Associations of infections and vaccines with Alzheimer's disease point to a role of compromised immunity rather than specific pathogen in AD

INTRODUCTION

Diverse pathogens (viral, bacterial, fungal) have been associated with Alzheimer's disease (AD) and related traits in various studies. This suggests that compromised immunity, rather than specific microbes, may play a role in AD by increasing an individual's vulnerability to various infections, which could contribute to neurodegeneration. If true, then vaccines that have heterologous effects on immunity, extending beyond protection against the targeted disease, may hold a potential for AD prevention.

METHODS

We evaluated the associations of common adult infections (herpes simplex, zoster (shingles), pneumonia, and recurrent mycoses), and vaccinations against shingles and pneumonia, with the risks of AD and other dementias in a pseudorandomized sample of the Health and Retirement Study (HRS).

RESULTS

Shingles, pneumonia and mycoses, diagnosed between ages 65 and 75, were all associated with significantly increased risk of AD later in life, by 16 %-42 %. Pneumococcal and shingles vaccines administered between ages 65-75 were both associated with a significantly lower risk of AD, by 15 %-21 %. These effects became less pronounced when AD was combined with other dementias.

DISCUSSION

Our findings suggest that both the pneumococcal polysaccharide vaccine and the live attenuated zoster vaccine can offer significant protection against AD. It remains to be determined if non-live shingles vaccine has a similar beneficial effect on AD. This study also found significant associations of various infections with the risk of AD, but not with the risks of other dementias. This indicates that vulnerability to infections may play a more significant role in AD than in other types of dementia, which warrants further investigation.

Associations of infections and vaccines with Alzheimer's disease point to a major role of compromised immunity rather than specific pathogen in AD

INTRODUCTION

Diverse pathogens (viral, bacterial, fungal) have been linked to Alzheimer's disease (AD) indicating a possibility that the culprit may be compromised immunity rather than particular microbe. If true, then vaccines with broad beneficial effects on immunity might be protective against AD.

METHODS

We estimated associations of common adult infections, including herpes simplex, zoster (shingles), pneumonia, and recurrent mycoses, as well as vaccinations against shingles and pneumonia, with the risk of AD in a pseudorandomized sample of the Health and Retirement Study.

RESULTS

Shingles, pneumonia, and mycoses diagnosed between ages 65-75, were all associated with higher risk of AD later in life, by 16%-42%. Pneumococcal and shingles vaccines received between ages 65-75 both lowered the risk of AD, by 15%-21%.

DISCUSSION

Our results support the idea that the connection between AD and infections involves compromised immunity rather than specific pathogen. We discuss mechanisms by which the declining immune surveillance may promote AD, and the role of biological aging in it. Repurposing of vaccines with broad beneficial effects on immunity could be a reasonable approach to AD prevention. Pneumococcal and zoster vaccines are promising candidates for such repurposing.

Differences in Risk of Alzheimer's Disease Following Later-Life Traumatic Brain Injury in Veteran and Civilian Populations

OBJECTIVE

To directly compare the effect of incident age 68+ traumatic brain injury (TBI) on the risk of diagnosis of clinical Alzheimer's disease (AD) in the general population of older adults, and between male veterans and nonveterans; to assess how this effect changes with time since TBI.

SETTING AND PARTICIPANTS

Community-dwelling traditional Medicare beneficiaries 68 years or older from the Health and Retirement Study (HRS).

DESIGN

Fine-Gray models combined with inverse-probability weighting were used to identify associations between incident TBI, post-TBI duration, and TBI treatment intensity, with a diagnosis of clinical AD dementia. The study included 16 829 older adults followed over the 1991-2015 period. For analyses of veteran-specific risks, 4281 veteran males and 3093 nonveteran males were identified. Analysis of veteran females was unfeasible due to the age structure of the population. Information on occurrence(s) of TBI, and onset of AD and risk-related comorbidities was constructed from individual-level HRS-linked Medicare claim records while demographic and socioeconomic risk factors were based on the survey data.

RESULTS

Later-life TBI was strongly associated with increased clinical AD risk in the full sample (pseudo-hazard ratio [HR]: 3.22; 95% confidence interval [CI]: 2.57-4.05) and in veteran/nonveteran males (HR: 5.31; CI: 3.42-7.94), especially those requiring high-intensity/duration care (HR: 1.58; CI: 1.29-1.91). Effect magnitude decreased with time following TBI (HR: 0.72: CI: 0.68-0.80).

CONCLUSION

Later-life TBI was strongly associated with increased AD risk, especially in those requiring high-intensity/duration care. Effect magnitude decreased with time following TBI. Univariate analysis showed no differences in AD risk between veterans and nonveterans, while the protective effect associated with veteran status in Fine-Gray models was largely due to differences in demographics, socioeconomics, and morbidity. Future longitudinal studies incorporating diagnostic procedures and documentation quantifying lifetime TBI events are necessary to uncover pathophysiological mediating and/or moderating mechanisms between TBI and AD.

Understanding Alzheimer's disease in the context of aging: Findings from applications of stochastic process models to the Health and Retirement Study

There is growing literature on applications of biodemographic models, including stochastic process models (SPM), to studying regularities of age dynamics of biological variables in relation to aging and disease development. Alzheimer's disease (AD) is especially good candidate for SPM applications because age is a major risk factor for this heterogeneous complex trait. However, such applications are largely lacking. This paper starts filling this gap and applies SPM to data on onset of AD and longitudinal trajectories of body mass index (BMI) constructed from the Health and Retirement Study surveys and Medicare-linked data. We found that APOE e4 carriers are less robust to deviations of trajectories of BMI from the optimal levels compared to non-carriers. We also observed age-related decline in adaptive response (resilience) related to deviations of BMI from optimal levels as well as APOE- and age-dependence in other components related to variability of BMI around the mean allostatic values and accumulation of allostatic load. SPM applications thus allow revealing novel connections between age, genetic factors and longitudinal trajectories of risk factors in the context of AD and aging creating new opportunities for understanding AD development, forecasting trends in AD incidence and prevalence in populations, and studying disparities in those.

Vaccination Against Pneumonia May Provide Genotype-Specific Protection Against Alzheimer's Disease

Vaccine repurposing that considers individual genotype may aid personalized prevention of Alzheimer's disease (AD). In this retrospective cohort study, we used Cardiovascular Health Study data to estimate associations of pneumococcal polysaccharide vaccine and flu shots received between ages 65-75 with AD onset at age 75 or older, taking into account rs6859 polymorphism in NECTIN2 gene (AD risk factor). Pneumococcal vaccine, and total count of vaccinations against pneumonia and flu, were associated with lower odds of AD in carriers of rs6859 A allele, but not in non-carriers. We conclude that pneumococcal polysaccharide vaccine is a promising candidate for genotype-tailored AD prevention.

Vulnerability to Hypertension Is a Major Determinant of Racial Disparities in Alzheimer's Disease Risk

BACKGROUND

Higher incidence levels of Alzheimer's disease (AD) in Black Americans are well documented. However, quantitative explanations of this disparity in terms of risk-factor diseases acting through well-defined pathways are lacking.

METHODS

We applied a Blinder-Oaxaca-based algorithm modified for censored data to a 5% random sample of Medicare beneficiaries age 65+ to explain Black/White disparities in AD risk in terms of differences in exposure and vulnerability to morbidity profiles based on 10 major AD-risk-related diseases.

RESULTS

The primary contribution to racial disparities in AD risk comes from morbidity profiles that included hypertension with about 1/5th of their contribution due to differences in prevalence (exposure effect) and 4/5ths to differences in the effects of the morbidity profile on AD risk (vulnerability effect). In total, disease-related effects explained a higher proportion of AD incidence in Black Americans than in their White counterparts.

CONCLUSIONS

Disease-related causes may represent some of the most straightforward targets for targeted interventions aimed at the reduction of racial disparities in health among US older adults. Hypertension is a manageable and potentially preventable condition responsible for the majority of the Black/White differences in AD risk, making mitigation of the role of this disease in engendering higher AD incidence in Black Americans a prominent concern.

Extended anesthesia exposure for abdominal and pelvic procedures in older adults with colorectal cancer: Associations with chart dementia diagnoses

BACKGROUND

We hypothesized that cumulative anesthesia exposure over the course of routine treatment of colorectal cancer in older adults can increase long-term risk of Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other chronic neurocognitive disorders (CND).

METHODS

We conducted a SEER-Medicare-based retrospective cohort study of 84,770 individuals age 65 years and older diagnosed with colorectal cancer between 1998 and 2007 using a proportional hazards model with inverse probability weighted estimators. The primary exploratory variable was a time-variant measure of cumulative anesthesia exposure for abdominal and pelvic procedures, updated continuously.

RESULTS

Our primary outcomes, AD and ADRD, occurred in 6005/84,770 (7.1%) and 14,414/83,444 (17.3%) individuals respectively. No statistically significant association was found between cumulative anesthesia exposure and AD (hazard ratio [HR], 0.993; 95% CI, 0.973-1.013). However, it was moderately associated with the risk of ADRD (HR, 1.016; 95% CI, 1.004-1.029) and some secondary outcomes including most notably: cerebral degeneration (HR, 1.048; 95% CI, 1.033-1.063), hepatic encephalopathy (HR, 1.133; 95% CI, 1.101-1.167), encephalopathy-not elsewhere classified (HR,1.095; 95% CI: 1.076-1.115), and incident/perioperative delirium (HR, 1.022; 95% CI, 1.012-1.032). Furthermore, we observed an association between perioperative delirium and increased risk of AD (HR, 2.05; 95% CI, 1.92-2.09).

CONCLUSION

Cumulative anesthesia exposure for abdominal and pelvic procedures was not associated with increased risk of AD directly and had a small but statistically significant association with ADRD and a number of other CNDs. Cumulative anesthesia exposure was also associated with perioperative delirium, which had an independent adverse association with AD risk.

Epidemiology of geographic disparities in heart failure among US older adults: a Medicare-based analysis

BACKGROUND

There are prominent geographic disparities in the life expectancy (LE) of older US adults between the states with the highest (leading states) and lowest (lagging states) LE and their causes remain poorly understood. Heart failure (HF) has been proposed as a major contributor to these disparities. This study aims to investigate geographic disparities in HF outcomes between the leading and lagging states.

METHODS

The study was a secondary data analysis of HF outcomes in older US adults aged 65+, using Center for Disease Control and Prevention sponsored Wide-Ranging Online Data for Epidemiologic Research (CDC WONDER) database and a nationally representative 5% sample of Medicare beneficiaries over 2000-2017. Empiric estimates of death certificate-based mortality from HF as underlying cause of death (CBM-UCD)/multiple cause of death (CBM-MCD); HF incidence-based mortality (IBM); HF incidence, prevalence, and survival were compared between the leading and lagging states. Cox regression was used to investigate the effect of residence in the lagging states on HF incidence and survival.

RESULTS

Between 2000 and 2017, HF mortality rates (per 100,000) were higher in the lagging states (CBM-UCD: 188.5-248.6; CBM-MCD: 749.4-965.9; IBM: 2656.0-2978.4) than that in the leading states (CBM-UCD: 79.4-95.6; CBM-MCD: 441.4-574.1; IBM: 1839.5-2138.1). Compared to their leading counterparts, lagging states had higher HF incidence (2.9-3.9% vs. 2.2-2.9%), prevalence (15.6-17.2% vs. 11.3-13.0%), and pre-existing prevalence at age 65 (5.3-7.3% vs. 2.8-4.1%). The most recent rates of one- (77.1% vs. 80.4%), three- (59.0% vs. 60.7%) and five-year (45.8% vs. 49.8%) survival were lower in the lagging states. A greater risk of HF incidence (Adjusted Hazards Ratio, AHR [95%CI]: 1.29 [1.29-1.30]) and death after HF diagnosis (AHR: 1.12 [1.11-1.13]) was observed for populations in the lagging states. The study also observed recent increases in CBMs and HF incidence, and declines in HF prevalence, prevalence at age 65 and survival with a decade-long plateau stage in IBM in both leading and lagging states.

CONCLUSION

There are substantial geographic disparities in HF mortality, incidence, prevalence, and survival across the U.S.: HF incidence, prevalence at age 65 (age of Medicare enrollment), and survival of patients with HF contributed most to these disparities. The geographic disparities and the recent increase in incidence and decline in survival underscore the importance of HF prevention strategies.

Genome-wide analysis of genetic predisposition to common polygenic cancers

Lung, breast, prostate, and colorectal cancers are among the most common and fatal malignancies worldwide. They are mainly caused by multifactorial mechanisms and are genetically heterogeneous. We investigated the genetic architecture of these cancers through genome-wide association, pathway-based, and summary-based transcriptome-/methylome-wide association analyses using three independent cohorts. Our genome-wide association analyses identified the associations of 33 single-nucleotide polymorphisms (SNPs) at P < 5E - 06, of which 32 SNPs were not previously reported and did not have proxy variants within their ± 1 Mb flanking regions. Moreover, other polymorphisms mapped to their closest genes were not previously associated with the same cancers at P < 5E - 06. Our pathway enrichment analyses revealed associations of 32 pathways; mainly related to the immune system, DNA replication/transcription, and chromosomal organization; with the studied cancers. Also, 60 probes were associated with these cancers in our transcriptome-wide and methylome-wide analyses. The ± 1 Mb flanking regions of most probes had not attained P < 5E - 06 in genome-wide association studies. The genes corresponding to the significant probes can be considered as potential targets for further functional studies. Two genes (i.e., CDC14A and PMEL) demonstrated stronger evidence of associations with lung cancer as they had significant probes in both transcriptome-wide and methylome-wide association analyses. The novel cancer-associated SNPs and genes identified here would advance our understanding of the genetic heterogeneity of the common cancers.

Does the Chronic Stress of Everyday Discrimination or Race Itself Better Predict AD Onset Risk?

Using evidence from the Health and Retirement Study, we explore racial disparities in Alzheimer's Disease (AD) onset risk. From a stress process perspective, there is substantial evidence in the literature that everyday discrimination is a chronic strain for Black individuals that acts as a social determinant of illness. However, few studies have examined specific relationships between this social stressor, race, and AD onset risk. Using Cox Proportional Hazard Models, we examined racial differences in exposure and vulnerability to everyday discrimination. Findings suggest that everyday discrimination predicts AD onset risk, and Black individuals experience more frequent exposure to everyday discrimination as a chronic strain. However, contrary to the stress process model, Black respondents were not more vulnerable to the effect of everyday discrimination on AD onset risk. Racial bias from medical professionals during the diagnostic process and mortality selection bias may explain this effect. Overall, the results of this study provide further evidence that discrimination is a key factor in predicting AD while also considering that many racial minorities with high rates of this type of social stress may not receive an unbiased diagnosis and/or survive to late life to develop AD.

Epidemiology of Geographic Disparities of Myocardial Infarction Among Older Adults in the United States: Analysis of 2000-2017 Medicare Data

Background: There are substantial geographic disparities in the life expectancy (LE) across the U.S. with myocardial infarction (MI) contributing significantly to the differences between the states with highest (leading) and lowest (lagging) LE. This study aimed to systematically investigate the epidemiology of geographic disparities in MI among older adults.

Methods: Data on MI outcomes among adults aged 65+ were derived from the Center for Disease Control and Prevention-sponsored Wide-Ranging Online Data for Epidemiologic Research database and a 5% sample of Medicare Beneficiaries for 2000–2017. Death certificate-based mortality from MI as underlying/multiple cause of death (CBM-UCD/CBM-MCD), incidence-based mortality (IBM), incidence, prevalence, prevalence at age 65, and 1-, 3-, and 5-year survival, and remaining LE at age 65 were estimated and compared between the leading and lagging states. Cox model was used to investigate the effect of residence in the lagging states on MI incidence and survival.

Results: Between 2000 and 2017, MI mortality was higher in the lagging than in the leading states (per 100,000, CBM-UCD: 236.7–583.7 vs. 128.2–357.6, CBM-MCD: 322.7–707.7 vs. 182.4–437.7, IBM: 1330.5–1518.9 vs. 1003.3–1197.0). Compared to the leading states, lagging states had higher MI incidence (1.1–2.0% vs. 0.9–1.8%), prevalence (10.2–13.1% vs. 8.3–11.9%), pre-existing prevalence (2.5–5.1% vs. 1.4–3.6%), and lower survival (70.4 vs. 77.2% for 1-year, 63.2 vs. 67.2% for 3-year, and 52.1 vs. 58.7% for 5-year), and lower remaining LE at age 65 among MI patients (years, 8.8–10.9 vs. 9.9–12.8). Cox model results showed that the lagging states had greater risk of MI incidence [Adjusted hazards ratio, AHR (95% Confidence Interval, CI): 1.18 (1.16, 1.19)] and death after MI diagnosis [1.22 (1.21, 1.24)]. Study results also showed alarming declines in survival and remaining LE at age 65 among MI patients.

Conclusion: There are substantial geographic disparities in MI outcomes, with lagging states having higher MI mortality, incidence, and prevalence, lower survival and remaining LE at age 65. Disparities in MI mortality in a great extent could be due to between-the-state differences in MI incidence, prevalence at age 65 and survival. Observed declines in survival and remaining LE require an urgent analysis of contributing factors that must be addressed.

Interactions Between Genes From Aging Pathways May Influence Human Lifespan and Improve Animal to Human Translation

A major goal of aging research is identifying genetic targets that could be used to slow or reverse aging - changes in the body and extend limits of human lifespan. However, majority of genes that showed the anti-aging and pro-survival effects in animal models were not replicated in humans, with few exceptions. Potential reasons for this lack of translation include a highly conditional character of genetic influence on lifespan, and its heterogeneity, meaning that better survival may be result of not only activity of individual genes, but also gene-environment and gene-gene interactions, among other factors. In this paper, we explored associations of genetic interactions with human lifespan. We selected candidate genes from well-known aging pathways (IGF1/FOXO growth signaling, P53/P16 apoptosis/senescence, and mTOR/SK6 autophagy and survival) that jointly decide on outcomes of cell responses to stress and damage, and so could be prone to interactions. We estimated associations of pairwise statistical epistasis between SNPs in these genes with survival to age 85+ in the Atherosclerosis Risk in Communities study, and found significant (FDR < 0.05) effects of interactions between SNPs in IGF1R, TGFBR2, and BCL2 on survival 85+. We validated these findings in the Cardiovascular Health Study sample, with P < 0.05, using survival to age 85+, and to the 90th percentile, as outcomes. Our results show that interactions between SNPs in genes from the aging pathways influence survival more significantly than individual SNPs in the same genes, which may contribute to heterogeneity of lifespan, and to lack of animal to human translation in aging research.

Analysis of Time Trends in Alzheimer's Disease and Related Dementias Using Partitioning Approach

BACKGROUND

Understanding the dynamics of epidemiologic trends in Alzheimer's disease (AD) and related dementias (ADRD) and their epidemiologic causes is vital to providing important insights into reducing the burden associated with these conditions.

OBJECTIVE

To model the time trends in age-adjusted AD/ADRD prevalence and incidence-based mortality (IBM), and identify the main causes of the changes in these measures over time in terms of interpretable epidemiologic quantities.

METHODS

Trend decomposition was applied to a 5%sample of Medicare beneficiaries between 1991 and 2017.

RESULTS

Prevalence of AD was increasing between 1992 and 2011 and declining thereafter, while IBM increased over the study period with a significant slowdown in its rate of growth from 2011 onwards. For ADRD, prevalence and IBM increased through 2014 prior to taking a downwards turn. The primary determinant responsible for declines in prevalence and IBM was the deceleration in the increase and eventual decrease in incidence rates though changes in relative survival began to affect the overall trends in prevalence/IBM in a noticeable manner after 2008. Other components showed only minor effects.

CONCLUSION

The prevalence and IBM of ADRD is expected to continue to decrease. The directions of these trends for AD are not clear because AD incidence, the main contributing component, is decreasing but at a decreasing rate suggesting a possible reversal. Furthermore, emerging treatments may contribute through their effects on survival. Improving ascertainment of AD played an important role in trends of AD/ADRD over the 1991-2009/10 period but this effect has exhausted itself by 2017.

Geographic disparities in mortality from Alzheimer's disease and related dementias

OBJECTIVES

The regions with highest and lowest Alzheimer's disease (AD) mortality across the United States at state/county levels were identified and their contribution to the differences in total mortality rates between these regions was evaluated. The disease, disease group, sex, race/ethnicity, and place-of-death-related inter-region differences that engender the disparity in mortality were quantitatively described. The hypothesis that inter-regional differences in filling out death certificates are a major contributor to differences in AD mortality was tested.

DESIGN

Retrospective evaluation of death certificate data.

SETTING

The United States.

PARTICIPANTS

Deceased US residents, 1999-2018.

METHODS

Region-specific age-adjusted mortality rates and group-specific rate decomposition.

RESULTS

The county clusters with the highest and lowest AD mortality rates were in Washington (WA) and New York (NY), respectively, with other notable high-mortality clusters on the border of Tennessee, Georgia, and Alabama as well as in North Dakota and South Dakota. These patterns were stable over the 1999-2018 period. AD had the highest contribution to total mortality difference between WA and NY (156%, higher in WA), in contrast circulatory diseases had a contribution of comparable magnitude (154%) but were higher in NY. Differences in cause-of-death certificate coding, either through coding of non-AD dementias, or other conditions accompanying a potential AD death could not account for differences in AD mortality between NY and WA.

CONCLUSIONS

Inter-regional differences in filling out death certificates were not a major contributor to variation in AD mortality between the regions with the highest and lowest rates. The respective mitigation of the effects of neural and circulatory diseases and several other high-impact conditions would not negate the disparity in mortality between NY and WA.

Chemotherapy and the Risk of Alzheimer's Disease in Colorectal Cancer Survivors: Evidence From the Medicare System

PURPOSE

Evidence on the nature of the relationship between patients receiving chemotherapy as an essential part of guideline-concordant cancer care and the onset of Alzheimer's Disease (AD) and other adverse cognitive outcomes has been mixed. Biological mechanisms were proposed to support both a potentially beneficial and an adverse role. To explore the relationship between chemotherapy and onset of AD and other neurocognitive disorders (ND) in colorectal cancer survivors.

METHODS

We conducted a retrospective cohort study of 135,834 individuals older than 65 years diagnosed with colorectal cancer between 1998 and 2007, using SEER-Medicare data. A proportional hazards model was used before and after the use of inverse probability weighting to account for populational differences between the chemotherapy and nonchemotherapy groups. Weights were normalized to the total sample size.

RESULTS

After inverse probability weighting, chemotherapy was associated with decreased AD risk (hazard ratio [HR]: 0.791; 95% CI: 0.758 to 0.824) and lower risk for the majority of other ND including AD-related diseases (HR: 0.823; CI: 0.802 to 0.844), dementia (permanent mental disorder) (HR: 0.807; CI: 0.782 to 0.832), and dementia (senile) (HR: 0.772; CI: 0.745 to 0.801). The only adverse effect to remain significant was cerebral degeneration (excluding AD) (HR: 1.067; CI: 1.033 to 1.102). The effects for AD remained after treatment was stratified by chemotherapy agent type and remained significant for up to 6 years past diagnosis.

CONCLUSION

Chemotherapy use in colorectal cancer survivors demonstrated an association with reduced risk for AD and other ND.

Roles of interacting stress-related genes in lifespan regulation: insights for translating experimental findings to humans

AIM

Experimental studies provided numerous evidence that caloric/dietary restriction may improve health and increase the lifespan of laboratory animals, and that the interplay among molecules that sense cellular stress signals and those regulating cell survival can play a crucial role in cell response to nutritional stressors. However, it is unclear whether the interplay among corresponding genes also plays a role in human health and lifespan.

METHODS

Literature about roles of cellular stressors have been reviewed, such as amino acid deprivation, and the integrated stress response (ISR) pathway in health and aging. Single nucleotide polymorphisms (SNPs) in two candidate genes (GCN2/EIF2AK4 and CHOP/DDIT3) that are closely involved in the cellular stress response to amino acid starvation, have been selected using information from experimental studies. Associations of these SNPs and their interactions with human survival in the Health and Retirement Study data have been estimated. The impact of collective associations of multiple interacting SNP pairs on survival has been evaluated, using a recently developed composite index: the SNP-specific Interaction Polygenic Risk Score (SIPRS).

RESULTS

Significant interactions have been found between SNPs from GCN2/EIF2AK4 and CHOP/DDI3T genes that were associated with survival 85+ compared to survival between ages 75 and 85 in the total sample (males and females combined) and in females only. This may reflect sex differences in genetic regulation of the human lifespan. Highly statistically significant associations of SIPRS [constructed for the rs16970024 (GCN2/EIF2AK4) and rs697221 (CHOP/DDIT3)] with survival in both sexes also been found in this study.

CONCLUSION

Identifying associations of the genetic interactions with human survival is an important step in translating the knowledge from experimental to human aging research. Significant associations of multiple SNPxSNP interactions in ISR genes with survival to the oldest old age that have been found in this study, can help uncover mechanisms of multifactorial regulation of human lifespan and its heterogeneity.

A medicare-based comparative mortality analysis of active surveillance in older women with DCIS

Over 97% of individuals diagnosed with ductal carcinoma in situ (DCIS) will choose to receive guideline concordant care (GCC), which was originally designed to treat invasive cancers and is associated with treatment related morbidity. An alternative to GCC is active surveillance (AS) where therapy is delayed until medically necessary. Differences in mortality risk between the two approaches in women age 65+ are analyzed in this study. SEER and Medicare information on treatment during the first year after diagnosis was used to identify three cohorts based on treatment type and timing: GCC (N = 21,772; immediate consent for treatment), AS1 (N = 431; delayed treatment within 365 days), and AS2 (N = 205; no treatment/ongoing AS). A propensity score-based approach provided pseudorandomization between GCC and AS groups and survival was then compared. Strong influence of comorbidities on the treatment received was observed for all age-groups, with the greatest burden observed in the AS2 group. All-cause and breast-cancer-specific mortality hazard ratios (HR) for AS1 were not statistically different from the GCC group; AS2 was associated with notably higher risk for both all-cause (HR:3.54; CI:3.29, 3.82) and breast-cancer-specific (HR:10.73; CI:8.63,13.35) mortality. Cumulative mortality was substantially higher from other causes than from breast cancer, regardless of treatment group. Women managed with AS for DCIS had higher all-cause and breast-cancer-specific mortality. This effect declined after accounting for baseline comorbidities. Delays of up to 12 months in initiation of GCC did not underperform immediate surgery.

Outcomes and Costs for Women After Breast Cancer: Preparing for Improved Survivorship of Medicare Beneficiaries

PURPOSE

Increasing health care costs, longer life expectancy, improved breast cancer (BC) survival, and higher levels of complex comorbidities have important implications for future Medicare expenditures.

METHODS

Data from the SEER program linked to Medicare claims records were used. Women with BC (cases) were categorized into 3 groups on the basis of their year of diagnosis (1998, 2003, or 2008) and were propensity score matched to women without a BC diagnosis (controls). All stage and stage-specific longitudinal changes in survival, morbidity levels using the Elixhauser index, and Medicare expenditures in 2018 dollars were calculated and compared.

RESULTS

More than 15% of BC cases were diagnosed in patients over the age of 85 years. The prevalence of most comorbidities increased over time. Costs among cases increased between 1998 and 2008. Spending directly correlated with the stage of disease at diagnosis, with the lowest per-patient costs in the ductal carcinoma in situ (DCIS) subgroup ($14,792 in 1998 and $19,652 in 2008) and the highest in those with distant cancer ($37,667 in 1998 and $43,675 in 2008). Assuming no significant changes in the distribution of BC stage or age at diagnosis, the total annual costs of caring for patients with BC in women 65 years of age or older at diagnosis increased by at least $1.1 billion between 1998 and 2008.

CONCLUSION

Improvements in BC survivorship are associated with intensive use of health care resources and substantially higher downstream costs among Medicare beneficiaries. Appropriate planning, in both the fiscal and the oncology care infrastructure, is required to prepare the health system for these emerging health care trends.

Longitudinal patterns of cost and utilization of medicare beneficiaries with bladder cancer

BACKGROUND

Bladder cancer (BC) is highly prevalent and costly. This study documented cost and use of services for BC care and for other (non-BC) care received over a 15-year follow-up period by a cohort of Medicare beneficiaries diagnosed with BC in 1998.

METHODS

Data came from the Surveillance, Epidemiology and End Results Program linked to Medicare claims. Medicare claims provided data on diagnoses, services provided, and Medicare Parts A and B payments. Cost was actual Medicare payments to providers inflated to 2018 US$. Cost and utilization were BC-related if the claim contained a BC diagnosis code. Otherwise, costs were for "other care." For utilization, we grouped Part B-covered services into 6 mutually-exclusive categories. Utilization rates were ratios of the count of claims in a particular category during a follow-up year divided by the number of beneficiaries with BC surviving to year-end.

RESULTS

Cumulatively over 15-years, for all stages combined, total BC-related cost per BC beneficiary was $42,011 (95% Confidence Interval (CI): $42,405-$43,417); other care cost was about twice this number. Cumulative total BC-related cost of 15-year BC survivors for all stages was $43,770 (CI: $39,068-$48,522), intensity of BC-related care was highest during the first year following BC diagnosis, falling substantially thereafter. After follow-up year 5, there were few statistically significant changes in BC-related utilization. Utilization of other care remained constant during follow-up or increased.

CONCLUSIONS

Substantial costs were incurred for non-BC care. While increasing BC survivorship is an important objective, non-BC care would remain a burden to Medicare.

Partitioning of time trends in prevalence and mortality of lung cancer

BACKGROUND

Time trends of lung cancer prevalence and mortality are the result of three competing processes: changes in the incidence rate, stage-specific survival, and ascertainment at early stages. Improvements in these measures act concordantly to improve disease-related mortality, but push the prevalence rate in opposite directions making a qualitative interpretation difficult. The goal of this paper is to evaluate the relative contributions of these components to changes in lung cancer prevalence and mortality.

METHODS

Partitioning of prevalence and mortality trends into their components using SEER data for 1973-2013.

RESULTS

The prevalence of lung cancer increases for females and decreases for males. In 1998, the former was due to increased incidence (45%-50% of total trend), improved survival (40%-45%), and increased ascertainment at early stages (10%-15%). In males, a rapidly declining incidence rate overpowered the effects of survival and ascertainment resulting in an overall decrease in prevalence over time. Trends in lung cancer mortality are determined by incidence during 1993-2002 with noticeable contribution of survival after 2002.

CONCLUSION

Lung cancer incidence was the main driving force behind trends in prevalence and mortality. Improved survival played essential role from 2000 onwards. Trends in stage ascertainment played a small but adverse role. Our results suggest that further improvement in lung cancer mortality can be achieved through advances in early stage ascertainment, especially for males, and that in spite of success in treatment, adenocarcinoma continues to exhibit adverse trends (especially in female incidence) and its role among other histology-specific lung cancers will increase in the near future.

Genetic heterogeneity of Alzheimer's disease in subjects with and without hypertension

Alzheimer's disease (AD) is a progressive neurodegenerative disorder caused by the interplay of multiple genetic and non-genetic factors. Hypertension is one of the AD risk factors that has been linked to underlying pathological changes like senile plaques and neurofibrillary tangles formation as well as hippocampal atrophy. In this study, we investigated the differences in the genetic architecture of AD between hypertensive and non-hypertensive subjects in four independent cohorts. Our genome-wide association analyses revealed significant associations of 15 novel potentially AD-associated polymorphisms (P < 5E-06) that were located outside the chromosome 19q13 region and were significant either in hypertensive or non-hypertensive groups. The closest genes to 14 polymorphisms were not associated with AD at P < 5E-06 in previous genome-wide association studies (GWAS). Also, four of them were located within two chromosomal regions (i.e., 3q13.11 and 17q21.2) that were not associated with AD at P < 5E-06 before. In addition, 30 genes demonstrated evidence of group-specific associations with AD at the false discovery rates (FDR) < 0.05 in our gene-based and transcriptome-wide association analyses. The chromosomal regions corresponding to four genes (i.e., 2p13.1, 9p13.3, 17q12, and 18q21.1) were not associated with AD at P < 5E-06 in previous GWAS. These genes may serve as a list of prioritized candidates for future functional studies. Our pathway-enrichment analyses revealed the associations of 11 non-group-specific and four group-specific pathways with AD at FDR < 0.05. These findings provided novel insights into the potential genetic heterogeneity of AD among subjects with and without hypertension.

Time trends in the prevalence of cancer and non-cancer diseases among older U.S. adults: Medicare-based analysis

Longer lifespan is accompanied by a larger number of chronic diseases among older adults. Because of a growing proportion of older adults in the U.S., this brings the problem of age-related morbidity to the forefront as a major contributor to rising medical expenditures. We evaluated 15-year time trends (from 1998 to 2013) in the prevalence of 48 acute and chronic non-cancer diseases and cancers in older U.S. adults aged 65+ and estimated the annual percentage changes of these prevalence trends using SEER-Medicare and HRS-Medicare data. We found that age-adjusted prevalence of cancers of kidney, pancreas, and melanoma, as well as diabetes, renal disease, limb fracture, depression, anemia, weight deficiency, dementia/Alzheimer's disease, drug/medications abuse and several other diseases/conditions increased over time. Conversely, prevalence of myocardial infarction, heart failure, cardiomyopathy, pneumonia/influenza, peptic ulcer, and gastrointestinal bleeding, among others, decreased over time. There are also diseases whose prevalence did not change substantially over time, e.g., a group of fast progressing cancers and rheumatoid arthritis. Analysis of trends of multiple diseases performed simultaneously within one study design with focus on the same time interval and the same population for all diseases allowed us to provide insight into the epidemiology of these conditions and identify the most alarming and/or unexpected trends and trade-offs. The obtained results can be used for health expenditures planning for growing sector of older adults in the U.S.

Identifying the causes of the changes in the prevalence patterns of diabetes in older U.S. adults: A new trend partitioning approach

AIMS

To identify how efforts to control the diabetes epidemic and the resulting changes in diabetes mellitus, type II (T2D) incidence and survival have affected the time-trend of T2D prevalence.

METHODS

A newly developed method of trend decomposition was applied to a 5% sample of Medicare administrative claims filed between 1991 and 2012.

RESULTS

Age-adjusted prevalence of T2D for adults age 65+ increased at an average annual percentage change of 2.31% between 1992 and 2012. Primary contributors to this trend were (in order of magnitude): improved survival at all ages, increased prevalence of T2D prior to age of Medicare eligibility, decreased incidence of T2D after age of Medicare eligibility.

CONCLUSIONS

Health services supported by the Medicare system, coupled with improvements in medical technology and T2D awareness efforts provide effective care for individuals age 65 and older. However, policy maker attention should be shifted to the prevention of T2D in younger age groups to control the increase in prevalence observed prior to Medicare eligibility.

Mortality and Macrovascular Risk in Elderly With Hypertension and Diabetes: Effect of Intensive Drug Therapy

BACKGROUND

This study identifies the effect of intensive drug therapy (IDT) in individuals age 65+ with diabetes (type 2 diabetes mellitus (T2D)) and hypertension on all-cause death, congestive heart failure (CHF), hospitalization for myocardial infarction (MI), and stroke or transient ischemic attack (TIA).

METHODS

Individuals from the Medicare 5% dataset with hypertension and T2D undergoing IDT for these conditions were propensity score matched to a nonintensive drug-therapy group. Hazard ratios (HRs) were obtained using the Cox proportional hazard model.

RESULTS

IDT was associated with increased risk of CHF (HR 2.32; 95% confidence interval (CI) 2.32-2.38), MI (HR 4.27; 95% CI 4.05-4.52), and stroke or TIA (HR 1.80; 95% CI 1.70-1.89) but decreased risk of death (HR 0.95; 95% CI 0.93-0.97). Risk for CHF (HR 0.73; 95% CI 0.71-0.73), MI (HR 0.64; 95% CI 0.62-0.67), stroke or TIA (HR 0.82; 95% CI 0.78-0.86), and death (HR 0.29; 95% CI 0.28-0.29) was decreased by adherence to diabetes management guidelines.

CONCLUSIONS

Use of IDT in a high-risk population delays death but not severe macrovascular outcomes. Protective effects of IDT in high-risk patients likely outweigh polypharmacy-related health concerns.

The Effect of Adherence to Screening Guidelines on the Risk of Alzheimer's Disease in Elderly Individuals Newly Diagnosed With Type 2 Diabetes Mellitus

Objective: The aim of this study was to examine the possibility that type 2 diabetes and Alzheimer's disease may share common behavioral protective factors such as adherence to type 2 diabetes treatment guidelines given that these two diseases have both epidemiological and metabolic similarities. Method: The method used in this study is a retrospective cohort study of 3,797 U.S. Medicare fee-for-service beneficiaries aged 66+ newly diagnosed with type 2 diabetes and without a prior record of Alzheimer's disease based on the Health and Retirement Study. Results: Results of a left-truncated Cox model showed that adherence reduces the risk of Alzheimer's disease by 20% to 24%. Other significant effects were college education (hazard ratio [HR]: 0.65; p value: .023), stroke (HR: 1.40; p value: .013), and 4+ limitations in physical functioning (HR: 1.33; p value: .008). Discussion: Risk of Alzheimer's disease can be reduced by behavioral factors. Possible mechanisms may include earlier start of interventions to reduce blood glucose levels and improve insulin sensitivity.

Time Trends in the Prevalence of Neurocognitive Disorders and Cognitive Impairment in the United States: The Effects of Disease Severity and Improved Ascertainment

BACKGROUND

Trends in the prevalence of cognitive impairment (CI) based on cognitive assessment instruments are often inconsistent with those of neurocognitive disorders (ND) based on Medicare claims records.

OBJECTIVE

We hypothesized that improved ascertainment and resulting decrease in disease severity at the time of diagnosis are responsible for this phenomenon.

METHODS

Using Medicare data linked to the Health and Retirement Study (1992-2012), we performed a joint analysis of trends in CI and ND to test our hypothesis.

RESULTS

We identified two major contributors to the divergent directions in CI and ND trends: reductions in disease severity explained more than 60% of the differences between CI and ND prevalence over the study period; the remaining 40% was explained by a decrease in the fraction of undiagnosed individuals.

DISCUSSION

Improvements in the diagnoses of ND diseases were a major contributor to reported trends in ND and CI. Recent forecasts of CI and ND trends in the U.S. may be overly pessimistic.

Theory of partitioning of disease prevalence and mortality in observational data

In this study, we present a new theory of partitioning of disease prevalence and incidence-based mortality and demonstrate how this theory practically works for analyses of Medicare data. In the theory, the prevalence of a disease and incidence-based mortality are modeled in terms of disease incidence and survival after diagnosis supplemented by information on disease prevalence at the initial age and year available in a dataset. Partitioning of the trends of prevalence and mortality is calculated with minimal assumptions. The resulting expressions for the components of the trends are given by continuous functions of data. The estimator is consistent and stable. The developed methodology is applied for data on type 2 diabetes using individual records from a nationally representative 5% sample of Medicare beneficiaries age 65+. Numerical estimates show excellent concordance between empirical estimates and theoretical predictions. Evaluated partitioning model showed that both prevalence and mortality increase with time. The primary driving factors of the observed prevalence increase are improved survival and increased prevalence at age 65. The increase in diabetes-related mortality is driven by increased prevalence and unobserved trends in time-periods and age-groups outside of the range of the data used in the study. Finally, the properties of the new estimator, possible statistical and systematical uncertainties, and future practical applications of this methodology in epidemiology, demography, public health and health forecasting are discussed.

Adherence to Guidelines for Screening and Medication Use: Mortality and Onset of Major Macrovascular Complications in Elderly Persons With Diabetes Mellitus

OBJECTIVE

The objective of this study is to investigate relationships between adherence to recommended screening and medication use and severe macrovascular complications and all-cause mortality among persons aged above 68 years with diabetes mellitus (DM).

METHOD

Data came from a 5% Medicare claims sample of beneficiaries initially diagnosed with DM during 2006-2008; follow-up was up to 7 years.

RESULTS

Adherence to screening guidelines led to reduced mortality-hazard ratio (HR) = 0.57, 95% confidence interval [CI] = [0.56, 0.58]; congestive heart failure [CHF], HR = 0.89, CI = [0.87, 0.91]; acute myocardial infarction [AMI], HR = 0.90, CI = [0.85, 0.95]; and stroke/transient ischemic attack [Stroke/TIA], HR = 0.92, CI = [0.87, 0.97]-during follow-up. Recommended medication use led to lower mortality: HR = 0.72, CI = [0.70, 0.73]; CHF, HR = 0.67, CI = [0.66, 0.69]; AMI, HR = 0.68, CI = [0.65, 0.71]; and Stroke/TIA, HR = 0.79, CI = [0.76, 0.83].

DISCUSSION

Elderly persons newly diagnosed with diabetes who adhered to recommended care experienced reduced risk of mortality and severe macrovascular complications.

Introducing Anti-Vascular Endothelial Growth Factor Therapies for AMD Did Not Raise Risk of Myocardial Infarction, Stroke, and Death

PURPOSE

To assess the effect of availability of anti-vascular endothelial growth factor (VEGF) therapy on mortality and hospitalizations for acute myocardial infarction (AMI) and stroke over a 5-year follow-up period in United States Medicare beneficiaries newly diagnosed with exudative age-related macular degeneration (AMD) in 2006 compared with control groups consisting of beneficiaries (1) newly diagnosed with exudative AMD at a time when anti-VEGF therapy was not possible and (2) newly diagnosed with nonexudative AMD.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Beneficiaries newly diagnosed with exudative and nonexudative AMD in 2000 and 2006 selected from a random longitudinal sample of Medicare 5% claims and enrollment files.

METHODS

Beneficiaries with a first diagnosis of exudative AMD in 2006 were the treatment group; beneficiaries newly diagnosed with exudative AMD in 2000 or nonexudative AMD in 2000 or 2006 were control groups. To deal with potential selection bias, we designed an intent-to-treat study, which controlled for nonadherence to prescribed regimens. The treatment group consisted of patients with clinically appropriate characteristics to receive anti-VEGF injections given that the therapy is available, bypassing the need to monitor whether treatment was actually received. Control groups consisted of patients with clinically appropriate characteristics but first diagnosed at a time when the therapy was unavailable (2000) and similar patients but for whom the therapy was not clinically indicated (2000, 2006). We used a Cox proportional hazard model.

MAIN OUTCOME MEASURES

All-cause mortality and hospitalization for AMI and stroke during follow-up.

RESULTS

No statistically significant changes in probabilities of death and hospitalizations for AMI and stroke within a 5-year follow-up period were identified in exudative AMD beneficiaries newly diagnosed in 2006, the beginning of widespread anti-VEGF use, compared with 2000. As an alternative to our main analysis, which excluded beneficiaries from nonexudative AMD group who received anti-VEGF therapies during follow-up, we performed a sensitivity analysis with this group of individuals reincluded (11% of beneficiaries newly diagnosed with nonexudative AMD in 2006). Results were similar.

CONCLUSIONS

Introduction of anti-VEGF agents in 2006 for treating exudative AMD has not posed a threat of increased risk of AMI, stroke, or all-cause mortality.

Screening for a Chronic Disease: A Multiple Stage Duration Model with Partial Observability

We estimate a dynamic multi-stage duration model to investigate how early detection of diabetes can delay the onset of lower extremity complications and death. We allow for partial observability of the disease stage, unmeasured heterogeneity, and endogenous timing of diabetes screening. Timely diagnosis appears important. We evaluate the effectiveness of two potential policies to reduce the monetary costs of frequent screening in terms of lost longevity. Compared to the status quo, the more restrictive policy yields an implicit value for an additional year of life of about $50,000, while the less restrictive policy implies a value of about $120,000.

Effect of Prior Anti-VEGF Injections on the Risk of Retained Lens Fragments and Endophthalmitis after Cataract Surgery in the Elderly

PURPOSE

To investigate the effect of prior intravitreal anti-vascular endothelial growth factor (VEGF) injections on surgical and postoperative complication rates associated with cataract surgery in a nationally representative longitudinal sample of elderly persons.

DESIGN

Retrospective, longitudinal cohort analysis.

PARTICIPANTS

A total of 203 643 Medicare beneficiaries who underwent cataract surgery from January 1, 2009, to December 31, 2013.

METHODS

By using the 5% sample of Medicare claims data, the study assessed risks of 3 adverse outcomes after receipt of cataract surgery for beneficiaries with a history of intravitreal injections. Risks of these outcomes in beneficiaries with a history of intravitreal injections relative to those without were calculated using the Cox proportional hazard model.

MAIN OUTCOME MEASURES

The primary outcome was the risk of subsequent removal of retained lens fragments (RLFs) within 28 days after cataract surgery. Secondary outcomes were a new diagnosis of acute (<40 days) or delayed-onset (40+ days) endophthalmitis and risk of a new primary open-angle glaucoma (POAG) diagnosis within 365 days after cataract surgery.

RESULTS

Prior intravitreal anti-VEGF injections were associated with a significantly increased risk of subsequent RLF removal within 28 days after cataract surgery (hazard ratio [HR], 2.26; 95% confidence interval [CI], 1.19-4.30). Prior injections were also associated with increased risk of both acute (HR, 2.29; 95% CI, 1.001-5.22) and delayed-onset endophthalmitis (HR, 3.65; 95% CI, 1.65-8.05). Prior injections were not a significant indicator of increased risk of a new POAG diagnosis.

CONCLUSIONS

A history of intravitreal injections may be a risk factor for cataract surgery-related intraoperative complications and endophthalmitis. Given the frequency of intravitreal injections and cataract surgery, increased preoperative assessment, additional intraoperative caution, and postoperative vigilance are recommended in patients with a history of intravitreal injections undergoing cataract extraction.

Adherence to diabetes guidelines for screening, physical activity and medication and onset of complications and death

AIMS

Analyze relationships between adherence to guidelines for diabetes care - regular screening; physical activity; and medication - and diabetes complications and mortality.

METHODS

Outcomes were onset of congestive heart failure (CHF), stroke, renal failure, moderate complications of lower extremities, lower-limb amputation, proliferative diabetic retinopathy (PDR), and mortality during follow-up. Participants were persons aged 65+ in the Health and Retirement Study (HRS) 2003 Diabetes Study and had Medicare claims in follow-up period (2004-8).

RESULTS

Adherence to screening recommendations decreased risks of developing CHF (odds ratio (OR)=0.83; 95% confidence interval (CI): 0.72-0.96), stroke (OR=0.80; 95% CI: 0.68-0.94); renal failure (OR=0. 82; 95% CI: 0.71-0.95); and death (OR=0.86; 95% CI: 0.74-0.99). Adherence to physical activity recommendation reduced risks of stroke (OR=0.64; 95% CI: 0.45-0.90), renal failure (OR=0.71; 95% CI: 0.52-0.97), moderate lower-extremity complications (OR=0.71; 95% CI: 0.51-0.99), having a lower limb amputation (OR=0.31, 95% CI: 0.11-0.85), and death (OR=0.56, 95% CI: 0.41-0.77). Medication adherence was associated with lower risks of PDR (OR=0.35, 95% CI: 0.13-0.93).

CONCLUSIONS

Adherence to screening, physical activity and medication guidelines was associated with lower risks of diabetes complications and death. Relative importance of adherence differed among outcome measures.

Gaps in receipt of regular eye examinations among medicare beneficiaries diagnosed with diabetes or chronic eye diseases

OBJECTIVE

To examine a wide range of factors associated with regular eye examination receipt among elderly individuals diagnosed with glaucoma, age-related macular degeneration, or diabetes mellitus (DM).

DESIGN

Retrospective analysis of Medicare claims linked to survey data from the Health and Retirement Study (HRS).

PARTICIPANTS

The sample consisted of 2151 Medicare beneficiaries who responded to the HRS.

METHODS

Medicare beneficiaries with ≥ 1 of the 3 study diagnoses were identified by diagnosis codes and merged with survey information. The same individuals were followed for 5 years divided into four 15-month periods. Predictors of the number of periods with an eye examination evaluated were beneficiary demographic characteristics, income, health, cognitive and physical function, health behaviors, subjective beliefs about longevity, the length of the individual's financial planning horizon, supplemental health insurance coverage, eye disease diagnoses, and low vision/blindness at baseline. We performed logit analysis of the number of 15-month periods in which beneficiaries received an eye examination.

MAIN OUTCOME MEASURES

The primary outcome measure was the number of 15-month periods with an eye examination.

RESULTS

One third of beneficiaries with the study's chronic diseases saw an eye care provider in all 4 follow-up periods despite having Medicare. One quarter only obtained an eye examination at most during 1 of the four 15-month follow-up periods. Among the 3 groups of patients studied, utilization was particularly low for persons with diagnosed DM and no eye complications. Age, marriage, education, and a higher score on the Charlson index were associated with more periods with an eye examination. Male gender, being limited in instrumental activities of daily living at baseline, distance to the nearest ophthalmologist, and low cognitive function were associated with a reduction in frequency of eye examinations.

CONCLUSIONS

Rates of eye examinations for elderly persons with DM or frequently occurring eye diseases, especially for DM, remain far below recommended levels in a nationally representative sample of persons with health insurance coverage. Several factors, including limited physical and cognitive function and greater distance to an ophthalmologist, but not health insurance coverage, account for variation in regular use.