Dementia - Epidemiology of Aging: Racial/Ethnic Specifi c Disease Prevalence

Epidemiology of Aging: Racial/Ethnic Specifi c Disease Prevalence

8.3.6 Dementia

According to their 2015 Facts and Figures update, the Alzheimer’s Association esti- mates the prevalence rate of all-cause dementia in AAs to be about twice that of NHWs, and Hispanics’ to be about 50 % greater than NHWs, though comprehen- sive, national fi gures on prevalence and incidence are lacking for all-cause dementia as well as for specifi c types, such as Alzheimer’s Disease (AD). Steenland and colleagues performed a meta-analysis on six available studies reporting relative incidence rates of AD between AAs and Whites [ 73 ]. The results noted an aggregate relative risk increase of AD of 64 % for AAs as compared to Whites. Though fi ve out of the six included studies controlled for education level (in addition to other confounders), doing so may not have adequately controlled for differences in socioeconomic status. Moreover, four of these studies did not report Hispanic or non- Hispanic ethnicity, while two explicitly excluded those of Hispanic ethnicity. These signifi cant caveats aside, Steenland et al. estimated AD prevalence in the United States to be 5.5 % for Whites and 8.6 % for AAs among those aged 65–90 years [ 73 ]. In addition to higher incidence, part of the difference in prevalence stems from an apparent 20 % longer survival after diagnosis among AAs as compared to Whites, as well [ 73 , 74 ]. Mayeda and colleagues examined dementia incidence among patients of Kaiser Permanente Northern California, a diverse group aged 65 and older [ 75 ]. The group with highest age-adjusted dementia incidence was African- Americans (26.6 per 1000 person-years), followed by American Indians and Alaska Natives (22.2), followed by Pacifi c Islanders (19.6), Latinos (19.6), Whites (19.3), and Asian Americans (15.2 per 1000 person-years).

As for the causes of higher incidence of AD and all dementia among AAs, mul- tiple contributing factors may be at play. Some of those explored include higher rates of hypertension, obesity, and diabetes among AAs, all of which have been linked to Alzheimer’s risk [ 76 ]. Depression, chronic stress exposure, and lower levels of education have also been implicated [ 76 – 78 ]. Additionally, most diagnostic

instruments were devised in NHW populations, making their generalizability and accuracy suspect, especially among the less educated [ 79 ]. Campbell and colleagues identiﬁ ed that results of such instruments may even be interpreted differently along racial lines [ 80 ]. Though data is limited, there do not appear to be racial differences in burden of Alzheimer’s neuropathological ﬁ ndings at autopsy, as reviewed by Steenland et al. [ 73 ].

While allelic variants at several newly identiﬁ ed genes could explain some of the disparate risk of dementia between AAs and Whites [ 81 ], differences in the Apolipoprotein E ( APOE ) gene have received the greatest research focus. Across all populations, the APOE ε3 allele is most common, followed by ε4 and ε2 [ 82 , 83 ].

The ε4 allele has been found to convey increased risk of AD across racial/ethnic groups, while ε2 appears to be protective [ 82 , 83 ]. Debate continues regarding possible increased prevalence of the ε4 allele among AAs as compared to Whites. e ε4 allele is found with much greater frequency across sub-Saharan Africa and New Guinea, where a potential protective effect against plasmodium falciparum, suggested by in vitro data, could conceivably drive selection pressure relative to the other alleles [ 84 ].

Data on dementia prevalence and incidence in other American minority groups is even sparser and is generally limited to population-based studies. For example, Borenstein and colleagues measured incidence rates of all-cause dementia (14.4 per 1000 person-years), AD (11.3 per 1000 person-years), and vascular dementia (4.4 per 1000 person-years) among Japanese Americans 65 and older living in Seattle.

Probable and possible diagnoses were included, with AD and vascular dementia not mutually exclusive. Vascular dementia is also proposed to have higher prevalence among various Asian populations as compared to Whites [ 85 ]. A systematic review and meta-analysis of epidemiological studies compared dementia prevalence among Koreans, Western countries, and other Asian countries [ 86 ]. Dementia prevalence was found to be higher at 9.2 % in those over the age of 65 and represented a higher prevalence in those studies than that found in Western and other Asian countries.

We were unable to ﬁ nd any literature examining the prevalence of dementia among American Asian populations.

And among nearly 1800 Latinos 60 years and older residing in Sacramento Valley, California, Haan and colleagues found prevalence of all dementias to be 4.8 % with a 43 % attributable risk secondary to diabetes mellitus type 2, cerebro- vascular disease, or their combination [ 87 ]. This study included predominantly Mexican Americans, which does not represent the true diversity of Latinos in the United States. The ApoE ε4 allele was rare in this population, with a frequency of 4 %, though presence of ApoE ε4 did convey increased risk for dementia. Greater education and assimilation into general American culture (as assessed by the Acculturation Rating Scale for Mexican Americans) were both negatively associated with dementia risk. Remaining barriers in assessing dementia burden in these populations, as is the case with many other health conditions addressed in this chapter, include confounding by literacy, English language skills, access to medical care, and immigration status.

8.3.6.1 Diabetes

According to the CDC’s Diabetes Public Health Resource [ 88 ], overall prevalence of diabetes mellitus in 2014 was 21.5 % of Americans aged 65–74 years and 19.2 % among those 75 and older. These rates have increased steadily by over 100 %, respectively, since the early 1990s, while rates among younger adults have stabilized from 2009 to 2014. Among men 65–74 years old in 2014, Latinos had the highest prevalence (37.2 %) followed by AAs (29.6 %), Asians (22.5 %), and Whites (including Hispanic and non-Hispanic, 22.3 %). Prevalence among men 75 and older was highest in AAs (35.1 %) and lowest in Whites (20.9 %). As for women aged 65–74 years, AAs ranked highest (38.2 %), followed by Latinos (27.2 %), Whites (17.1 %), and Asians (14.0 %). Among women 75 and older, Latinos had the highest prevalence (29.1 %) and Asians the lowest (14.0 %). Of note, prevalence among Asian and Hispanic populations varies greatly by nation of origin, with Asian Indians having much higher rates than Koreans and Japanese, and Cubans having lower rates than Mexican Americans and Puerto Ricans [ 89 ].

Prevalence rates of diabetes remain higher for AAs and Latinos as compared to Whites. While some of these differences are attributed to traditional risk factors such as obesity, differences in effect size of such risk factors by race/ethnicity, as well as the presence of nontraditional risk factors, are the matter of great research interest. For instance, Kulick and colleagues found obesity in Whites to convey a 64 % increased risk of developing diabetes versus no signifi cant increased risk among AAs. And while smoking increased diabetes risk by 212 % in Whites, smoking status had a signifi cantly smaller effect in both AAs (22 % decreased risk versus AA nonsmokers) and Hispanics (21 % increased risk versus Hispanic nonsmokers) compared to Whites. While elevated C-reactive protein heralded increased risk of diabetes among Whites (by 66 %) and Hispanics (by 32 %), there was no effect on diabetes risk in AAs. Kulick et al. posited that, considering other authors’ fi ndings of increased prevalence of prediabetes among minority populations, the effects of the risk factors studied here might be greatly attenuated in populations with an already high risk for conversion to diabetes. Socioeconomic status is also a well- studied mediator of diabetes risk among minority populations, with Piccolo et al.

ﬁ nding that SES accounted for over 70 % of the difference in diabetes prevalence between AAs and Whites [ 90 ]. Additionally, Chatterjee and colleagues, in their interpretation of the ARIC Study data suggested that while 42 % of excess diabetes risk among AAs compared to Whites might be attributed to differences in traditional metabolic risk factors, newly identiﬁ ed risk factors might account for some 26 % of the remaining difference in risk: low forced vital capacity, low serum potas- sium, longest occupation held (a socioeconomic proxy), factor VIII: protein C ratio, and white blood cell count [ 91 ]. Potential mediators for the remaining, unexplained additional risk in AAs are being actively explored and include depression, dietary factors, vitamin D levels, physical activity, birth weight, gestational age at birth, levels of soluble receptors of advanced glycation end products, differences in glu- cose metabolism, visceral adiposity, and genetic variants [ 92 ].

Karter and colleagues conducted a retroactive, diagnosis-code-based study assessing for occurrence of diabetic complications in a 2-year period among over 115,000 Californians aged 60 years and older with diabetes mellitus who were insured by Kaiser Permanente [ 93 ]. In this cohort, 32 % overall had a diagnosis code submitted for any complication of diabetes during the 2-year period. Advanced diabetic eye disease was most common (21 % overall) followed by heart failure (13 %), while myocardial infarction, stroke, end-stage renal disease (ESRD), serious hypo- glycemia, and amputation all occurred in <2 % of participants. After adjustment for age, sex, diabetes type, duration of diabetes, therapies, and SES, AAs were found to have the greatest risk of severe eye complications (RR = 1.26 as compared to Whites, who had the lowest prevalence). Heart failure was most prevalent in Whites, AAs, and those of mixed race/ethnicity as compared to Asians, Latinos, and Filipinos.

ESRD was most common in Filipinos (RR = 2.61 compared to Whites) followed by AAs, Asians, Latinos, and those of mixed race/ethnicity. Absolute differences in amputations were quite small, but rates were signiﬁ cantly lower in Filipinos and Asians as compared to Whites. Myocardial infarction and stroke were both rare in this population, each occurring in about 1 % of participants during the 2-year fol- low- up interval. AAs had the lowest rate of myocardial infarction (RR = 0.52 compared to Whites) while Whites, Filipinos, and those of mixed race/ethnicity had the highest rates. Whites and those of mixed race/ethnicity had the highest rates of stroke compared to the other racial/ethnic groups.

Among a cohort of over 333,000 elderly Medicare Advantage patients with type 2 diabetes mellitus, Latinos (Odds ratio {OR} = 1.19 for men, 1.40 for women) and AAs (OR = 1.08 for men, 1.22 for women) of both sexes had signiﬁ cantly greater odds of higher cumulative burden of diabetic complications relative to gender- matched, NHWs [ 94 ]. Total health care costs were highest for Whites and were higher for females than males overall. Mayeda et al. investigated dementia incidence risk among an elderly diabetic cohort from the Kaiser Permanente Northern California Diabetes Registry between 1998 and 2007. After adjusting for age, Native Americans with diabetes were found to have the highest incidence (34 per 1000 person-years) followed by AAs (27), NHWs (25), Latinos (24), and Asians (19 per 1000 person-years).

Other investigators have found differences in prescribing practices, tolerability, and treatment response treatment response to diabetes medications along racial/

ethnic lines. Williams et al. found a much stronger hemoglobin A1c (A1c) lowering effect of metformin among AAs (0.90 % absolute reduction) compared to Whites (0.42 % absolute reduction) irrespective of baseline A1c [ 95 ]. Hazel-Fernandez and Xu and colleagues found that while 59 % of their participants remained on metformin therapy, predictors of discontinuing the same included female sex, AA race, Hispanic ethnicity, low-income subsidy eligibility, higher out-of-pocket medication cost, and depression [ 94 ]. Moreover, in a post hoc analysis culling together 1455 patients from 11 multinational clinical trials, Davidson and colleagues found dif- ferential effects of various insulin regimens along racial and ethnic lines: basal insulin therapy (as opposed to lispro mixtures) was associated with betterg glycemic

control in Latino patients as compared to Whites, and fewer Asians reached an A1c target of less than 7 % than did Whites [ 96 ].

Diabetic adults receiving care in a Patient-Centered Medical Home associated with the University of Pittsburgh were examined retrospectively for quality of care measures related to their receipt of diabetes care [ 97 ]. After adjusting for socioeconomic status and several other variables, AA patients were 43 % less likely to have A1c testing, 25 % less likely to receive inﬂ uenza vaccination, and 36 % less likely to achieve a blood pressure less than 140/90 mmHg. More AAs with elevated choles- terol were prescribed lipid-lowering therapy than were Whites, and yet AAs were 26 % less likely to achieve a low-density lipoprotein (LDL) target of less than 100 mg/dL. AA patients were younger, less likely to see an attending physician as their primary care provider, and had fewer endocrinology visits. Though there were no signiﬁ cant differences in number of classes of diabetes medications prescribed, AAs were slightly more likely to be treated with insulin than were Whites (32 % versus 28 %). Hooks-Anderson et al. found that among St. Louis, Missouri residents with average age 59, AA prediabetics and diabetics were more likely to be referred to diabetes educators than their White counterparts (prediabetics: 8.6 % versus 4 %;

diabetics: 16.8 % versus 13.6 %) [ 98 ]. The AA patients in this study had poorer glycemic control on average than did Whites. Finally, retrospective data from Chow and colleagues found signiﬁ cantly greater A1c reduction among Hispanics (1.1 % absolute reduction) given canagliﬂ ozin as compared to non-Hispanics (0.8 %), p = 0.043 [ 99 ]. Some of this difference may have been attributable to higher baseline A1c values in Hispanics in this sample.

8.3.6.2 Infl uenza/Pneumonia

The impact of infl uenza and pneumonia is fueled by two main factors, vaccination and preexisting disease. As discussed earlier, chronic respiratory disease, such as COPD, is a one of the top ten causes of death in all races for older adults. The infl u- ence of vaccinations is much more disparate. Vaccinations among all minorities have been shown to be lower than Whites. Singleton and colleagues examined a national population over the age of 65 for self-reported infl uenza vaccination and pneumococcal polysaccharide vaccinations (PPV); place of vaccination; and among the unvaccinated, main reasons for nonvaccination, awareness of vaccination, and receipt of provider recommendation for vaccination [ 100 ]. The results were notable for overall low vaccination rates, with rates at least 15 percentage points lower in AAs and Hispanics than in Whites for infl uenza and PPV [ 100 ]. In an analysis of the 2012 National Health Interview Survey for adult vaccinations, including infl uenza and pneumonia vaccinations, overall low coverage and racial disparities were found.

For those over the age of 65, 68.8 % of NHWs were covered for inﬂ uenza when compared to 53 % Blacks, 57.5 % Hispanics, 65.2 % Asians, and 56.5 % other races [ 101 ]. The analysis found even greater disparities for pneumococcal vaccinations with 64 % for Whites compared to 46.1 % for Blacks, 43.4 % for Hispanics, 41.3 % for Asians, and 44.7 % for other races [ 101 ].

Herbert and colleagues investigated differences in vaccinations among Medicare beneﬁ ciaries [ 102 ]. This studied explored resistant attitudes and beliefs about vaccination, poor access to care during times of vaccination, and discriminatory behav- ior by providers. Initiation of an encounter with a provider appeared to have the most impact on the disparity seed in vaccinations between Whites and AA and Hispanics. Resistant attitudes and beliefs contributed to poor vaccination rates in AAs and access to care was a low appeared to be minor contributors. The most common reason for resistance was a misperception that vaccination could cause inﬂ u- enza (white 18.0 %; AA 19.8 %, p > 0.20; Hispanic 8.5 %, p = 0.002) and an aversion to perceived side effects (white 15.4 %; AA 10.4 %, p > 0.20; Hispanic 5.9 %, p = 0.007).

Overall misperceptions about vaccination appear to be the greatest barrier to vaccination. It is probably these misperceptions that result in such poor initiation of provider visits for vaccination. This is especially concerning for those with preexisting pulmonary disease or other causes of immunocompromised.

8.3.6.3 Kidney Disease

According to the United States Renal Data System (USRDS), end-stage renal disease (ESRD) incidence ratios by race (AA, Native Americans, Asian/Paciﬁ c Islanders, and Hispanics compared to Whites) in 2013 were 3.0, 1.1, 1.2, and 2.4.

This is in the setting of a leveling and slightly declining incidence from a peak in 2006 [ 103 ]. However, the overall prevalence of ESRD continues to increase by approximately 21,000 cases a year. The prevalence of ESRD by race (AAs, Native Americans and Asians) compared to Whites is 3.7, 1.4, and 1.5 times, respectively.

These differences might have many causes including the cause of the ESRD and clinicians’ judgment of the cause is also variable. The USRDS also examined the incidence rate by age and noted that incidence up to age 44 had not changed over the last 20 years; however, incidence increased for those 45–74 and age 75 and older. Lastly age-adjusted incidence rates for those over age 65 had recently started to decline [ 103 ].

Despite the higher incidence rates of ESRD among racial and ethnic minorities, the incidence rates appear to have plateaued for AAs and Native Americans, while Asians and Whites continue to see increasing rates. Overall ESRD incidence rates have declined for the aforementioned racial/ethnic minorities and Native Americans have seen the greatest decline since 2000, moving from 2.6 to 1.1 presently [ 103 ].

There has been an increase of diabetes and hypertension as the primary cause of ESRD, while other causes such as glomerulonephritis and cystic kidney disease have either declined or stabilized [ 103 ]. The USRDS also found that diabetes as the primary cause of ESRD was higher for those 65 and older among Whites, AAs, and Hispanics; however, the rate was higher for AAs while it is more similar between Hispanics and Whites. Hypertension as the primary cause was higher among those 75 and older and highest among AAs at all ages with a notably 4 and three times higher rate compared to Whites for those aged 65–74 and 75 and older, respectively.

Treatment characteristics were also examined by USRDS [ 103 ]. Those over the age of 65 were noted to receive 12 or more months of nephrology pre-ESRD care at rates between 31.8 and 32.4 %. AAs and Hispanics were less likely to receive pre- ESRD nephrology care when compared to other races and non-Hispanics.

Hemodialysis, versus peritoneal dialysis and transplant, was more common, 90.3 and 94.1 % for those 65–74 and 75 and older, as a treatment modality compared to other age groups. AAs were least likely to receive a transplant, 1.1 % and Asians were most likely at 5.2 %.

Explanations for some of these differences include higher incidence of the primary causes of ESRD, including diabetes, hypertension, and glomerulonephritis [ 104 ].

Studies have found higher prevalence of focal segmental glomerulosclerosis, regard- less of Human Immunodeﬁ ciency (HIV) status, in AAs, lupus glomerulonephritis in AAs and Hispanics, and immunoglobulin A nephropathy in Whites and Asians [ 104 ].

The differences cannot be explained by the simply primary causes [ 103 , 104 ]. Genetic factors and health care-related factors are also implicated. As noted, treatment characteristics differ by race and might reﬂ ect differences in health care access, as well as trust and satisfaction with the health care that has been received.

8.3.6.4 HIV

HIV affects older adults and actually affects non-White populations less than Whites in this age range. According to the 2010 surveillance data from the Centers for Disease Control and Prevention, of an “estimated 47,500 new HIV infections in 2010, 5 % (2500) were among Americans aged 55 and older. Of these older Americans: 36 % (900) of new infections were in white men and 4 % (110) were in white women. 24 % (590) of new infections were in black men and 15 % (370) were in black women. 12 % (310) of new infections were in Hispanic/Latino men and 4 % (100) were in Hispanic/Latino women [ 105 ].” This difference remains, 67 % among Whites versus 16 % of Hispanics and 15 % of Blacks, when examining new HIV infections among men who have sex with men, who account for 44 % of new infections [ 105 ].

Although the risk is lower, the risk still exists among older racial and ethnic minorities. In addition, individuals may be less likely to seek diagnosis and treatment. The 2012 death rate per 1000 living with HIV was 13 % and 47 % higher in AAs than in Whites and Hispanics, respectively [ 106 ]. For individual over the age of 55 diagnosed with HIV, the death rate per 100,000 population and per 100,000 people living with HIV is similar, 41.8 and 41.3, respectively, only for AAs.

Hispanics’ death rate is 14.8 per 100,000 population and 31.5 per 100,000 people living with HIV and Whites’ death rates are 3.9 and 29.6. Although this demon- strates the disparity in deaths among older AAs, the HIV death rate among AAs decreased 28 % between 2008 and 2012 [ 106 ]. Studies indicate that 15 % of HIV- infected AAs are unaware of their infection compared to 12 % of Whites [ 106 ]. In all races, those over the age of 55 experienced the highest death rates and this is likely linked to longer duration of infection with HIV, greater accumulation of complications, and higher age-related all-cause mortality.

Dalam dokumen Lenise Cummings-Vaughn Dulce M. Cruz-Oliver Editors (Halaman 135-142)