Arseniy P. Yashkin

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 individuals 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 studys 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.

How the effects of aging and stresses of life are integrated in mortality rates: insights for genetic studies of human health and longevity

Increasing proportions of elderly individuals in developed countries combined with substantial increases in related medical expenditures make the improvement of the health of the elderly a high priority today. If the process of aging by individuals is a major cause of age related health declines then postponing aging could be an efficient strategy for improving the health of the elderly. Implementing this strategy requires a better understanding of genetic and non-genetic connections among aging, health, and longevity. We review progress and problems in research areas whose development may contribute to analyses of such connections. These include genetic studies of human aging and longevity, the heterogeneity of populations with respect to their susceptibility to disease and death, forces that shape age patterns of human mortality, secular trends in mortality decline, and integrative mortality modeling using longitudinal data. The dynamic involvement of genetic factors in (i) morbidity/mortality risks, (ii) responses to stresses of life, (iii) multi-morbidities of many elderly individuals, (iv) trade-offs for diseases, (v) genetic heterogeneity, and (vi) other relevant aging-related health declines, underscores the need for a comprehensive, integrated approach to analyze the genetic connections for all of the above aspects of aging-related changes. The dynamic relationships among aging, health, and longevity traits would be better understood if one linked several research fields within one conceptual framework that allowed for efficient analyses of available longitudinal data using the wealth of available knowledge about aging, health, and longevity already accumulated in the research field.

Relation between BMI and diabetes mellitus and its complications among US older adults.

Objectives This study examined relations between elevated body mass index (BMI) and time to diagnosis with type 2 diabetes mellitus and its complications among older adults in the United States. Methods Data came from the Medicare Current Beneficiary Survey, 1991–2010. A Cox proportional hazard model was used to assess relations between excess BMI at the first Medicare Current Beneficiary Survey interview and time to diabetes mellitus diagnosis, complications, and insulin dependence among Medicare beneficiaries, older than 65 years of age with no prior diabetes mellitus diagnosis, and who were not enrolled in Medicare Advantage (N = 14,657). Results Among individuals diagnosed as having diabetes mellitus, elevated BMIs were associated with a progressively higher risk of complications from diabetes mellitus. For women with a BMI ≥40, the risk of insulin dependence (hazard ratio [HR] 3.57; 95% confidence interval [CI] 2.36–5.39) was twice that for women with 25 ⩽ BMI < 27.5 (HR 1.77; 95% CI 1.33–2.33). A similar pattern was observed in risk of cardiovascular (25 ⩽ BMI < 27.5: HR 1.34; 95% CI 1.15–1.54; BMI ≥40: HR 2.45; 95% CI 1.92–3.11), cerebrovascular (25 ⩽ BMI < 27.5: HR 1.30; 95% CI 1.06–1.57; BMI ≥40: HR 2.00; 95% CI 1.42–2.81), renal (25 ⩽ BMI < 27.5: HR 1.31; 95% CI 1.04–1.63; BMI ≥40: HR 2.23; 95% CI 1.54–3.22), and lower extremity complications (25 ⩽ BMI < 27.5: HR 1.41; 95% CI 1.22–1.61; BMI ≥40: HR 2.95; 95% CI 2.35–3.69). Conclusions Any increase in BMI above normal weight levels is associated with an increased risk of being diagnosed as having complications of diabetes mellitus. For men, the increased risk of these complications occurred at higher BMI levels than in women. Ocular complications occurred at higher BMI levels than other complication types in both men and women.

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.

Causes of the change in the rates of mortality and severe complications of diabetes mellitus: 1992-2012.

Objective:To quantify the causes of the changes in the rates of mortality and select severe complications of diabetes mellitus, type 2 (T2D) among the elderly between 1992 and 2012. Research Design:A retrospective cohort study design based on Medicare 5% administrative claims data from 1992 to 2012 was used. Traditional fee-for-service Medicare beneficiaries, age 65 and older, diagnosed with T2D and living in the United States between 1992 and 2012 were included in the study. Blinder-Oaxaca decomposition was used to quantify the potential causes of the change in the rates of death, congestive heart failure and/or acute myocardial infarction, stroke, amputation of lower extremity and end-stage renal disease between 1992 and 2012. Results:The number of beneficiaries in the analysis sample diagnosed with T2D increased from 152,191 in 1992 to 289,443 in 2012. Over the same time period, rates of mortality decreased by 1.2, congestive heart failure and/or acute myocardial infarction by 2.6, stroke by 1.6, amputation by 0.6 while rates of end-stage renal disease increased by 1.5 percentage points. Improvements in the management of precursor conditions and utilization of recommended healthcare services, not population composition, were the primary causes of the change. Conclusions:With the exception of end-stage renal disease, outcomes among Medicare beneficiaries diagnosed with T2D improved. Analysis suggests that persons diagnosed with T2D are living longer with fewer severe complications. Much of the improvement in outcomes likely reflects more regular contact with health professionals and better management of care.

Pleiotropic Meta-Analyses of Longitudinal Studies Discover Novel Genetic Variants Associated with Age-Related Diseases

Age-related diseases may result from shared biological mechanisms in intrinsic processes of aging. Genetic effects on age-related diseases are often modulated by environmental factors due to their little contribution to fitness or are mediated through certain endophenotypes. Identification of genetic variants with pleiotropic effects on both common complex diseases and endophenotypes may reveal potential conflicting evolutionary pressures and deliver new insights into shared genetic contribution to healthspan and lifespan. Here, we performed pleiotropic meta-analyses of genetic variants using five NIH-funded datasets by integrating univariate summary statistics for age-related diseases and endophenotypes. We investigated three groups of traits: (1) endophenotypes such as blood glucose, blood pressure, lipids, hematocrit, and body mass index, (2) time-to-event outcomes such as the age-at-onset of diabetes mellitus (DM), cancer, cardiovascular diseases (CVDs) and neurodegenerative diseases (NDs), and (3) both combined. In addition to replicating previous findings, we identify seven novel genome-wide significant loci (< 5e-08), out of which five are low-frequency variants. Specifically, from Group 2, we find rs7632505 on 3q21.1 in SEMA5B, rs460976 on 21q22.3 (1 kb from TMPRSS2) and rs12420422 on 11q24.1 predominantly associated with a variety of CVDs, rs4905014 in ITPK1 associated with stroke and heart failure, rs7081476 on 10p12.1 in ANKRD26 associated with multiple diseases including DM, CVDs, and NDs. From Group 3, we find rs8082812 on 18p11.22 and rs1869717 on 4q31.3 associated with both endophenotypes and CVDs. Our follow-up analyses show that rs7632505, rs4905014, and rs8082812 have age-dependent effects on coronary heart disease or stroke. Functional annotation suggests that most of these SNPs are within regulatory regions or DNase clusters and in linkage disequilibrium with expression quantitative trait loci, implying their potential regulatory influence on the expression of nearby genes. Our mediation analyses suggest that the effects of some SNPs are mediated by specific endophenotypes. In conclusion, these findings indicate that loci with pleiotropic effects on age-related disorders tend to be enriched in genes involved in underlying mechanisms potentially related to nervous, cardiovascular and immune system functions, stress resistance, inflammation, ion channels and hematopoiesis, supporting the hypothesis of shared pathological role of infection, and inflammation in chronic age-related diseases.

Pleiotropic Associations of Allelic Variants in a 2q22 Region with Risks of Major Human Diseases and Mortality

Gaining insights into genetic predisposition to age-related diseases and lifespan is a challenging task complicated by the elusive role of evolution in these phenotypes. To gain more insights, we combined methods of genome-wide and candidate-gene studies. Genome-wide scan in the Atherosclerosis Risk in Communities (ARIC) Study (N = 9,573) was used to pre-select promising loci. Candidate-gene methods were used to comprehensively analyze associations of novel uncommon variants in Caucasians (minor allele frequency~2.5%) located in band 2q22.3 with risks of coronary heart disease (CHD), heart failure (HF), stroke, diabetes, cancer, neurodegenerative diseases (ND), and mortality in the ARIC study, the Framingham Heart Study (N = 4,434), and the Health and Retirement Study (N = 9,676). We leveraged the analyses of pleiotropy, age-related heterogeneity, and causal inferences. Meta-analysis of the results from these comprehensive analyses shows that the minor allele increases risks of death by about 50% (p = 4.6×10−9), CHD by 35% (p = 8.9×10−6), HF by 55% (p = 9.7×10−5), stroke by 25% (p = 4.0×10−2), and ND by 100% (p = 1.3×10−3). This allele also significantly influences each of two diseases, diabetes and cancer, in antagonistic fashion in different populations. Combined significance of the pleiotropic effects was p = 6.6×10−21. Causal mediation analyses show that endophenotypes explained only small fractions of these effects. This locus harbors an evolutionary conserved gene-desert region with non-coding intergenic sequences likely involved in regulation of protein-coding flanking genes ZEB2 and ACVR2A. This region is intensively studied for mutations causing severe developmental/genetic disorders. Our analyses indicate a promising target region for interventions aimed to reduce risks of many major human diseases and mortality.

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.

Pure and Confounded Effects of Causal SNPs on Longevity: Insights for Proper Interpretation of Research Findings in GWAS of Populations with Different Genetic Structures

This paper shows that the effects of causal SNPs on lifespan, estimated through GWAS, may be confounded and the genetic structure of the study population may be responsible for this effect. Simulation experiments show that levels of linkage disequilibrium (LD) and other parameters of the population structure describing connections between two causal SNPs may substantially influence separate estimates of the effect of the causal SNPs on lifespan. This study suggests that differences in LD levels between two causal SNP loci within two study populations may contribute to the failure to replicate previous GWAS findings. The results of this paper also show that successful replication of the results of genetic association studies does not necessarily guarantee proper interpretation of the effect of a causal SNP on lifespan.

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.