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Responses to Recent Health Policy Data Requests

Trends in Health Care Coverage and Insurance
from 1959-2007

 

These three tables and related information also appear in a report, "Health Insurance Coverage Trends, 1959-2007: Estimates from the National Health Interview Survey" [PDF - 330 KB] which was released in July 2009. Some minor edits have been made to the material below on methods and definitions, and to table footnotes so that they are consistent with the July 2009 report. All estimates in the tables are unchanged since their initial release in May 2009.

 

The three tables present long-term trends in the number and percentage of persons under 65 years of age with different types of health insurance coverage and with no coverage.  Estimates were derived from 32 years of the National Health Interview Survey (NHIS) over the period 1959 to 2007.  The types of estimates available differ over these years, reflecting changes in the availability of different types of coverage and changes in the NHIS questions. Interpretation of the trends in coverage estimates requires consideration of how health insurance coverage and the collection of information on coverage have changed over time. Trends in estimates of coverage may reflect changes in the NHIS as well as actual changes in the percentage and number of people with different types of coverage. Technical information on the data source, tables, and definitions of NHIS coverage categories are provided below.

 

Data Source and Methods

The National Health Interview Survey (NHIS) is the source of data shown in Tables A, 1 and 2. NHIS is a continuous multistage probability sample survey of the civilian noninstitutionalized population of the United States. It is a multipurpose health survey conducted by the Centers for Disease Control and Prevention’s (CDC) National Center for Health Statistics (NCHS). NHIS interviewers are from the U.S. Census Bureau.  Information on basic health topics is collected for all household members, by proxy from one family member if necessary (all members of the household 17 years of age and over who are home at the time of the interview are invited to participate and respond for themselves). More information is on the National Health Interview Survey homepage.

The sample size of the NHIS varied over the years 1959-2007.  The sample sizes for the insurance questions in 1959 and 1962-63 were approximately 62,000 and 138,000 persons respectively.  The number of persons under age 65 who received the health insurance questions was 90,000 or higher in most years from 1968-1997.  The largest sample size was 120,670 in 1968.  In a few years (1970, 1983, 1986, 1993, and 1996), only a subset of the sample or a part-year sample received the health insurance questions, resulting in sample sizes ranging from 44,373 to 56,268. More recently, during the period 1997-2007, the sample size under age 65 declined from 91,275 to 67,065.    

Estimates were calculated using the NHIS survey weights, which are calibrated to census totals of the U.S. civilian noninstitutionalized population by sex, age, and race or ethnicity.  The 1959 NHIS weights were derived from the 1950 census-based population estimates. From fiscal year 1963 through calendar year 1974, the weights were derived from the 1960 census-based population estimates.  The 1976 - 1980 weights were derived from 1970 census-based population estimates. The 1982 to 1994 weights were derived from the 1980 census-based population estimates. The 1995 to 2002 weights were derived from the 1990 census-based population estimates. Starting with 2003, weights were derived from 2000 census-based population estimates.

Point estimates and their standard errors were calculated using SUDAAN software to account for the complex sample design of NHIS. Estimates shown in the tables meet the NCHS standard of having a relative standard error less than or equal to 30%. 

Response rates for the period ranged between 86%-98%, depending on placement of the insurance questions.  In the tables, unknown values (responses coded as “refused”, “not ascertained”, or “don’t know”) were not counted in the denominators when calculating estimates.  The item nonresponse rate for the health insurance items used in the tables ranged between 0.5 and 3.5% during 1963-2007.  In 1959, the item non-response rate was almost 2% for the hospital insurance question and almost 5% for the surgical insurance question.

 

Notes concerning Tables A, 1 and 2

  • There may be a lag between the introduction of new health insurance programs, payers and regulations and their integration into the NHIS.
  • During 1959 to 1968, insurance coverage data were collected in the NHIS in three years (1959, fiscal year 1963, and 1968); during 1968 to 1989 such data were generally collected every two years; and from 1989 on they were collected every year.  
  • Questions about private health insurance coverage were asked in all years included in the tables, and employer-sponsored coverage questions were asked starting in 1970.  Direct questions about Medicaid and Medicare coverage (for persons under age 65) were asked starting in 1978, and about military coverage starting in 1982. Prior to 1978, information about public coverage could be inferred in some years through responses to questions that did not ask about public coverage directly. 
  • During 1976 to 2007, persons in the NHIS were categorized into one or more of the following health insurance coverage groups: any private coverage, employer-sponsored private coverage, other private coverage, Medicaid, Medicare, other public coverage, and uninsured.  During 1968 to 1974, persons were classified into some but not all of these groups, based on the questions available in each year. For more information on the definitions of these groups see the section on NHIS coverage categories in Definitions. 
  • In 1976-1996 only, questions on receipt of AFDC and SSI were used to assign Medicaid coverage to recipients of those programs.   
  • From 1959 to 1980, NHIS insurance questions asked about hospital insurance and insurance plans that paid for doctors’ or surgeons’ bills. In 1982, the separate associations for Blue Cross (covering hospitalizations) and Blue Shield (covering physician care) merged, making the separation between hospital and physician insurance less distinct.
  • During 1970 to 2007, estimates of the percentage of persons in each category are shown for persons under age 65 because almost all persons ages 65 and over had coverage through the Medicare program.   
  • During 1959 to 1968, persons were categorized according to whether or not they had any hospital insurance and surgical insurance, and estimates are shown for persons of all ages, under 65 years of age, and 65 years and over. 
  • The recall period for the insurance questions is the day of the interview except in 1990-1996 when questions refer to the month prior to the interview, resulting in a recall period of 1-2 months, depending on the time of the month when the interview occurred.

 

Definitions of NHIS coverage categories

 

1968-2007

 

Private coverage includes comprehensive health care coverage obtained through an employer, purchased directly, or obtained through any other means. It excludes plans that pay for only one type of service such as accidents or dental care.  Private coverage is at the time of interview, except in 1990-1996, when it is for the month prior to the interview.

  • Employer-sponsored private coverage is private insurance originally obtained through the workplace that is, either through a present or former employer or union. In 1997-2007, this category explicitly includes coverage obtained through self-employment and professional associations. Persons who had more than one private insurance plan were classified as having employer-sponsored private coverage if any of their plans were employer-sponsored.
  • Other private coverage refers to private insurance that was not employer-sponsored. This includes directly purchased plans as well as plans obtained through school or other means. Persons who had more than one private insurance plan were classified as having other private coverage only if no plans were employer-sponsored.

Public coverage

  • The Medicaid coverage category includes persons who reported having Medicaid coverage (1990-2007) or having a Medicaid card (1978-89) or not carrying (private) health insurance because care was received through Medicaid or welfare (1972-1980).  In addition, the Medicaid category includes those who reported coverage by “any other public assistance program that pays for health care” in 1982-1989 and 1992-1996; a state-sponsored health plan in 1997-2007; and the Children’s Health Insurance Program in 1999-2007. Finally, in 1976-1996, persons who did not report Medicaid coverage, but did report receiving Aid to Families with Dependent Children or Supplemental Security Income were assigned Medicaid coverage because persons in those programs were automatically enrolled in Medicaid.  Medicaid coverage is at the time of interview, except in 1990-1996, when it is for the month prior to the interview.
  • The Medicare coverage category refers to coverage at the time of interview, except in 1990-1996, when it is for the month prior to the interview.  In 1976, persons were assigned Medicare coverage if they reported not being covered by any (private) health insurance plan because care was received through Medicare.  In 1968-74 no information on Medicare was collected for persons under age 65. 
  • The other public coverage category refers to coverage at the time of interview, except in 1990-1996, when it is for the month prior to the interview.  It includes military coverage (1982-2007),   coverage through “other government programs” (1997-2007), and not carrying (private) health insurance because of military coverage (1972-1980).  Military coverage includes TRICARE (CHAMPUS), CHAMP-VA, and VA coverage.

The uninsured category includes persons who have no private health insurance, Medicaid, military coverage, Medicare (1976-2007), or coverage through “any other public assistance program that pays for health care” (1982-1989 and 1992-1996), the Children’s Health Insurance Program (1999-2007), or a state-sponsored health plan or other government program (1997-2007).  In addition, in 1976-1996, the uninsured include persons who did not report any type of public or private health care coverage and also did not report receiving Aid to Families with Dependent Children (AFDC) or Supplemental Security Income (SSI).  A person was also defined as uninsured if he or she had only Indian Health Service coverage or only had a private plan that paid for one type of service such as accidents or dental care.

 

1959, 1962-1963, 1968, and 1970

 

The term, health insurance, refers to private insurance in the 1959, 1962-63, 1968, and 1970 NHIS, and is any plan specifically designed to pay all or part of the medical or hospital expenses of the insured individual.  The insurance can be either a group or an individual policy with the premiums paid by the individual, an employer, a third party, or a combination of these. Benefits received under the plan can be in the form of payment to the individual or to the hospital or doctor.  However, the plan must be a formal one with defined membership and benefits rather than an informal one.  For example, an employer simply paying the hospital bill for an employee would not constitute a health insurance plan.   For the NHIS in these years, (private) health insurance excludes the following  kinds of plans: (1) plans limited to the “dread diseases”, such as cancer and polio; (2) “free care” such as public assistance or public welfare or Medicaid (as of 1968), care given free of charge to veterans, care given to dependents of military personnel, care given under the Uniformed Services Dependents Medical Care Program, Crippled Children or similar programs, and care of persons admitted for research purposes; (3) insurance which pays bills only for accidents, such as liability insurance held by a car or property owner, insurance that covers children for accidents at school or camp, and insurance that that covers workers only for accidents, injuries, or diseases incurred on the job: and (4) insurance which pays only for loss of income.

Hospital insurance pays all or part of the hospital bill for the hospitalized person.  By hospital bill is meant only the bill submitted by the hospital itself, not the doctor’s or surgeon’s bill or the bill for the special nurses.  Such a bill always includes the cost of room and meals and may also include the costs of other services such as operating room, laboratory tests, and X-rays.

Surgical insurance pays in whole or part the bill of the doctor or surgeon for an operation whether performed in a hospital or in the doctor’s office.  Insurance which pays the costs of visits to a doctor’s office for postoperative care is included as surgical insurance.

 

 

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