create summary reports based on therapeutic class, active ingredients, etc. • They can be used in combination with patient and visit characteristics to study pharmacotherapy in specific disease areas. • They can be used in combination with physician characteristics in studies looking at prescribing behavior.
Example: Mentions of Antihypertensive Drugs for Ages 55-64 from 1999-2002
Therapeutic Classification System Through 2004 • Since 1985, the FDA’s NDC therapeutic classification has been used • Limitations of this system: • Only has one level of sub-classification • FDA has discontinued this product
Adoption of Multum Lexicon as the Therapeutic Classification System • Starting with 2005 data, Multum therapeutic classification system will be used for classifying NAMCS and NHAMCS drug data. • This system has two level of sub-classification. • It is regularly updated.
Example: Classification of Paroxetine by the two classification systems • NDC system • 0600 central nervous system • 0630 antidepressants • Multum Lexicon system • 242 psychotherapeutic agents • 249 antidepressants • 208 SSRI antidepressants
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)
Ambulatory Health Care Data http://www.cdc.gov/nchs/about/major/ahcd/ahcd1.htm
Example of Drug Lookup Function • By brand name PAXIL • BY GENERIC NAME PAROXETINE http://www2.cdc.gov/drugs/
For more information on the NAMCS and NHAMCS, please visit http://www.cdc.gov/nchs/about/major/ahcd/ahcd1.htm
2004 National Nursing Home Survey • Nationally representative sample survey of U.S. nursing homes • services/programs • staff • residents • Conducted periodically since 1973-74 • 1977, 1985, 1995, 1997, 1999, 2004
2004 National Nursing Home Survey • Taken out of the field after the 1999 survey for a major redesign. • Put back into the field in 2004 • computerized data collection • many new content items, including collection of medication data • supplemental survey on nursing assistants, NNAS
2004 National Nursing Home Survey • Two-stage probability survey design • nursing home facility • residents (up to 12 current residents)
2004 National Nursing Home Survey • Sampling frame • Centers for Medicare and Medicaid Services Provider of Services file of U.S. nursing homes • state licensing lists compiled by private organization • total of 16,628 nursing homes in frame
2004 National Nursing Home Survey • Eligibility criteria • licensed by State as a nursing facility • certified and non-certified facilities • three or more beds
2004 National Nursing Home Survey • Survey items • medications taken 24 hrs before facility interview • standing or routine medications, or PRNs • up to 25 medications • medications taken regularly but not 24 hrs before facility interview • up to 25 medications • reason medications were prescribed
2004 National Nursing Home Survey • Medication data • found in medication administration records • did not collect dosage, frequency, route • collected during in-person interview at facility • entered into CAPI system by interviewer • processed like NAMCS/NHAMCS data