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Who are the elderly who never receive influenza immunization?
Preventive Medicine 40 (2005) 469 – 478 www.elsevier.com/locate/ypmed
Who are the elderly who never receive influenza immunization? Usha Sambamoorthi, Ph.D.a,*, Patricia A. Findley, Dr.P.H., M.S.W., L.C.S.W.b a
Institute for Health, Health Care Policy, and Aging Research, Rutgers University, New Brunswick, NJ 08901, Unites States b Program for Disability Research, Rutgers University, New Brunswick, NJ 08901, United States Available online 18 September 2004
Abstract Objective. This paper estimates the rates of lifetime nonreceipt of influenza immunization among elderly and examines variations in the lifetime nonreceipt of immunization by gender, race and ethnic group, socioeconomic status, access to health care, and health status. Methods. Cross-sectional, nationally representative data on 5557 adults older than 50 years of age and living in the community from the 2000 Medical Expenditure Panel Survey are used. Lifetime nonreceipt of influenza immunization was analyzed with bivariate and multivariate statistical techniques. Findings. Thirty-one percent of the elderly reported never receiving influenza immunization and 20% reported irregular immunization. Higher odds of lifetime nonreceipt of vaccination and irregular vaccination were seen among African-Americans, young–old, current smokers, and those with no usual source of care. Conclusions. Future campaigns to increase immunization rates should be tailored to target this hard-to-reach group of individuals. D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. Keywords: Influenza immunization; MEPS; Elderly; Nonreceipt; Disparities
Introduction To reduce morbidity and mortality associated with influenza and pneumonia, the advisory committee on immunization practices recommends an annual influenza immunization for all adults 50 years of age and older [1,2]. To promote these guidelines, both Healthy People 2000 and Health People 2010 identified increasing the influenza and pneumococcal immunization levels [3,4]. For example, Healthy People 2010 identified increasing the influenza immunization rates to 90% and higher among high-risk individuals including those aged 65 years and older as one of its objectives (objective 14.29) [4]. A review of the Health People 2000 progress in this priority area revealed that in 1997, all but six states and the District of Columbia had met or exceeded that target with respect to influenza immunization. * Corresponding author. Institute for Health, Health Care Policy, and Aging Research, Rutgers University, 11 Bartram Road, Englishtown, NJ 07726. Fax: +1 732 972 1455. E-mail address: [email protected] (U. Sambamoorthi).
However, an evaluation of the progress in 2001 revealed that influenza immunization levels during 2000–2001 decreased from 1998 to 1999 levels in 27 of 52 reporting areas [5]. In addition, it is suggested that increases in self-reported coverage levels for influenza immunization may have reached a plateau and new strategies may be needed to increase the rates further [6]. While previous studies have shed some light on racial disparities [5,7–15], provider and patient attitudes [16–26], and access barriers [27–30] in immunizations among older adults, many of these studies have been restricted to analysis on whether the respondents received annual influenza immunization. Our study extends existing research by comparing individuals who never received influenza immunization to others who reported annual or irregular immunizations. Knowledge of who the abstainers are helps to focus immunization outreach efforts. In this study, we examine individuals aged older than 50 years who never received influenza immunization with data from the nationally representative sample of households in the US. We also examine variations in lifetime nonreceipt of influenza
0091-7435/$ - see front matter D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. doi:10.1016/j.ypmed.2004.07.017
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immunization by socioeconomic status, race and ethnicity, health status, chronic illness, and access to care. Our paper focuses on individuals starting at age 51 years and older rather than 65, because the age for universal influenza immunization has been lowered from 65 to 50 years and increasing immunization coverage for high-risk persons younger than 65 years is now a high priority for expanding influenza vaccine use [31,32].
Methods Study sample Our study sample is based on data from the household component of the 2000 Medical Expenditure Panel Survey. MEPS is a database of nationally representative data on health care use, expenditures, sources of payment, and insurance coverage for a non-institutionalized civilian population. Overall, the full 2000 MEPS sample consists of 9515 participating reporting units (where student RUs are linked to parent RUs for this count). These include 23,839 responding individuals that completed the full series of MEPS interviews for their entire period of eligibility, providing the necessary information to produce national use estimates for calendar year 2000. For each household, a designated informant answered all questions for the entire household. In addition, in the 2000 MEPS, a self-administered questionnaire (SAQ) was used to collect information on a variety of health status and health care quality measures of adults. The present analysis includes individuals older than 50 years of age in 2000. This age cut-off was selected because the US Preventive Services Task Force (USPSTF), the authoritative group on preventive services use, recommends routine annual immunization of adults 50 years and older [33]. We also excluded individuals with missing responses on the outcome variable with a final sample size of 5557 individuals living in the community. Measures Outcomes Influenza immunization. The MEPS respondents were asked about receiving the influenza vaccine (bAbout how long has it been since (person) had a flu shot?Q). It has to be noted that this question was administered to adults older than 17 years of age and who were alive as of the end of the year. The responses to this question were then coded as (1) bwithin past yearQ, (2) bwithin past 2 yearsQ, (3) bwithin past 3 yearsQ, (4) bwithin past 5 yearsQ, (5) bmore than 5 yearsQ, and (6) bneverQ. We excluded elderly with missing response (n = 147, 2.4%) on immunization status from the analysis. In our analysis, we combined response categories 2 through 5 and individuals falling in these categories were considered as inconsistent users of immunization. Thus, our outcome variable com-
prised of three categories: (1) receipt of immunization within the past year, (2) inconsistent receipt of immunization, and (3) never received immunization. Multivariate analysis predicted the log odds of never receiving influenza immunization and receiving immunization sometimes compared to receiving annual immunization. Independent variables Demographic variables consisted of gender, race or ethnicity, age, and marital status. We measured socioeconomic status through education and poverty level. Access to care included health insurance and usual source of health care. Health status was assessed with variables indicating perceived general health, mental health, and presence of depression and anxiety. We used the presence or absence of depressive symptoms as a control variable because there is some evidence that depressive symptoms affect self-care preventive practices [34–37]. Clinical practice guidelines of American Diabetes Association recommend that all individuals with diabetes should receive an influenza immunization annually [38]. Therefore, we included chronic conditions such as diabetes, asthma, and other chronic conditions as predictor variables. The number of healthy behaviors is an important measure of demand for preventive health services [39]. Therefore, we included smoking status and body mass index of the respondents as control variables. (Please see Appendix A for the definition of variables.) Statistical analyses Group differences in rates of influenza immunization were tested with chi-square statistics. To adjust for the problem of multiple comparisons, we used the Bonferroni test because it is very conservative. For the Bonferroni test, we simply divided each observed P value by the number of tests you perform. In general, group differences were considered significant only if the P values were less than or equal to 0.008. We employed multinomial logistic regression to examine factors associated with influenza immunization. In multinomial regression, the dependent variable bvaccinated with in the past yearQ was used as the reference category. In this regression, we included only those independent variables that were significant in the bivariate comparisons. All analyses used appropriate weights provided in the MEPS data to arrive at unbiased national estimates. Single personlevel weight variable SQPQW00F provided for use with the data obtained from the Self-Administered Questionnaire (SAQ) was used for the analyses of the current paper [40]. Sudaan software was used to adjust standard errors to account for the complex sampling design [41].
Findings Table 1 describes the elderly sample in 2000. The study sample consisted of 46% men and 54% women; 81% White,
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478 Table 1 Characteristics of elderly sample, Medical Expenditure Panel Survey, 2000
All Gender Male Female Race or Ethnicity White African-American Latino Other Age 51–64 65–79 80 and older Marital status Married Widowed Divorced or Separated Never married Education Less than HS HS Above HS Poverty status Poor Low income Middle income High income Employment status Employed Not employed Health insurance Military Private Public Uninsured Usual source of care PCP non-PCP Other None Health status Excellent or Very Good Good Fair or Poor Mental health Excellent or Very Good Good Fair or Poor Arthritis Yes No Cancer Yes No Emphysema Yes No Diabetes Yes No
Unweighted N
Weighted N
Weighted percentage
5557
71,814,924
100.0
2486 3071
32,854,473 38,960,452
45.8 54.3
3996 697 741 123
58,290,096 6,662,308 4,878,131 1,984,389
81.2 9.3 6.8 2.8
2946 1980 631
38,298,844 25,448,823 8,067,257
53.3 35.4 11.2
3488 1076 725 268
45,025,585 13,573,421 9,649,665 3,566,253
62.7 18.9 13.4 5.0
1549 1738 2143
16,776,394 23,725,217 30,102,614
23.8 33.6 42.6
974 780 1522 2281
9,873,105 9,651,484 21,250,304 31,040,031
13.8 13.4 29.6 43.2
2446 3111
32,841,214 38,973,710
45.7 54.3
107 3590 1457 403
1,342,918 48,970,935 17,284,558 4,216,514
1.9 68.2 24.1 5.9
2947 147 1,866 575
38,460,839 2,011,791 23,784,409 7,250,475
53.8 2.8 33.3 10.1
2564 1777 1216
34,856,794 22,563,519 14,394,611
48.5 31.4 20.0
3388 1617 552
44,933,738 20,150,372 6,730,815
62.6 28.1 9.4
168 5389
2,428,545 69,386,379
3.4 96.6
585 4972
7,863,357 63,951,567
11.0 89.1
335 5222
4,389,933 67,424,992
6.1 93.9
773 4784
8,965,184 62,849,741
12.5 87.5
471
Table 1 (continued)
Any heart disease Yes No Asthma Yes No Hypertension Yes No Stroke Yes No Depression or Anxiety Diagnosed Symptoms None Smoking status Current smoker No Desirable body weight Underweight Normal Over weight Obese Influenza immunization Within past year Within 2 years within 3 years within 5 years N5 years Never
Unweighted N
Weighted N
Weighted percentage
1151 4406
14,783,701 57,031,223
20.6 79.4
233 5324
2,954,813 68,860,111
4.1 95.9
2012 3545
25,075,444 46,739,480
34.9 65.1
149 5408
1,955,572 69,859,352
2.7 97.3
308 1614 3533
4,051,369 19,758,444 46,793,973
5.7 28.0 66.3
963 4517
12,632,660 58,237,757
17.8 82.2
90 1830 2054 1368
1,139,068 24,333,260 26,843,871 16,815,894
1.7 35.2 38.8 24.3
2676 574 113 59 330 1805
35,467,830 7,173,807 1,539,976 766,857 4,509,191 22,357,262
49.4 10.0 2.1 1.1 6.3 31.1
Note. Based on sampled adults aged older than 50 years and have no missing responses on the outcome variable.
9% African-American, 7% Latino, and 3% other. A majority (53%) was in the age group 51–64 years. Nearly two-thirds of the elderly were not married (63%). Only 24% had less than high school education, 14% were either poor or near poor, 6% had no health insurance, and 10% had no usual source of health care. An overwhelming majority of the elderly was in excellent or very good or good health (80%). Among chronic health conditions, hypertension was most prevalent (35%) followed by heart disease (21%) and diabetes (13%). Nearly one-third (34%) of the elderly had depression or anxiety disorders. Although most adults (70%) received influenza immunization (50% in the past year and 20% at some time), nearly one-third of adults (31%) never received influenza immunization (Table 2). We found substantial subgroup differences in receipt of immunization. Significantly higher proportion of Latinos (43%) and African-Americans (45%) than Whites (28%) had never received influenza immunization. The proportion of adults with nonreceipt of immunization decreased steadily and significantly with age from 43% among individuals aged 51–64 years to 13% among individuals in the age group 80 years and older. We did not observe significant and consistent group differences in the immunization rates by socioeconomic status.
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Table 2 Group differences in influenza immunization among elderly, Medical Expenditure Panel Survey, 2000 Unweighted N immunized All Gender Male Female Race or Ethnicity White African-American Latino Other Age 51–64 65–79 80 and older Marital status Married Widowed Divorced or Separated Never married Education Less than HS HS Above HS Poverty status Poor Low income Middle income High income Employment status Employed Not employed Health insurance Military Private Public Uninsured Usual source of care PCP non-PCP Other None Health status Excellent or Very Good Good Fair or Poor Mental health Excellent or Very Good Good Fair or Poor Arthritis Yes No Cancer Yes No Emphysema Yes No Diabetes Yes No
Weighted percent immunized
P value
Past year
Not past year
Never
Past year
Not past year
Never
2676
1076
1805
49.4
19.5
31.1
1141 1535
477 599
868 937
47.0 51.4
19.5 19.4
33.5 29.1
2110 223 291 52
765 160 129 22
1121 314 321 49
52.4 32.2 39.9 41.0
19.4 22.9 17.1 18.0
28.2 44.9 43.0 41.0
1014 1241 421
640 323 113
1292 416 97
35.3 64.6 68.4
22.3 15.6 18.5
42.5 19.7 13.1
1667 625 281 103
633 202 182 59
1188 249 262 106
48.7 61.0 40.5 38.3
18.2 18.2 25.8 23.2
33.1 20.9 33.6 38.5
757 829 1043
284 329 440
508 580 660
51.9 48.2 49.2
18.0 19.0 20.7
30.1 32.8 30.1
486 389 699 1102
193 147 302 434
295 244 521 745
51.7 53.6 50.3 46.7
19.5 18.5 20.1 19.3
28.8 27.9 29.6 33.9
899 1777
526 550
1021 784
38.0 59.0
21.7 17.6
40.3 23.4
48 1727 823 78
35 674 290 77
24 1189 344 248
45.0 48.2 60.1 20.4
32.3 19.2 18.7 21.7
22.7 32.6 21.2 57.9
1545 85 904 135
570 23 362 117
832 39 600 323
54.0 57.8 49.2 24.0
19.3 15.7 19.0 22.8
26.7 26.5 31.8 53.3
1130 878 668
508 333 235
926 566 313
44.8 50.8 58.4
20.2 19.1 18.3
35.1 30.0 23.3
1575 824 277
638 314 124
1175 479 151
47.2 53.1 53.1
19.1 19.8 21.1
33.7 27.1 25.8
101 2575
30 1046
37 1768
57.8 49.1
18.6 19.5
23.6 31.4
371 2305
106 970
108 1697
64.3 47.6
18.2 19.6
17.5 32.8
193 2483
67 1009
75 1730
57.7 48.8
20.7 19.4
21.5 31.8
467 2209
136 940
170 1635
61.8 47.6
17.5 19.8
20.8 32.6
0.0002
0.0000
0.0000
0.0000
0.0690
0.1244
0.0000
0.0000
0.0000
0.0000
0.0008
0.1109
0.0000
0.0011
0.0000
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478
473
Table 2 (continued) Unweighted N immunized Past year Any heart disease Yes No Asthma Yes No Hypertension Yes No Stroke Yes No Depression or Anxiety Diagnosed Symptoms None Smoking status Current smoker No Desirable body weight Underweight Normal Over weight Obese
Not past year
Weighted percent immunized
P value
Never
Past year
Not past year
Never 0.0000
725 1951
189 887
237 1568
64.1 45.6
16.1 20.4
19.7 34.1
153 2523
45 1031
35 1770
68.7 48.6
17.3 19.6
14.1 31.9
1123 1553
394 682
495 1310
57.9 44.8
19.1 19.7
23.0 35.5
105 2571
17 1059
27 1778
72.1 48.8
12.1 19.7
15.8 31.6
160 822 1645
72 304 686
76 488 1202
52.7 52.0 48.0
25.0 18.7 19.5
22.3 29.3 32.5
348 2291
212 851
403 1375
36.9 52.1
21.9 19.0
41.2 28.9
48 899 1006 623
12 339 396 286
30 592 652 459
52.8 49.2 50.8 47.1
11.5 18.9 19.7 20.7
35.8 31.9 29.5 32.2
0.0000
0.0000
0.0002
0.0005
0.0000
0.1503
Note. Based on sampled adults aged older than 50 years and have no missing responses on the outcome variable. P values are based on chi-square tests.
Access to health care as measured by insurance and usual source of care significantly influenced lifetime nonreceipt of influenza immunization. The rates were 27% for those who had usual source of care from their primary care physicians and 53% for those with no usual source of care. Uninsured adults were more likely to have never received immunization (58%) than those with private insurance (33%). A significantly higher proportion of healthy elderly (35%) reported to have never received influenza immunization than those in fair or poor health (23%). The same was true with respect to perceived mental health. With respect to chronic conditions, we found that a lower proportion of elderly with chronic illness such as heart disease and diabetes than others had never received immunization. Individuals with asthma were less likely to have never received immunization [42]. Adjusted effects on lifetime nonreceipt of immunization and immunization in the past compared to annual immunization are presented in Table 3. Here we used a conservative P value of 0.003 to assess significance. African-American race, usual source of health care, and current smoking status consistently predicted both never receiving immunization and receiving immunization irregularly. Controlling for socioeconomic characteristics, differences in access to care, and health status, African-American elderly were almost three times as likely as Whites to be in bnever immunizedQ category rather than in bimmunized within past yearQ group. Similarly, those who sought care from a primary care physician and other physicians were
less likely to have never received or irregularly receive immunizations. We found many factors affecting never receiving immunization rather than irregular immunization. For example, while the presence of health insurance predicted never receiving immunization, it did not predict irregular immunizations. Other factors that affected never receiving immunization only were Latino ethnicity, younger individuals in the age group 51–64 years of age, those with chronic conditions such as asthma, cancer, diabetes, and hypertension. Those with these chronic conditions were less likely to remain unvaccinated compare to elderly with out such chronic conditions.
Discussion Despite well-defined recommendations and efforts to vaccinate persons at high risk, our study found that nearly one-third of the elderly never received influenza immunization. Our reported rates of immunization in the past year are somewhat lower than those published in the literature [43] because of inclusion of younger cohort aged 51 and older. In addition, our study findings point to racial, financial, and personal barriers associated with receipt of influenza immunizations. Although our findings are consistent with those reported, the current study is significant in providing a snapshot from a recent time period and it focus individuals who never or irregularly receive immunization. This study also extends previous research by
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Table 3 Multinomial logistic regression on influenza immunization among the elderly, Medical Expenditure Panel Survey, 2000 Never received immunization Gender Male Female Race or Ethnicity White African-American Latino Other Age 51–64 65–79 80 and older Marital status Married Widowed Divorced or Separated Never married Employment status Employed Not employed Health insurance Military Private Public Uninsured Usual source of care PCP non-PCP Other None Health status Excellent or Very Good Good Fair or Poor Mental health Excellent or Very Good Good Fair or Poor Cancer Yes No Emphysema Yes No Diabetes Yes No Any heart disease Yes No Asthma Yes No Hypertension Yes No Stroke Yes No
Did not receive immunization in the past year
AOR
95% CI
P value
AOR
95% CI
P value
0.91
[0.80, 1.03]
0.1476
0.95
[0.8, 1.12]
0.5363
2.66 1.83 1.64
[1.99, 3.55] [1.36, 2.46] [1.00, 2.68]
0.0000 0.0001 0.0488
1.70 1.07 1.17
[1.25, 2.3] [0.75, 1.53] [0.71, 1.91]
0.0007 0.7088 0.5403
3.67 1.29
[2.51, 5.37] [0.93, 1.80]
0.0000 0.1304
1.69 0.79
[1.12, 2.55] [0.57, 1.11]
0.0123 0.1730
0.99 0.88 1.15
[0.80, 1.22] [0.69, 1.13] [0.76, 1.74]
0.9131 0.3148 0.5028
1.10 1.42 1.43
[0.87, 1.38] [1.14, 1.77] [0.92, 2.21]
0.4231 0.0022 0.1127
1.23
[1.03, 1.46]
0.0217
1.24
[1.01, 1.52]
0.0431
0.25 0.57 0.54
[0.12, 0.53] [0.38, 0.85] [0.37, 0.80]
0.0004 0.0065 0.0025
0.87 0.68 0.76
[0.46, 1.63] [0.45, 1.01] [0.48, 1.19]
0.6556 0.0559 0.2216
0.39 0.48 0.45
[0.27, 0.56] [0.26, 0.87] [0.31, 0.67]
0.0000 0.0166 0.0001
0.52 0.49 0.52
[0.37, 0.74] [0.28, 0.85] [0.37, 0.74]
0.0003 0.0117 0.0003
1.29 1.14
[1.00, 1.65] [0.88, 1.48]
0.0465 0.3144
1.28 1.08
[0.99, 1.66] [0.84, 1.39]
0.0611 0.5339
0.84 0.81
[0.60, 1.20] [0.59, 1.11]
0.3374 0.1826
0.73 0.86
[0.49, 1.07] [0.6, 1.24]
0.1073 0.4285
0.58
[0.45, 0.75]
0.0000
0.83
[0.64, 1.08]
0.1655
0.78
[0.55, 1.11]
0.1650
1.06
[0.74, 1.53]
0.7531
0.67
[0.51, 0.87]
0.0037
0.79
[0.6, 1.04]
0.0985
0.77
[0.62, 0.96]
0.0197
0.83
[0.67, 1.03]
0.0881
0.34
[0.22, 0.52]
0.0000
0.61
[0.4, 0.93]
0.0228
0.71
[0.60, 0.85]
0.0002
0.93
[0.77, 1.12]
0.4365
0.72
[0.37, 1.41]
0.3395
0.56
[0.25, 1.25]
0.1551
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475
Table 3 (continued) Never received immunization Depression or Anxiety Diagnosed Symptoms None Smoking status Current smoker No
Did not receive immunization in the past year
AOR
95% CI
P value
AOR
95% CI
P value
0.81 1.02
[0.57, 1.15] [0.84, 1.22]
0.2360 0.4223
1.18 0.91
[0.79, 1.76] [0.75, 1.11]
0.8652 0.3716
1.63
[1.33, 2.01]
0.0000
1.35
[1.08, 1.7]
0.0097
Note. Based on sampled adults aged older than 50 years and have no missing responses on the outcome variable. The reference category for outcome variable is receipt of influenza immunization in the past year. AOR: Adjusted Odds Radio. CI: Confidence Interval.
adding the subgroup of individuals, aged 50 through 64, who have been recently recommended by the USPSTF to receive routine annual immunization. This study adds to the growing body of literature that documents racial disparities in health care [44]. Even after controlling for socioeconomic status, the gaps in rates of immunization (never or inconsistent) between AfricanAmerican and Whites remained, suggesting that it is not the socioeconomic disadvantage that contributes to the lack of preventive care among racial minorities. It is possible that other barriers such as health literacy may influence the low rate of lifetime non-immunization. For example, it has been shown that after adjusting for demographics, education, income, physician visits, and health status, individuals with inadequate health literacy were more likely to report they had never received the influenza immunization [45]. Similarly, those who had not received influenza vaccine did not know of the need for influenza immunization and had misconceptions about its safety and efficacy [46]. Further research is needed to examine systematic racial differences in health literacy factors and their impact on nonreceipt of influenza immunization. We found that adults with usual source of care had higher rates of immunization compared to those without usual source of care. Furthermore, usual source of care affected whether an individual gets immunized in the past year or irregularly. These findings together highlight the crucial role of having a usual source of care as a bgatekeeperQ to facilitate and implement preventive medical care. An interesting finding of our study is that of those who were immunized, only 28% of the elderly did not receive immunization in the past year. In addition, other than AfricanAmerican race and usual source of care, there were no systematic variations in irregular immunizations. These findings suggest that targeting elderly who do not receive vaccination in the past year can increase influenza immunization. This suggestion is consistent with a randomized controlled study, which reported that interventions to increase coverage rates for influenza immunization had its greatest effort among the elderly who did not receive immunization in the past year [47]. Variations in inconsistent immunization may be attributable to attitudes that individuals hold [48]. Some may feel an
altruistic sense and feel that they should not take the immunization that may better serve an older person, particularly when shortages are publicized. While others may not feel that influenza is a significant enough concern for them so they forego the immunization. This may happen for several reasons including misunderstandings regarding the side effects (i.e., many feel the immunization makes them sicker than actually having influenza) and effectiveness of the immunization [46]. Many people forego immunizations just out of resistance to the pinch of the needle or lack of their own concerns for health promotion and cost associated with the immunization. Finally, convenience of access is another issue that may deter some individuals from receiving a immunization; making a trip to a doctor’s office by taking time away from work or family may be difficult for some and getting out of the home for an elderly person who may have functional limitations or an inability to drive may also compound access issues. Some limitations of our study need to be noted. We used self-reports for measuring immunizations, which may be subject to recall bias. In recent years, studies have assessed the sensitivity and specificity of patient self-report of influenza immunization [49,50,51,52,53]. A comparison of self-reported measures with chart data showed that respondents were more likely to overestimate annual influenza immunization [51]. However, other studies conclude that self-reports are highly sensitive and moderately specific for influenza vaccination [50,52]. Also, we did not control for type of insurance. For example, with the expansion of managed care, it is suggested that HMO enrollees were more likely than enrollees in indemnity plans to receive preventive services [54–56]. However, the effect of managed care on use of prevention services remains questionable. An updated literature review of 18 studies published between 1990 and 1998 did not provide consistent evidence that managed care plan enrollees are more likely than other enrollees to obtain preventive services [57]. Although recent studies show that among elderly managed care is associated with higher rates of influenza immunization for both Whites and African-Americans, racial disparities remain even under
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managed care [58]. Although we controlled for some indicators of healthy lifestyle, we did not control for indicators of healthy behaviors such as routine exercise that may affect use of preventive care [59]. Despite the limitations, our results do indicate that targeting a bcore groupQ of elderly who never receive immunization or who do not receive in the past year can improve immunization rates among elderly and thus help in achieving one of the goals of Healthy People 2010.
Appendix A (continued) Access to health care Insurance status
Access to health care Existing usual source of care
Acknowledgments The findings and opinions reported here are those of the authors and do not necessarily represent the views of any other individuals or organizations. Work for this grant was partially supported by the Rutgers’ NIMHfunded Center for Research on the Organization and Financing of Care for the Severely Mentally Ill, National Institutes of Mental Health, and Dr. Findley’s K23 Award under the National Institute of Child Health and Human Development.
Appendix A. (Table 4) Definitions of independent variables
Demographics Age
Race or ethnicity
Marital status
Socioeconomic status Family income
Education
Age as of December 2000 was determined. Because the effect of age is likely to be nonlinear, we also grouped age into 51–64, 65–79, and 80 years and older, with 80 and older as the reference group. Race or ethnicity was categorized as African-American, White, Latino, and others. In multivariate analysis, White was used axs the reference group. Marital status was classified as married, widowed, divorced or separated, and never married, with married as the comparison group.
MEPS included a family income variable, which was adjusted for marital status and expressed as a percentage of federal poverty guidelines. This variable consisted of four categories: (1) poor or near poor (less than 100% of federal poverty line), (2) low income, (3) middle income, and (4) high income (greater than or equal to 400% poverty line). Based on years, education was measured in three categories: no high school, high school, and above high school. In multivariate analysis above high school was used as the reference category.
Health status General health, mental health
Presence of depression or anxiety symptoms
We constructed a hierarchical grouping of insurance variable, consisting of five groups. These included private, military, Medicaid, Medicare, and other insurance. Military insurance included CHAMPUS/CHAMPVA. The MEPS sample adult respondent was asked whether each family member had a specific bdoctor’s office, clinic, health center, other place that (person) usually go if sick or needs advice about health?Q Positive responses were coded as indicating that the individual had a usual source of care. In addition, MEPS asked whether the provider is a person or facility. For providers designated as bpersonQ MEPS queried about provider specialty. Based on these three variables, we categorized source of care variable (1) no usual source of care, (2) care by primary care physician (PCP), (3) care by non-PCP, and (4) care by others. PCP care was defined if the provider was identified as a person and was in general or family practice, internal medicine, pediatrics, and obstetrics/gynecology. Care was considered as non-PCP care if the provider specialty was indicated as MD—other and MD—surgery. Other is a residual category that included facilities and nonmedical doctors such as nurse/nurse practitioners, physician’s assistant, chiropractors, and others as providers of care.
Self-assessed health was based on questions asking respondents to rate their general health on five point scales ranging from dexcellentT to dpoorT. We combined categories excellent and very good. Poor and fair were also combined to yield three groupings. In multivariate analyses, poor or fair was used as the reference group. A similarly constructed scale for perceived status of mental illness was used. Using responses from a question on whether the individual felt anxious or depressed, we constructed a binary variable to indicate presence or absence of depression and anxiety. We combined this variable with affective and anxiety disorders from medical conditions file to categorize individuals in to three groups: (1) with diagnosed anxiety or depression, (2) symptomatic depression/anxiety, and (3) none.
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478 Appendix A (continued) Presence of a chronic illness
Health behavior Smoking status
Body mass index
Respondents were asked whether a doctor had ever told them that they had medical problems related to heart, lung, or diabetes, and other conditions. Smoking variables consisted of two categories: current smoker versus others. The BMI was calculated as weight in kilograms divided by the square of height in meters from self-reported height and weight. We classified respondents as (1) underweight (BMI between b18.5%), (2) healthy normal weight (BMI between 18.5% and 24.9%), (3) overweight (BMI between 25% and 29.9%), and (4) obese (BMI greater than 30%).
[14]
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Who are the elderly who never receive influenza immunization? Usha Sambamoorthi, Ph.D.a,*, Patricia A. Findley, Dr.P.H., M.S.W., L.C.S.W.b a
Institute for Health, Health Care Policy, and Aging Research, Rutgers University, New Brunswick, NJ 08901, Unites States b Program for Disability Research, Rutgers University, New Brunswick, NJ 08901, United States Available online 18 September 2004
Abstract Objective. This paper estimates the rates of lifetime nonreceipt of influenza immunization among elderly and examines variations in the lifetime nonreceipt of immunization by gender, race and ethnic group, socioeconomic status, access to health care, and health status. Methods. Cross-sectional, nationally representative data on 5557 adults older than 50 years of age and living in the community from the 2000 Medical Expenditure Panel Survey are used. Lifetime nonreceipt of influenza immunization was analyzed with bivariate and multivariate statistical techniques. Findings. Thirty-one percent of the elderly reported never receiving influenza immunization and 20% reported irregular immunization. Higher odds of lifetime nonreceipt of vaccination and irregular vaccination were seen among African-Americans, young–old, current smokers, and those with no usual source of care. Conclusions. Future campaigns to increase immunization rates should be tailored to target this hard-to-reach group of individuals. D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. Keywords: Influenza immunization; MEPS; Elderly; Nonreceipt; Disparities
Introduction To reduce morbidity and mortality associated with influenza and pneumonia, the advisory committee on immunization practices recommends an annual influenza immunization for all adults 50 years of age and older [1,2]. To promote these guidelines, both Healthy People 2000 and Health People 2010 identified increasing the influenza and pneumococcal immunization levels [3,4]. For example, Healthy People 2010 identified increasing the influenza immunization rates to 90% and higher among high-risk individuals including those aged 65 years and older as one of its objectives (objective 14.29) [4]. A review of the Health People 2000 progress in this priority area revealed that in 1997, all but six states and the District of Columbia had met or exceeded that target with respect to influenza immunization. * Corresponding author. Institute for Health, Health Care Policy, and Aging Research, Rutgers University, 11 Bartram Road, Englishtown, NJ 07726. Fax: +1 732 972 1455. E-mail address: [email protected] (U. Sambamoorthi).
However, an evaluation of the progress in 2001 revealed that influenza immunization levels during 2000–2001 decreased from 1998 to 1999 levels in 27 of 52 reporting areas [5]. In addition, it is suggested that increases in self-reported coverage levels for influenza immunization may have reached a plateau and new strategies may be needed to increase the rates further [6]. While previous studies have shed some light on racial disparities [5,7–15], provider and patient attitudes [16–26], and access barriers [27–30] in immunizations among older adults, many of these studies have been restricted to analysis on whether the respondents received annual influenza immunization. Our study extends existing research by comparing individuals who never received influenza immunization to others who reported annual or irregular immunizations. Knowledge of who the abstainers are helps to focus immunization outreach efforts. In this study, we examine individuals aged older than 50 years who never received influenza immunization with data from the nationally representative sample of households in the US. We also examine variations in lifetime nonreceipt of influenza
0091-7435/$ - see front matter D 2004 The Institute For Cancer Prevention and Elsevier Inc. All rights reserved. doi:10.1016/j.ypmed.2004.07.017
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U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478
immunization by socioeconomic status, race and ethnicity, health status, chronic illness, and access to care. Our paper focuses on individuals starting at age 51 years and older rather than 65, because the age for universal influenza immunization has been lowered from 65 to 50 years and increasing immunization coverage for high-risk persons younger than 65 years is now a high priority for expanding influenza vaccine use [31,32].
Methods Study sample Our study sample is based on data from the household component of the 2000 Medical Expenditure Panel Survey. MEPS is a database of nationally representative data on health care use, expenditures, sources of payment, and insurance coverage for a non-institutionalized civilian population. Overall, the full 2000 MEPS sample consists of 9515 participating reporting units (where student RUs are linked to parent RUs for this count). These include 23,839 responding individuals that completed the full series of MEPS interviews for their entire period of eligibility, providing the necessary information to produce national use estimates for calendar year 2000. For each household, a designated informant answered all questions for the entire household. In addition, in the 2000 MEPS, a self-administered questionnaire (SAQ) was used to collect information on a variety of health status and health care quality measures of adults. The present analysis includes individuals older than 50 years of age in 2000. This age cut-off was selected because the US Preventive Services Task Force (USPSTF), the authoritative group on preventive services use, recommends routine annual immunization of adults 50 years and older [33]. We also excluded individuals with missing responses on the outcome variable with a final sample size of 5557 individuals living in the community. Measures Outcomes Influenza immunization. The MEPS respondents were asked about receiving the influenza vaccine (bAbout how long has it been since (person) had a flu shot?Q). It has to be noted that this question was administered to adults older than 17 years of age and who were alive as of the end of the year. The responses to this question were then coded as (1) bwithin past yearQ, (2) bwithin past 2 yearsQ, (3) bwithin past 3 yearsQ, (4) bwithin past 5 yearsQ, (5) bmore than 5 yearsQ, and (6) bneverQ. We excluded elderly with missing response (n = 147, 2.4%) on immunization status from the analysis. In our analysis, we combined response categories 2 through 5 and individuals falling in these categories were considered as inconsistent users of immunization. Thus, our outcome variable com-
prised of three categories: (1) receipt of immunization within the past year, (2) inconsistent receipt of immunization, and (3) never received immunization. Multivariate analysis predicted the log odds of never receiving influenza immunization and receiving immunization sometimes compared to receiving annual immunization. Independent variables Demographic variables consisted of gender, race or ethnicity, age, and marital status. We measured socioeconomic status through education and poverty level. Access to care included health insurance and usual source of health care. Health status was assessed with variables indicating perceived general health, mental health, and presence of depression and anxiety. We used the presence or absence of depressive symptoms as a control variable because there is some evidence that depressive symptoms affect self-care preventive practices [34–37]. Clinical practice guidelines of American Diabetes Association recommend that all individuals with diabetes should receive an influenza immunization annually [38]. Therefore, we included chronic conditions such as diabetes, asthma, and other chronic conditions as predictor variables. The number of healthy behaviors is an important measure of demand for preventive health services [39]. Therefore, we included smoking status and body mass index of the respondents as control variables. (Please see Appendix A for the definition of variables.) Statistical analyses Group differences in rates of influenza immunization were tested with chi-square statistics. To adjust for the problem of multiple comparisons, we used the Bonferroni test because it is very conservative. For the Bonferroni test, we simply divided each observed P value by the number of tests you perform. In general, group differences were considered significant only if the P values were less than or equal to 0.008. We employed multinomial logistic regression to examine factors associated with influenza immunization. In multinomial regression, the dependent variable bvaccinated with in the past yearQ was used as the reference category. In this regression, we included only those independent variables that were significant in the bivariate comparisons. All analyses used appropriate weights provided in the MEPS data to arrive at unbiased national estimates. Single personlevel weight variable SQPQW00F provided for use with the data obtained from the Self-Administered Questionnaire (SAQ) was used for the analyses of the current paper [40]. Sudaan software was used to adjust standard errors to account for the complex sampling design [41].
Findings Table 1 describes the elderly sample in 2000. The study sample consisted of 46% men and 54% women; 81% White,
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478 Table 1 Characteristics of elderly sample, Medical Expenditure Panel Survey, 2000
All Gender Male Female Race or Ethnicity White African-American Latino Other Age 51–64 65–79 80 and older Marital status Married Widowed Divorced or Separated Never married Education Less than HS HS Above HS Poverty status Poor Low income Middle income High income Employment status Employed Not employed Health insurance Military Private Public Uninsured Usual source of care PCP non-PCP Other None Health status Excellent or Very Good Good Fair or Poor Mental health Excellent or Very Good Good Fair or Poor Arthritis Yes No Cancer Yes No Emphysema Yes No Diabetes Yes No
Unweighted N
Weighted N
Weighted percentage
5557
71,814,924
100.0
2486 3071
32,854,473 38,960,452
45.8 54.3
3996 697 741 123
58,290,096 6,662,308 4,878,131 1,984,389
81.2 9.3 6.8 2.8
2946 1980 631
38,298,844 25,448,823 8,067,257
53.3 35.4 11.2
3488 1076 725 268
45,025,585 13,573,421 9,649,665 3,566,253
62.7 18.9 13.4 5.0
1549 1738 2143
16,776,394 23,725,217 30,102,614
23.8 33.6 42.6
974 780 1522 2281
9,873,105 9,651,484 21,250,304 31,040,031
13.8 13.4 29.6 43.2
2446 3111
32,841,214 38,973,710
45.7 54.3
107 3590 1457 403
1,342,918 48,970,935 17,284,558 4,216,514
1.9 68.2 24.1 5.9
2947 147 1,866 575
38,460,839 2,011,791 23,784,409 7,250,475
53.8 2.8 33.3 10.1
2564 1777 1216
34,856,794 22,563,519 14,394,611
48.5 31.4 20.0
3388 1617 552
44,933,738 20,150,372 6,730,815
62.6 28.1 9.4
168 5389
2,428,545 69,386,379
3.4 96.6
585 4972
7,863,357 63,951,567
11.0 89.1
335 5222
4,389,933 67,424,992
6.1 93.9
773 4784
8,965,184 62,849,741
12.5 87.5
471
Table 1 (continued)
Any heart disease Yes No Asthma Yes No Hypertension Yes No Stroke Yes No Depression or Anxiety Diagnosed Symptoms None Smoking status Current smoker No Desirable body weight Underweight Normal Over weight Obese Influenza immunization Within past year Within 2 years within 3 years within 5 years N5 years Never
Unweighted N
Weighted N
Weighted percentage
1151 4406
14,783,701 57,031,223
20.6 79.4
233 5324
2,954,813 68,860,111
4.1 95.9
2012 3545
25,075,444 46,739,480
34.9 65.1
149 5408
1,955,572 69,859,352
2.7 97.3
308 1614 3533
4,051,369 19,758,444 46,793,973
5.7 28.0 66.3
963 4517
12,632,660 58,237,757
17.8 82.2
90 1830 2054 1368
1,139,068 24,333,260 26,843,871 16,815,894
1.7 35.2 38.8 24.3
2676 574 113 59 330 1805
35,467,830 7,173,807 1,539,976 766,857 4,509,191 22,357,262
49.4 10.0 2.1 1.1 6.3 31.1
Note. Based on sampled adults aged older than 50 years and have no missing responses on the outcome variable.
9% African-American, 7% Latino, and 3% other. A majority (53%) was in the age group 51–64 years. Nearly two-thirds of the elderly were not married (63%). Only 24% had less than high school education, 14% were either poor or near poor, 6% had no health insurance, and 10% had no usual source of health care. An overwhelming majority of the elderly was in excellent or very good or good health (80%). Among chronic health conditions, hypertension was most prevalent (35%) followed by heart disease (21%) and diabetes (13%). Nearly one-third (34%) of the elderly had depression or anxiety disorders. Although most adults (70%) received influenza immunization (50% in the past year and 20% at some time), nearly one-third of adults (31%) never received influenza immunization (Table 2). We found substantial subgroup differences in receipt of immunization. Significantly higher proportion of Latinos (43%) and African-Americans (45%) than Whites (28%) had never received influenza immunization. The proportion of adults with nonreceipt of immunization decreased steadily and significantly with age from 43% among individuals aged 51–64 years to 13% among individuals in the age group 80 years and older. We did not observe significant and consistent group differences in the immunization rates by socioeconomic status.
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Table 2 Group differences in influenza immunization among elderly, Medical Expenditure Panel Survey, 2000 Unweighted N immunized All Gender Male Female Race or Ethnicity White African-American Latino Other Age 51–64 65–79 80 and older Marital status Married Widowed Divorced or Separated Never married Education Less than HS HS Above HS Poverty status Poor Low income Middle income High income Employment status Employed Not employed Health insurance Military Private Public Uninsured Usual source of care PCP non-PCP Other None Health status Excellent or Very Good Good Fair or Poor Mental health Excellent or Very Good Good Fair or Poor Arthritis Yes No Cancer Yes No Emphysema Yes No Diabetes Yes No
Weighted percent immunized
P value
Past year
Not past year
Never
Past year
Not past year
Never
2676
1076
1805
49.4
19.5
31.1
1141 1535
477 599
868 937
47.0 51.4
19.5 19.4
33.5 29.1
2110 223 291 52
765 160 129 22
1121 314 321 49
52.4 32.2 39.9 41.0
19.4 22.9 17.1 18.0
28.2 44.9 43.0 41.0
1014 1241 421
640 323 113
1292 416 97
35.3 64.6 68.4
22.3 15.6 18.5
42.5 19.7 13.1
1667 625 281 103
633 202 182 59
1188 249 262 106
48.7 61.0 40.5 38.3
18.2 18.2 25.8 23.2
33.1 20.9 33.6 38.5
757 829 1043
284 329 440
508 580 660
51.9 48.2 49.2
18.0 19.0 20.7
30.1 32.8 30.1
486 389 699 1102
193 147 302 434
295 244 521 745
51.7 53.6 50.3 46.7
19.5 18.5 20.1 19.3
28.8 27.9 29.6 33.9
899 1777
526 550
1021 784
38.0 59.0
21.7 17.6
40.3 23.4
48 1727 823 78
35 674 290 77
24 1189 344 248
45.0 48.2 60.1 20.4
32.3 19.2 18.7 21.7
22.7 32.6 21.2 57.9
1545 85 904 135
570 23 362 117
832 39 600 323
54.0 57.8 49.2 24.0
19.3 15.7 19.0 22.8
26.7 26.5 31.8 53.3
1130 878 668
508 333 235
926 566 313
44.8 50.8 58.4
20.2 19.1 18.3
35.1 30.0 23.3
1575 824 277
638 314 124
1175 479 151
47.2 53.1 53.1
19.1 19.8 21.1
33.7 27.1 25.8
101 2575
30 1046
37 1768
57.8 49.1
18.6 19.5
23.6 31.4
371 2305
106 970
108 1697
64.3 47.6
18.2 19.6
17.5 32.8
193 2483
67 1009
75 1730
57.7 48.8
20.7 19.4
21.5 31.8
467 2209
136 940
170 1635
61.8 47.6
17.5 19.8
20.8 32.6
0.0002
0.0000
0.0000
0.0000
0.0690
0.1244
0.0000
0.0000
0.0000
0.0000
0.0008
0.1109
0.0000
0.0011
0.0000
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478
473
Table 2 (continued) Unweighted N immunized Past year Any heart disease Yes No Asthma Yes No Hypertension Yes No Stroke Yes No Depression or Anxiety Diagnosed Symptoms None Smoking status Current smoker No Desirable body weight Underweight Normal Over weight Obese
Not past year
Weighted percent immunized
P value
Never
Past year
Not past year
Never 0.0000
725 1951
189 887
237 1568
64.1 45.6
16.1 20.4
19.7 34.1
153 2523
45 1031
35 1770
68.7 48.6
17.3 19.6
14.1 31.9
1123 1553
394 682
495 1310
57.9 44.8
19.1 19.7
23.0 35.5
105 2571
17 1059
27 1778
72.1 48.8
12.1 19.7
15.8 31.6
160 822 1645
72 304 686
76 488 1202
52.7 52.0 48.0
25.0 18.7 19.5
22.3 29.3 32.5
348 2291
212 851
403 1375
36.9 52.1
21.9 19.0
41.2 28.9
48 899 1006 623
12 339 396 286
30 592 652 459
52.8 49.2 50.8 47.1
11.5 18.9 19.7 20.7
35.8 31.9 29.5 32.2
0.0000
0.0000
0.0002
0.0005
0.0000
0.1503
Note. Based on sampled adults aged older than 50 years and have no missing responses on the outcome variable. P values are based on chi-square tests.
Access to health care as measured by insurance and usual source of care significantly influenced lifetime nonreceipt of influenza immunization. The rates were 27% for those who had usual source of care from their primary care physicians and 53% for those with no usual source of care. Uninsured adults were more likely to have never received immunization (58%) than those with private insurance (33%). A significantly higher proportion of healthy elderly (35%) reported to have never received influenza immunization than those in fair or poor health (23%). The same was true with respect to perceived mental health. With respect to chronic conditions, we found that a lower proportion of elderly with chronic illness such as heart disease and diabetes than others had never received immunization. Individuals with asthma were less likely to have never received immunization [42]. Adjusted effects on lifetime nonreceipt of immunization and immunization in the past compared to annual immunization are presented in Table 3. Here we used a conservative P value of 0.003 to assess significance. African-American race, usual source of health care, and current smoking status consistently predicted both never receiving immunization and receiving immunization irregularly. Controlling for socioeconomic characteristics, differences in access to care, and health status, African-American elderly were almost three times as likely as Whites to be in bnever immunizedQ category rather than in bimmunized within past yearQ group. Similarly, those who sought care from a primary care physician and other physicians were
less likely to have never received or irregularly receive immunizations. We found many factors affecting never receiving immunization rather than irregular immunization. For example, while the presence of health insurance predicted never receiving immunization, it did not predict irregular immunizations. Other factors that affected never receiving immunization only were Latino ethnicity, younger individuals in the age group 51–64 years of age, those with chronic conditions such as asthma, cancer, diabetes, and hypertension. Those with these chronic conditions were less likely to remain unvaccinated compare to elderly with out such chronic conditions.
Discussion Despite well-defined recommendations and efforts to vaccinate persons at high risk, our study found that nearly one-third of the elderly never received influenza immunization. Our reported rates of immunization in the past year are somewhat lower than those published in the literature [43] because of inclusion of younger cohort aged 51 and older. In addition, our study findings point to racial, financial, and personal barriers associated with receipt of influenza immunizations. Although our findings are consistent with those reported, the current study is significant in providing a snapshot from a recent time period and it focus individuals who never or irregularly receive immunization. This study also extends previous research by
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U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478
Table 3 Multinomial logistic regression on influenza immunization among the elderly, Medical Expenditure Panel Survey, 2000 Never received immunization Gender Male Female Race or Ethnicity White African-American Latino Other Age 51–64 65–79 80 and older Marital status Married Widowed Divorced or Separated Never married Employment status Employed Not employed Health insurance Military Private Public Uninsured Usual source of care PCP non-PCP Other None Health status Excellent or Very Good Good Fair or Poor Mental health Excellent or Very Good Good Fair or Poor Cancer Yes No Emphysema Yes No Diabetes Yes No Any heart disease Yes No Asthma Yes No Hypertension Yes No Stroke Yes No
Did not receive immunization in the past year
AOR
95% CI
P value
AOR
95% CI
P value
0.91
[0.80, 1.03]
0.1476
0.95
[0.8, 1.12]
0.5363
2.66 1.83 1.64
[1.99, 3.55] [1.36, 2.46] [1.00, 2.68]
0.0000 0.0001 0.0488
1.70 1.07 1.17
[1.25, 2.3] [0.75, 1.53] [0.71, 1.91]
0.0007 0.7088 0.5403
3.67 1.29
[2.51, 5.37] [0.93, 1.80]
0.0000 0.1304
1.69 0.79
[1.12, 2.55] [0.57, 1.11]
0.0123 0.1730
0.99 0.88 1.15
[0.80, 1.22] [0.69, 1.13] [0.76, 1.74]
0.9131 0.3148 0.5028
1.10 1.42 1.43
[0.87, 1.38] [1.14, 1.77] [0.92, 2.21]
0.4231 0.0022 0.1127
1.23
[1.03, 1.46]
0.0217
1.24
[1.01, 1.52]
0.0431
0.25 0.57 0.54
[0.12, 0.53] [0.38, 0.85] [0.37, 0.80]
0.0004 0.0065 0.0025
0.87 0.68 0.76
[0.46, 1.63] [0.45, 1.01] [0.48, 1.19]
0.6556 0.0559 0.2216
0.39 0.48 0.45
[0.27, 0.56] [0.26, 0.87] [0.31, 0.67]
0.0000 0.0166 0.0001
0.52 0.49 0.52
[0.37, 0.74] [0.28, 0.85] [0.37, 0.74]
0.0003 0.0117 0.0003
1.29 1.14
[1.00, 1.65] [0.88, 1.48]
0.0465 0.3144
1.28 1.08
[0.99, 1.66] [0.84, 1.39]
0.0611 0.5339
0.84 0.81
[0.60, 1.20] [0.59, 1.11]
0.3374 0.1826
0.73 0.86
[0.49, 1.07] [0.6, 1.24]
0.1073 0.4285
0.58
[0.45, 0.75]
0.0000
0.83
[0.64, 1.08]
0.1655
0.78
[0.55, 1.11]
0.1650
1.06
[0.74, 1.53]
0.7531
0.67
[0.51, 0.87]
0.0037
0.79
[0.6, 1.04]
0.0985
0.77
[0.62, 0.96]
0.0197
0.83
[0.67, 1.03]
0.0881
0.34
[0.22, 0.52]
0.0000
0.61
[0.4, 0.93]
0.0228
0.71
[0.60, 0.85]
0.0002
0.93
[0.77, 1.12]
0.4365
0.72
[0.37, 1.41]
0.3395
0.56
[0.25, 1.25]
0.1551
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478
475
Table 3 (continued) Never received immunization Depression or Anxiety Diagnosed Symptoms None Smoking status Current smoker No
Did not receive immunization in the past year
AOR
95% CI
P value
AOR
95% CI
P value
0.81 1.02
[0.57, 1.15] [0.84, 1.22]
0.2360 0.4223
1.18 0.91
[0.79, 1.76] [0.75, 1.11]
0.8652 0.3716
1.63
[1.33, 2.01]
0.0000
1.35
[1.08, 1.7]
0.0097
Note. Based on sampled adults aged older than 50 years and have no missing responses on the outcome variable. The reference category for outcome variable is receipt of influenza immunization in the past year. AOR: Adjusted Odds Radio. CI: Confidence Interval.
adding the subgroup of individuals, aged 50 through 64, who have been recently recommended by the USPSTF to receive routine annual immunization. This study adds to the growing body of literature that documents racial disparities in health care [44]. Even after controlling for socioeconomic status, the gaps in rates of immunization (never or inconsistent) between AfricanAmerican and Whites remained, suggesting that it is not the socioeconomic disadvantage that contributes to the lack of preventive care among racial minorities. It is possible that other barriers such as health literacy may influence the low rate of lifetime non-immunization. For example, it has been shown that after adjusting for demographics, education, income, physician visits, and health status, individuals with inadequate health literacy were more likely to report they had never received the influenza immunization [45]. Similarly, those who had not received influenza vaccine did not know of the need for influenza immunization and had misconceptions about its safety and efficacy [46]. Further research is needed to examine systematic racial differences in health literacy factors and their impact on nonreceipt of influenza immunization. We found that adults with usual source of care had higher rates of immunization compared to those without usual source of care. Furthermore, usual source of care affected whether an individual gets immunized in the past year or irregularly. These findings together highlight the crucial role of having a usual source of care as a bgatekeeperQ to facilitate and implement preventive medical care. An interesting finding of our study is that of those who were immunized, only 28% of the elderly did not receive immunization in the past year. In addition, other than AfricanAmerican race and usual source of care, there were no systematic variations in irregular immunizations. These findings suggest that targeting elderly who do not receive vaccination in the past year can increase influenza immunization. This suggestion is consistent with a randomized controlled study, which reported that interventions to increase coverage rates for influenza immunization had its greatest effort among the elderly who did not receive immunization in the past year [47]. Variations in inconsistent immunization may be attributable to attitudes that individuals hold [48]. Some may feel an
altruistic sense and feel that they should not take the immunization that may better serve an older person, particularly when shortages are publicized. While others may not feel that influenza is a significant enough concern for them so they forego the immunization. This may happen for several reasons including misunderstandings regarding the side effects (i.e., many feel the immunization makes them sicker than actually having influenza) and effectiveness of the immunization [46]. Many people forego immunizations just out of resistance to the pinch of the needle or lack of their own concerns for health promotion and cost associated with the immunization. Finally, convenience of access is another issue that may deter some individuals from receiving a immunization; making a trip to a doctor’s office by taking time away from work or family may be difficult for some and getting out of the home for an elderly person who may have functional limitations or an inability to drive may also compound access issues. Some limitations of our study need to be noted. We used self-reports for measuring immunizations, which may be subject to recall bias. In recent years, studies have assessed the sensitivity and specificity of patient self-report of influenza immunization [49,50,51,52,53]. A comparison of self-reported measures with chart data showed that respondents were more likely to overestimate annual influenza immunization [51]. However, other studies conclude that self-reports are highly sensitive and moderately specific for influenza vaccination [50,52]. Also, we did not control for type of insurance. For example, with the expansion of managed care, it is suggested that HMO enrollees were more likely than enrollees in indemnity plans to receive preventive services [54–56]. However, the effect of managed care on use of prevention services remains questionable. An updated literature review of 18 studies published between 1990 and 1998 did not provide consistent evidence that managed care plan enrollees are more likely than other enrollees to obtain preventive services [57]. Although recent studies show that among elderly managed care is associated with higher rates of influenza immunization for both Whites and African-Americans, racial disparities remain even under
476
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managed care [58]. Although we controlled for some indicators of healthy lifestyle, we did not control for indicators of healthy behaviors such as routine exercise that may affect use of preventive care [59]. Despite the limitations, our results do indicate that targeting a bcore groupQ of elderly who never receive immunization or who do not receive in the past year can improve immunization rates among elderly and thus help in achieving one of the goals of Healthy People 2010.
Appendix A (continued) Access to health care Insurance status
Access to health care Existing usual source of care
Acknowledgments The findings and opinions reported here are those of the authors and do not necessarily represent the views of any other individuals or organizations. Work for this grant was partially supported by the Rutgers’ NIMHfunded Center for Research on the Organization and Financing of Care for the Severely Mentally Ill, National Institutes of Mental Health, and Dr. Findley’s K23 Award under the National Institute of Child Health and Human Development.
Appendix A. (Table 4) Definitions of independent variables
Demographics Age
Race or ethnicity
Marital status
Socioeconomic status Family income
Education
Age as of December 2000 was determined. Because the effect of age is likely to be nonlinear, we also grouped age into 51–64, 65–79, and 80 years and older, with 80 and older as the reference group. Race or ethnicity was categorized as African-American, White, Latino, and others. In multivariate analysis, White was used axs the reference group. Marital status was classified as married, widowed, divorced or separated, and never married, with married as the comparison group.
MEPS included a family income variable, which was adjusted for marital status and expressed as a percentage of federal poverty guidelines. This variable consisted of four categories: (1) poor or near poor (less than 100% of federal poverty line), (2) low income, (3) middle income, and (4) high income (greater than or equal to 400% poverty line). Based on years, education was measured in three categories: no high school, high school, and above high school. In multivariate analysis above high school was used as the reference category.
Health status General health, mental health
Presence of depression or anxiety symptoms
We constructed a hierarchical grouping of insurance variable, consisting of five groups. These included private, military, Medicaid, Medicare, and other insurance. Military insurance included CHAMPUS/CHAMPVA. The MEPS sample adult respondent was asked whether each family member had a specific bdoctor’s office, clinic, health center, other place that (person) usually go if sick or needs advice about health?Q Positive responses were coded as indicating that the individual had a usual source of care. In addition, MEPS asked whether the provider is a person or facility. For providers designated as bpersonQ MEPS queried about provider specialty. Based on these three variables, we categorized source of care variable (1) no usual source of care, (2) care by primary care physician (PCP), (3) care by non-PCP, and (4) care by others. PCP care was defined if the provider was identified as a person and was in general or family practice, internal medicine, pediatrics, and obstetrics/gynecology. Care was considered as non-PCP care if the provider specialty was indicated as MD—other and MD—surgery. Other is a residual category that included facilities and nonmedical doctors such as nurse/nurse practitioners, physician’s assistant, chiropractors, and others as providers of care.
Self-assessed health was based on questions asking respondents to rate their general health on five point scales ranging from dexcellentT to dpoorT. We combined categories excellent and very good. Poor and fair were also combined to yield three groupings. In multivariate analyses, poor or fair was used as the reference group. A similarly constructed scale for perceived status of mental illness was used. Using responses from a question on whether the individual felt anxious or depressed, we constructed a binary variable to indicate presence or absence of depression and anxiety. We combined this variable with affective and anxiety disorders from medical conditions file to categorize individuals in to three groups: (1) with diagnosed anxiety or depression, (2) symptomatic depression/anxiety, and (3) none.
U. Sambamoorthi, P.A. Findley / Preventive Medicine 40 (2005) 469–478 Appendix A (continued) Presence of a chronic illness
Health behavior Smoking status
Body mass index
Respondents were asked whether a doctor had ever told them that they had medical problems related to heart, lung, or diabetes, and other conditions. Smoking variables consisted of two categories: current smoker versus others. The BMI was calculated as weight in kilograms divided by the square of height in meters from self-reported height and weight. We classified respondents as (1) underweight (BMI between b18.5%), (2) healthy normal weight (BMI between 18.5% and 24.9%), (3) overweight (BMI between 25% and 29.9%), and (4) obese (BMI greater than 30%).
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