Numerous studies have shown that people without health insurance use fewer health care services1-4 and report greater unmet health care needs5 than people with health insurance. However, far fewer studies have examined the effects on health of being uninsured. In the general population, persons without health insurance have a higher mortality rate than persons with private insurance.6,7 There is a similar difference between uninsured and insured women with breast cancer.8 Less is known about the effects of being uninsured on overall health and physical functioning. In two studies, persons who lost insurance coverage reported poorer general health and worse blood-pressure control than those who maintained insurance coverage.9-11 However, access to care for the uninsured varies greatly among communities,12 so the independent association between the lack of health insurance and the risk of a decline in health is not well defined.
Approximately 16 percent of adults in late middle age in the United States are uninsured.13 The proportion of people 55 to 64 years old who were uninsured increased from 12.9 percent in 1998 to 16.1 percent in 1999.13,14 This group may be particularly vulnerable to the ill effects of being uninsured. Using data from the Health and Retirement Study, we examined the relation between the lack of health insurance and changes in health over four years for adults who were 51 to 61 years old in 1992.
METHODS
Study Population
Our study was approved by the institutional review board of the MetroHealth Medical Center. The Health and Retirement Study is a nationally representative, longitudinal study sponsored by the National Institute on Aging and conducted by the Institute for Social Research at the University of Michigan. Analyses were conducted with the use of publicly available data files from the Health and Retirement Survey.15 That study targeted community-dwelling adults in the contiguous United States who were 51 to 61 years old in 1992. Blacks, Hispanics, and Florida residents were oversampled. The spouses or partners of participants who were not eligible for the study themselves because of their age were interviewed, but we excluded them from our analysis because they are not representative of the U.S. population. In the Health and Retirement Study, in-home interviews were conducted in 7702 households (an 82 percent response rate), yielding 9824 participants between 51 and 61 years old for the initial interview. Follow-up interviews were conducted every two years. Vital status was determined through the National Death Index and household contacts.
We restricted our study to participants who reported having private health insurance or no insurance in 1992. We excluded those who were covered by Medicare or Medicaid at base line, because these persons are likely to have had qualifying medical conditions (e.g., renal failure) or disabilities that were not fully measured in the Health and Retirement Study. Participants who were covered exclusively by the Department of Veterans Affairs or the Civilian Health and Medical Program of the Uniformed Services at base line were also excluded, but those who had private insurance in addition to such coverage were included and classified as insured.
Insurance Status
Insurance status was determined for 1992 and 1994. Participants were classified as uninsured if they did not have public or private insurance at the time of their interview or if they had only catastrophic coverage. For 1992, participants were classified as insured if they had private insurance. For 1994, participants were classified as insured if they had either private or public insurance. Thus, the 244 participants who switched to coverage by Medicare or Medicaid in 1994 were included in all analyses and were classified as insured in 1994 regardless of whether or not they were insured in 1992. Participants were then classified as continuously insured (insured in both 1992 and 1994), continuously uninsured (insured neither in 1992 nor in 1994), or intermittently uninsured (uninsured either in 1992 or in 1994).
Covariates
All multivariate models were adjusted for age, sex, race or ethnic background, marital status, educational level, household income, past or current smoking, alcohol consumption, and number of positive responses on the CAGE questionnaire.16 This questionnaire is a four-question screening instrument for alcoholism whose name is a mnemonic designating someone who has attempted to “cut down” on alcohol consumption, is “annoyed” by criticism of his or her drinking, feels “guilty,” and needs an “eye-opener” drink in the morning. The presence of two or more of these characteristics is considered indicative of an alcohol-use disorder. Body-mass index (the weight in kilograms divided by the square of the height in meters), number of chronic conditions (hypertension, diabetes, heart disease, chronic lung disease, cancer, arthritis, stroke, or difficulties with vision),17 and presence or absence of a change in overall health in the year before study entry were also included in all models.
Self-Reported Overall Health and Physical Difficulties
Self-reported overall health was assessed with the following question: “Would you say your health is excellent, very good, good, fair, or poor?” On the basis of participants' responses to this question in 1992 and 1996, we created the dichotomous outcome variable “major decline in self-reported health between 1992 and 1996,” defined as the presence or absence of either a decline from excellent, very good, or good health in 1992 to fair or poor health in 1996 or a decline from fair health in 1992 to poor health in 1996. We also analyzed the dichotomous outcome “any improvement in self-reported health.”
To assess changes in physical functioning, we used two sets of questions previously described by the Health and Retirement Study investigators.18 The four questions about mobility assess the ease or difficulty of activities requiring large-muscle strength, asking how difficult it is for the participant to walk several blocks, walk one block, climb one flight of stairs without resting, and climb several flights of stairs without resting. The six questions about agility assess the ease or difficulty of activities required to perform instrumental activities of daily living; they ask participants how difficult it is for them to sit for two hours, get up from a chair after sitting for long periods, lift or carry weights of more than 4.5 kg (10 lb), stoop, kneel, or crouch, pull or push a large object, and reach or extend their arms above the shoulder level.
Different options for the responses to the questions about physical functioning were used in 1992 and 1996. In 1992, the options were “not at all difficult,” “a little difficult,” “somewhat difficult,” and “very difficult or can't do.” In 1996, respondents were asked “Do you have any difficulty?” and were asked to choose among “no,” “yes,” and “can't do.” Because of these differences, we thought the most valid indicator of a change in health was the development of a new physical difficulty (i.e., a shift from “not at all difficult” in 1992 to a response of “yes” or “can't do” in 1996). We do not present data on improvements in physical functioning because a substantial proportion of these changes consisted of shifts from “a little difficult” in 1992 to “no” in 1996. Thus, an apparent improvement may not represent a true change in physical functioning but may instead be an effect of the 1996 response options, which did not encourage respondents to report minimal physical difficulties.
To identify participants in whom a new physical difficulty developed, all 1992 and 1996 questions were collapsed into dichotomous variables indicating no difficulty or some difficulty.19 Participants who said they had no difficulty with an activity in 1992 and then said they “did not do” an activity in 1996 (7.5 percent of participants for any item related to mobility and 6.0 percent for any item related to agility) were categorized as having a new physical difficulty.18 We based this categorization on the assumption that most persons 51 to 61 years old routinely perform the activities covered by the survey unless they have physical limitations, as well as on the empirical observation that the participants who said they “did not do” an activity had overall health that was similar to that of those who said they had difficulty. Finally, we created dichotomous outcome variables for both the questions about mobility and those about agility that indicated the presence or absence of a new physical difficulty with one or more activities.
Statistical Analysis
Analyses were conducted with the use of Stata statistical software (version 6, Stata, College Station, Tex.). All analyses were adjusted for the complex design of the survey and for the person-level analytic weights provided by the Health and Retirement Study. Bivariate analyses were conducted with the use of second-order corrected Pearson statistics for dichotomous variables20and adjusted Wald statistics for continuous variables.21 Multivariate analyses were conducted by means of logistic regression with adjustment for the covariates listed above. Because a decline could not occur and a new difficulty could not develop in participants who reported being in the worst possible state of health in 1992, the relevant analyses excluded the 360 participants (4.8 percent of the cohort) who were in poor health at base line, the 453 participants (6.0 percent) who had difficulties with four of the activities related to mobility, or the 236 participants (3.1 percent) who had difficulties with six activities related to agility. Conversely, 1798 participants who were in excellent health at base line (23.7 percent of the cohort) were excluded from the analysis of improvement in overall health. Odds ratios were converted to relative risks by means of published formulas.22
RESULTS
Of the 9824 participants between 51 and 61 years old who were interviewed in 1992, 1138 (11.6 percent) were lost to follow-up, 377 (3.8 percent) died, 665 (6.8 percent) were excluded from our study because they had public insurance in 1992, and 67 (0.7 percent) had missing data. Of the remaining 7577 participants, 6035 (79.6 percent) were continuously insured, 825 (10.9 percent) were intermittently uninsured, and 717 (9.5 percent) were continuously uninsured. The continuously uninsured and intermittently uninsured participants were more likely than the continuously insured participants to be women, nonwhite, and unmarried and had less education and a lower income (Table 1
TABLE 1
Base-Line Characteristics of the 7577 Participants.). The continuously or intermittently uninsured participants were also more likely to smoke, to have a history of problem drinking (i.e., two or more positive responses on the CAGE questionnaire), to be in fair or poor health, to have had a decline in health during the year before study entry, and to report more chronic medical conditions and physical difficulties.
Self-Reported Overall Health
Both the continuously and the intermittently uninsured participants were more likely to have a major decline in self-reported overall health between 1992 and 1996 than the continuously insured participants (21.6 percent, 16.1 percent, and 8.3 percent, respectively, of the three groups; P<0.001 for both comparisons) (Table 2
TABLE 2
Changes in Self-Reported Overall Health Status from 1992 to 1996.). After adjustment for other base-line characteristics, the continuously uninsured participants had a higher risk of a major decline in health than the continuously insured participants (adjusted relative risk, 1.63; 95 percent confidence interval, 1.26 to 2.08). The relative risk of a major decline in health for the continuously uninsured participants varied according to the base-line health status (Figure 1A
FIGURE 1
Estimated Adjusted Relative Risk (with 95 Percent Confidence Intervals) of a Major Decline in Overall Health (Panel A) and the Development of a New Difficulty with Mobility (Panel B) between 1992 and 1996 for Continuously Uninsured Participants as Compared with Continuously Insured Participants, According to Overall Health Status and the Number of Difficulties with Mobility at Base Line.), with the risk being greatest for those who were in excellent health at base line. The intermittently uninsured participants were also at higher risk for a major decline in health than the continuously insured participants (adjusted relative risk, 1.41; 95 percent confidence interval, 1.11 to 1.78) (Table 2). The relative risk for the uninsured participants was similar regardless of sex, race or ethnic background, and income (data not shown).
No comments:
Post a Comment