Expanding the National Health Expenditure Accounts (NHEA) Technical Documentation


Chapter 2. Types of Variables


We identified common variables across surveys.  Common variables varied from year to year as the content of surveys has changed over time.  Response scales were recoded to reflect consistency across surveys and years where necessary.


Demographics and Socio-economic status (SES)

Self-reported demographics and SES variables reported in the MCBS and NHANES included age, sex, race, education, poverty status and income, employment status, health insurance status, service in the armed services, marital status, and living conditions including type of dwelling, number of rooms in dwelling and number of people living in the dwelling. 


Participant characteristics

Self-rated health and comparative health status, height, weight, smoking status, and items related to hearing and use of a hearing aid were available in each survey.  Self-reported activities of daily living (ADLs) and instrumental activities of daily living (iADLs) were also included in the data files.  Both surveys also included self-report information related to medical care received including if the respondent had a particular location where routine medical care was received, the last time blood pressure and cholesterol were checked, and if the participant received preventative and screening procedures such as a pneumonia vaccination, pap smear, mammogram, and blood test screening for prostate specific antigen. Information on history of hysterectomy was also collected.


The number of stays and nights a participant spent in a hospital and in an institution was collected.  In the MCBS, this information was also derived from the claim data files.


Disease Groups

Self-report of select diseases including occurrences of select cancers, heart attack, stroke, diabetes, high blood pressure, coronary heart disease, ParkinsonÕs disease, hyperplasia of the prostate, osteoporosis, rheumatoid and non-rheumatoid type arthritis, broken hip, cataracts and paralysis were provided in the survey components of both of MCBS and NHANES. 


Diagnosis code variables obtained from the 7 MCBS claim data files included ICD-9-CM diagnosis codes, ICD procedure codes and HCPCS and CPT procedure codes. Diagnosis code variables were used to identify diseases for which care was sought. A description of disease definition and classification is included in Chapter 3 of this document.


Medical expenditures

Expenditure variables were obtained from the MCBS administrative data. Cost variables included total payment and breakdown by Medicare payment and payment made by other insurance sources, coinsurance/copayment amounts, and patient out-of-pocket payments. The Person Summary file summarizes utilization and expenditure data (1) in total by type of service and (2) in total by payer.


To impute for the presence of disease, we matched on variables common to the MCBS and NHANES.  See Appendix 2a for formats of common variables where applicable.