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The causal relationship between multiple cardiovascular diseases and glioblastoma: A Mendelian randomization study.

Observational studies suggest an association between glioblastoma (GBM) and cardiovascular diseases (CVDs), but a causal relationship remains unestablished. This study aimed to investigate the causal link between multiple CVDs and GBM risk. The inverse variance weighted method indicated that all 18 CVDs had significant causal associations with GBM (P&#x2005;<&#x2005;.05). Genetically predicted CVDs were uniformly associated with a lower risk of GBM (odds ratio&#x2005;<&#x2005;1), identifying them as potential protective factors. Sensitivity analyses confirmed the absence of significant heterogeneity or horizontal pleiotropy, and the MR-Steiger test validated the correct causal direction. This Mendelian randomization (MR) study provides evidence that a range of CVDs are causally associated with a decreased risk of developing GBM. These findings suggest shared biological pathways and offer new insights for understanding GBM etiology. We conducted a 2-sample MR analysis using publicly available genome-wide association study data. GBM was the outcome, and 18 cardiovascular-related traits (including coronary artery disease, myocardial infarction, and venous thromboembolism) were exposures. Instrumental variables were single-nucleotide polymorphisms significantly associated with exposures (P&#x2005;<&#x2005;5&#x2005;&#xd7;&#x2005;10-8). The primary analysis used the inverse variance weighted method, supplemented with MR-Egger, weighted median, and weighted mode methods. Sensitivity analyses, including Cochran Q test, MR-Egger intercept test, leave-one-out analysis, and MR-Steiger directionality test, were performed to ensure robustness.

Causality↗

Migraine is not a risk factor for glaucoma: Evidence from a bidirectional Mendelian randomization study.

Numerous compelling observational studies have indicated that migraine is a risk factor for the development of glaucoma. Nevertheless, some studies have observed entirely opposite results. The objective of our research is to evaluate the potential relationship between migraine and glaucoma by employing a bidirectional Mendelian Randomization (MR) approach. This method enables us to rigorously assess the causal links between these 2 conditions, thereby addressing the discrepancies in existing literature. Independent genetic variants associated with glaucoma and migraine at the genome-wide significance level were selected as instrumental variables. All summary data were obtained from the genome-wide association study database. The primary method employed in the bidirectional MR analysis was the inverse variance weighted method, while sensitivity analyses utilized the leave-one-out method, MR-Egger method, and MR-Pleiotropy RESidual Sum and Outlier&#x200c; method. When migraine and its subtypes (specifically migraine with aura and migraine without aura) were evaluated as exposure factors, we found no evidence of a causal relationship with glaucoma and its subtypes (namely angle-closure glaucoma and open-angle glaucoma). Subsequently, in the reverse MR analysis, when glaucoma and its subtypes (angle-closure glaucoma and open-angle glaucoma) were assessed as exposure factors, there was no substantial evidence to support a causal relationship with migraine or its subtypes (migraine with aura and migraine without aura). Furthermore, sensitivity analyses also reinforced the robustness of our bidirectional MR findings. Our bidirectional MR analysis mitigates the biases associated with traditional observational studies, highlighting that there is no direct causal relationship between migraine and the risk of glaucoma.

Humans↗

Plasma lipid species, immune cell traits, and gastric cancer risk: A Mendelian randomization study.

Plasma lipid composition has been linked to multiple cancers, yet its causal contribution to gastric cancer and the potential intermediary role of immune cells remain unclear. We aimed to clarify these relationships and identify specific lipid and immune cell traits that either protect against or promote gastric cancer. We performed a 2-sample, 2-step Mendelian randomization analysis using summary statistics from large genome-wide association studies of gastric cancer (1423 cases, 3,14,193 controls), plasma lipidomics (179 molecular species), and 731 immune cell phenotypes. Independent, genome-wide significant single-nucleotide variants served as instrumental variables. First, we estimated the causal effects of each plasma lipid on gastric cancer. Then, we explored the potential intermediary role of lipid-associated immune cell traits using a 2-step Mendelian randomization framework. Two lipids - phosphatidylethanolamine (18:0 0:0) and phosphatidylcholine (O-18:0 16:1) - were causally associated with a lower risk of gastric cancer. Three immune cell traits (CD8br and CD8dim %leukocyte, IgD on IgD+ CD38- and CD3 on CD28- CD8br) similarly showed protective effects. In contrast, phosphatidylcholine (O-16:1 18:2), triacylglycerol (49:1), triacylglycerol (56:3), and triacylglycerol (56:4) increased gastric cancer risk, as did immune traits such as TD DN (CD4-CD8-)AC, CD19 on memory B cell, CD28 on CD39+ activated Treg, CD45 on CD4+, CD127 on CD28+DN(CD4-CD8-) and CCR2 on CD14+CD16+ monocyte. Exploratory mediation analyses found no statistically significant evidence that immune cell traits mediated the effects of plasma lipids on gastric cancer risk. Specific phosphatidylethanolamines and phosphatidylcholines confer protection against gastric cancer, whereas several triacylglycerols increase risk. However, exploratory mediation analyses provided no statistically significant evidence that immune cell traits mediated these associations.

Humans↗

Exploring the Relationship Between Serological Metabolites and Oral Cancer: A Mendelian Randomization Study.

BACKGROUND: Oral cancer is a prevalent malignant tumor, comprising &#x223c;5% to 6% of all tumors. The 5-year survival rate for this condition is &#x223c;50%. However, the early symptoms of oral cancer are often inconspicuous and easily overlooked, leading to frequent misdiagnosis or missed diagnosis. Although some previous studies have investigated the correlation between oral cancer and serum metabolites, the exact relationship remains unclear. Consequently, it is of utmost importance to develop effective early diagnosis methods and explore the pathogenesis of oral cancer to enhance patients' survival rates and quality of life. METHODS: This Mendelian randomization (MR) study utilized the Genome-Wide Association Study (GWAS) catalog to obtain instrumental variables (IVs) that link 486 serum metabolites with oral cancer. The study then conducted a causal analysis, using serological metabolites as exposure factors and oral cancer as the outcome. The samples used in the study were exclusively from the European population. The main method used for the univariate MR analysis was the inverse variance weighting method. After excluding confounding factors, MR analysis was performed again. Sensitivity analyses were subsequently conducted to enhance the robustness of the MR results. Furthermore, metabolic pathway analysis was carried out on serum metabolites associated with oral cancer, aiming to identify and explore potential metabolic pathways. RESULTS: After MR analysis, 8 serum metabolites were screened out that are highly correlated with the causal relationship with oral cancer, including androsterone sulfate (OR=2.11, 95% CI: 1.37-3.27, P =0.0007), X-12100--hydroxytryptophan (OR=0.12, 95% CI: 0.02-0.73, P =0.022), gamma-glutamylphenylalanine (OR=7.57, 95% CI: 1.17-48.85, P =0.033), 7-methylxanthine (OR=0.22, 95% CI: 0.05-0.90, P =0.035), urate (OR=12.03, 95% CI: 1.16-124.32, P =0.037), palmate (16:0) (OR=11.01, 95% CI: 1.11-109.13, P =0.040), creatinine (OR=0.03, 95% CI: 0.00-0.90, P =0.047), guanosine (OR=2.66, 95% CI: 1.00-7.04, P =0.049), and the absence of heterogeneity and horizontal pleiotropy in this study indicates that the MR results obtained are quite reliable. CONCLUSION: Androsterone sulfate, gamma-glutamylphenylalanine, urate, palmitate (16:0), creatinine, and guanosine have been identified as risk factors for oral cancer. In contrast, X-12100--hydroxytryptophan and 7-methylxanthine may have a protective effect against oral cancer. The findings of this study have significant implications for early oral cancer diagnosis and offer valuable insights into the disease's pathogenesis.

Mendelian Randomization Analysis↗

CAUSAL ASSOCIATION BETWEEN SEPSIS AND FIBROBLAST GROWTH FACTORS AS WELL AS THEIR RECEPTORS LEVELS: A TWO-SAMPLE MENDELIAN RANDOMIZATION STUDY.

Objective: The potential association between sepsis risk and circulating levels of fibroblast growth factors (FGFs) and their receptors (FGFRs) has been a focus of research; however, the causal relationship between them remains to be elucidated. We hypothesize a causal association between genetically predicted FGFs, FGFRs, and sepsis risk, and we conduct a Mendelian randomization (MR) study to validate this hypothesis. Methods: We utilized a two-sample MR design to assess the effect of genetic variants associated with various FGFs (FGF1, FGF2, FGF7, FGF16, FGF19, FGF21, FGF23, FGF5) and FGFRs (FGFR1, FGFR2, FGFR3, &#x3b1;-Klotho) on sepsis risk, using genome-wide association study summary statistics. Our MR analyses employed the inverse-variance weighted (IVW) method, along with weighted median, weighted mode, and MR-Egger regression, supplemented by sensitivity analyses to ensure robustness. Results: The MR analysis identified an unequal number of instrumental variables ranging from 2 to 17 for FGFs and FGFRs when sepsis was the outcome. No significant correlation was found between genetically determined FGF levels and sepsis risk by IVW analysis (all P > 0.05). Correspondingly, similar nonsignificant associations were observed for FGFRs (all P > 0.05). Other MR methods corroborated the IVW findings. Sensitivity analyses, including Cochran's Q test, MR-Egger, and MR pleiotropy residual sum and outlier, indicated no significant heterogeneity or pleiotropy in the relationships, with the exception of a nonsignificant correlation between FGFR1 and sepsis that persisted after the exclusion of an outlier (odds ratio, 0.84; P = 0.34). Conclusion: The analysis found no significant causal associations between FGFs, their receptors, and sepsis risk, indicating a need for further research on their complex interactions.

Humans↗

Hyperthyroidism Is Genetically Associated With Reduced Risk of Parkinson's Disease: A Mendelian Randomization Analysis.

Parkinson's disease (PD) is a progressive neurodegenerative disorder whose aetiology involves an intricate interplay of genetic, immune, metabolic and environmental factors. Endocrine dysfunction-particularly disturbances of thyroid hormone signalling-has been proposed as a contributor to neurodegeneration, but conventional observational studies have produced inconsistent results, and prior Mendelian randomization (MR) work has largely focused on continuous thyroid biomarkers rather than clinically defined hyperthyroid disease states. To clarify this relationship, we performed a two-sample bidirectional and multivariable MR (MVMR) analysis using large-scale genome-wide association study (GWAS) summary statistics from the FinnGen and IEU Open GWAS databases (European ancestry). Single-nucleotide polymorphisms (SNPs) reaching genome-wide significance (p&#x2009;<&#x2009;5&#x2009;&#xd7;&#x2009;10-8) for Graves' disease and thyrotoxicosis with diffuse goitre served as instrumental variables. The inverse-variance weighted (IVW) method was the primary analysis, complemented by MR-Egger, weighted median, weighted mode and simple mode estimators, and MVMR adjusted for smoking, alcohol consumption, and body mass index (BMI). In forward analyses, genetically proxied Graves' disease (OR&#x2009;=&#x2009;0.942, 95% CI 0.901-0.985, p&#x2009;=&#x2009;0.008) and thyrotoxicosis with diffuse goitre (OR&#x2009;=&#x2009;0.929, 95% CI 0.879-0.982, p&#x2009;=&#x2009;0.009) were associated with a lower risk of PD, whereas reverse analyses showed no significant effect of genetic liability to PD on either thyroid trait. The inverse associations remained stable across MVMR models, and sensitivity analyses (Cochran's Q, MR-Egger intercept, MR-PRESSO, leave-one-out) showed no evidence of heterogeneity or horizontal pleiotropy. Collectively, these findings provide genetic evidence consistent with a protective relationship between hyperthyroid disease states and PD, independent of major lifestyle confounders. By focusing on clinically defined hyperthyroid entities rather than continuous thyroid indices, our study complements prior MR work and highlights the thyroid-brain axis-encompassing thyroid hormone signalling and autoimmune-mediated immune modulation-as a biologically plausible and potentially modifiable contributor to PD risk that warrants further mechanistic and translational investigation.

Humans↗

Cell Type-Resolved Causal Inference and Spatial Transcriptomic Integration Reveal Immune-Specific Genetic Drivers of Autoimmune and Malignant Thyroid Disease.

BACKGROUND: Thyroid diseases, including autoimmune thyroid disease (AITD) and thyroid cancer, are characterized by immune dysregulation, yet the cell type-specific genetic mechanisms underlying these conditions remain poorly understood. Most genome-wide association studies (GWAS) have relied on bulk tissue expression quantitative trait loci (eQTL), which cannot resolve the heterogeneity of immune cell populations. METHODS: We performed two-sample Mendelian randomization (MR) analyses using single-cell cis-eQTLs from 14 immune cell subtypes (OneK1K cohort) as instrumental variables against GWAS summary statistics for four thyroid outcomes: autoimmune hyperthyroidism, autoimmune hypothyroidism, thyroid cancer and autoimmune thyroiditis. Causal associations were validated through Bayesian colocalization, phenome-wide association analysis (PheWAS) and multi-layered transcriptomic validation encompassing spatial transcriptomics of AITD tissue (GSE248205), bulk RNA-seq of thyroid cancer (GSE3678) and single-cell RNA-seq of thyroid tumours (GSE250521). gsMap spatial LD score regression was applied to map disease heritability onto spatial tissue architecture. RESULTS: We identified six Bonferroni-significant causal gene-cell type pairs for autoimmune hyperthyroidism, including protective effects of ABHD16A in na&#xef;ve/immature B cells (OR&#xa0;=&#xa0;0.440), HIST1H3H in CD8 NC T cells (OR&#xa0;=&#xa0;0.324), HMGN4 in NK recruiting cells (OR&#xa0;=&#xa0;0.556) and ZKSCAN4 in CD8 S100B T cells (OR&#xa0;=&#xa0;0.427), with five pairs showing strong colocalization (PP.H4 &#x2265; 86%). Three pairs reached significance for autoimmune hypothyroidism, including a risk association of HLA-F in CD4 NC T cells (OR&#xa0;=&#xa0;1.139). For autoimmune thyroiditis, FAM134B/RETREG1 showed consistent suggestive protective associations across both CD4 and CD8 NC T cells (PP.H4 &#x2265; 90% for both), suggesting a possible involvement of ER phagy regulation in thyroiditis susceptibility. Thyroid cancer showed a suggestive association with HLA-G in classical monocytes (OR&#xa0;=&#xa0;1.899, PP.H4&#xa0;=&#xa0;53%). Spatial transcriptomic validation demonstrated progressive immune infiltration from control tissue to Graves' disease to Hashimoto's thyroiditis (7.7%-15.7%, 46.1%-54.1%, respectively) and strong spatial correlation between target gene expression and corresponding cell type enrichment (e.g., plasma cell-HLA-DQB1: r&#xa0;=&#xa0;0.491, p < 10-300). HLA-G was independently validated in thyroid cancer bulk (log2fc&#xa0;=&#xa0;0.542, p&#xa0;=&#xa0;9.51&#xa0;&#xd7;&#xa0;10-3, AUC&#xa0;=&#xa0;0.857) and single-cell datasets. PheWAS revealed no significant associations detected for the core candidates. gsMap identified significant enrichment of autoimmune hypothyroidism heritability in gastrointestinal tract, adrenal gland and adipose tissue (all Bonferroni p < 0.002). CONCLUSIONS: This study establishes a multi-scale analytical framework integrating cell type-resolved genetic inference with spatial tissue validation, revealing distinct immunogenetic architectures underlying autoimmune versus malignant thyroid disease. Protective genetic programs in autoimmune hyperthyroidism converge on chromatin remodelling (HIST1H3H, HMGN4, ZKSCAN4) and lipid metabolism (ABHD16A) across lymphocyte subsets, whereas thyroid cancer risk involves immune escape mediated by HLA-G in myeloid cells. The ER-phagy receptor RETREG1 represents a candidate pathway warranting further investigation in autoimmune thyroiditis. These findings provide genetically supported, cell type-specific therapeutic targets and demonstrate a generalizable strategy for dissecting the immune-mediated mechanisms of complex thyroid diseases.

Mendelian randomization↗

The impact of managed care on substance abuse treatment services.

OBJECTIVE: To examine the impact of managed care on the number and types of services offered by substance abuse treatment (SAT) facilities. Both the number and types of services offered are important factors to analyze, as research shows that a broad range of services increases treatment effectiveness. DATA SOURCES: The 2000 National Survey of Substance Abuse Treatment Services (NSSATS), which is designed to collect data on service offerings and other characteristics of SAT facilities in the United States. These data are merged with data from the 2002 Area Resource File (ARF), a county-specific database containing information on population and managed care activity. We use data on 10,513 facilities, virtually a census of all SAT facilities. STUDY DESIGN: We estimate the impact of managed care (MC) on the number and types of services offered by SAT facilities using instrumental variables (IV) techniques that account for possible endogeneity between facilities' involvement in MC and service offerings. Due to limitations of the NSSATS data, MC and specific services are modeled as binary variables. PRINCIPAL FINDINGS: We find that managed care causes SAT facilities to offer, on average, approximately two fewer services. This effect is concentrated primarily in medical testing services (i.e., tests for TB, HIV/AIDs, and STDs). We also find that MC increases the likelihood of offering substance abuse assessment and relapse prevention groups, but decreases the likelihood of offering outcome follow-up. CONCLUSION: Our findings raise policy concerns that managed care may reduce treatment effectiveness by limiting the range of services offered to meet patient needs. Further, reduced onsite medical testing may contribute to the spread of infectious diseases that pose important public health concerns.

AIDS Serodiagnosis↗

Availability of safety net providers and access to care of uninsured persons.

OBJECTIVE: To understand how proximity to safety net clinics and hospitals affects a variety of measures of access to care and service use by uninsured persons. DATA SOURCES: The 1998-1999 Community Tracking Study household survey, administered primarily by telephone survey to households in 60 randomly selected communities, linked to data on community health centers, other free clinics, and safety net hospitals. STUDY DESIGN: Instrumental variable estimation of multivariate regression models of several measures of access to care (having a usual source of care, unmet or delayed medical care needs, ambulatory service use, and overnight hospital stays) against endogenous measures of distances to the nearest community health center and safety net hospital, controlling for characteristics of uninsured persons and other area characteristics that are related to access to care. The models are estimated with data from a nationally representative sample of uninsured people. PRINCIPAL FINDINGS: Shorter distances to the nearest safety net providers increase access to care for uninsured persons. Failure to account for the endogeneity of distance to safety net providers on access to care generally leads to finding little or no safety net effects on access. CONCLUSIONS: Closer proximity to the safety net increases access to care for uninsured persons. However, the improvements in access to care are relatively small compared with similar measures of access to care for insured persons. Modest expansion of the safety net is unlikely to provide a full substitute for insurance coverage expansions.

Adult↗

Effective HIV treatment and the employment of HIV(+) adults.

OBJECTIVE: To examine whether highly active antiretroviral therapy (HAART) helps HIV-infected patients return to work, remain employed, and maintain hours of work. DATA SOURCE: Longitudinal data from a national probability sample of HIV+ patients older than 18 years old who made at least one visit in the contiguous United States in early 1996. STUDY DESIGN: We consider the effect of HAART on three employment outcomes: (1) returning to work within six months of treatment, conditional on not working pretreatment; (2) remaining employed within six months of treatment, conditional on working pretreatment; (3) hours of work conditional on working at the second follow-up survey. We use a bivariate probit model to jointly model employment and treatment with HAART for the first two outcomes and the two-stage least squares method for hours of work. State policies regarding prescription drug coverage are used as instrumental variables for HAART to account for a key source of potential bias-the more severely ill tend to have the most difficulty working, but are also the most likely to be on HAART. PRINCIPAL FINDINGS: Our results indicate that HAART increases the probability of remaining employed by HIV patients and hours of work for those working within six months of treatment. In the case of remaining employed, the employment effect (an increase from 58 percent to 94 percent in the probability of remaining employed) is statistically significant and the related incremental income is sizable compared to the incremental costs of HAART. Sensitivity analyses demonstrate that the results are robust to different specifications for insurance coverage. CONCLUSIONS: Patients who are working are more likely to remain employed because of treatment with HAART. HAART prescribed to patients in less advanced stages of the infection may lead to the greatest gain in employment.

Adult↗

How well does Medicaid work in improving access to care?

OBJECTIVE: To provide an assessment of how well the Medicaid program is working at improving access to and use of health care for low-income mothers. DATA SOURCE/STUDY SETTING: The 1997 and 1999 National Survey of America's Families, with state and county information drawn from the Area Resource File and other sources. STUDY DESIGN: Estimate the effects of Medicaid on access and use relative to private coverage and being uninsured, using instrumental variables methods to control for selection into insurance status. DATA COLLECTION/EXTRACTION METHOD: This study combines data from 1997 and 1999 for mothers in families with incomes below 200 percent of the federal poverty level. PRINCIPAL FINDINGS: We find that Medicaid beneficiaries' access and use are significantly better than those obtained by the uninsured. Analysis that controls for insurance selection shows that the benefits of having Medicaid coverage versus being uninsured are substantially larger than what is estimated when selection is not accounted for. Our results also indicate that Medicaid beneficiaries' access and use are comparable to that of the low-income privately insured. Once insurance selection is controlled for, access and use under Medicaid is not significantly different from access and use under private insurance. Without controls for insurance selection, access and use for Medicaid beneficiaries is found to be significantly worse than for the low-income privately insured. CONCLUSIONS: Our results show that the Medicaid program improved access to care relative to uninsurance for low-income mothers, achieving access and use levels comparable to those of the privately insured. Our results also indicate that prior research, which generally has not controlled for selection into insurance coverage, has likely understated the gains of Medicaid relative to uninsurance and overstated the gains of private coverage relative to Medicaid.

Adult↗

Increasing health insurance costs and the decline in insurance coverage.

OBJECTIVE: To determine the impact of rising health insurance premiums on coverage rates. DATA SOURCES & STUDY SETTING: Our analysis is based on two cohorts of nonelderly Americans residing in 64 large metropolitan statistical areas (MSAs) surveyed in the Current Population Survey in 1989-1991 and 1998-2000. Measures of premiums are based on data from the Health Insurance Association of America and the Kaiser Family Foundation/Health Research and Educational Trust Survey of Employer-Sponsored Health Benefits. STUDY DESIGN: Probit regression and instrumental variable techniques are used to estimate the association between rising local health insurance costs and the falling propensity for individuals to have any health insurance coverage, controlling for a rich array of economic, demographic, and policy covariates. PRINCIPAL FINDINGS: More than half of the decline in coverage rates experienced over the 1990s is attributable to the increase in health insurance premiums (2.0 percentage points of the 3.1 percentage point decline). Medicaid expansions led to a 1 percentage point increase in coverage. Changes in economic and demographic factors had little net effect. The number of people uninsured could increase by 1.9-6.3 million in the decade ending 2010 if real, per capita medical costs increase at a rate of 1-3 percentage points, holding all else constant. CONCLUSIONS: Initiatives aimed at reducing the number of uninsured must confront the growing pressure on coverage rates generated by rising costs.

Adult↗

Does the impact of managed care on substance abuse treatment services vary by provider profit status?

OBJECTIVE: To extend our previous research by determining whether, and how, the impact of managed care (MC) on substance abuse treatment (SAT) services differs by facility ownership. DATA SOURCES: The 2000 National Survey of Substance Abuse Treatment Services, which is designed to collect data on service offerings and other characteristics of SAT facilities in the U.S. These data are merged with data from the 2002 Area Resource File, a county-specific database containing information on population and MC activity. We use data on 10,513 facilities, virtually a census of all SAT facilities. STUDY DESIGN: For each facility ownership type (for-profit [FP], not-for-profit [NFP], public), we estimate the impact of MC on the number and types of SAT services offered. We use instrumental variables techniques that account for possible endogeneity between facilities' involvement in MC and service offerings. PRINCIPAL FINDINGS: We find that the impact of MC on SAT service offerings differs in magnitude and direction by facility ownership. On average, MC causes FPs to offer approximately four additional services, causes publics to offer approximately four fewer services, and has no impact on the number of services offered by NFPs. The differential impact of MC on FPs and publics appears to be concentrated in therapy/counseling, medical testing, and transitional services. CONCLUSION: Our findings raise policy concerns that MC may reduce the quality of care provided by public SAT facilities by limiting the range of services offered. On the other hand, we find that FP clinics increase their range of services. One explanation is that MC results in standardization of service offerings across facilities of different ownership type. Further research is needed to better understand both the specific mechanisms of MC on SAT and the net impact on society.

Health Facilities, Proprietary↗

Health insurance and health at age 65: implications for medical care spending on new Medicare beneficiaries.

OBJECTIVES: To investigate the consequences of endogeneity bias on the estimated effect of having health insurance on health at age 63 or 64, just before most people qualify for Medicare, and to simulate the implications for total and public insurance (Medicare and Medicaid) spending on newly enrolled beneficiaries in their first years of Medicare coverage. DATA: The longitudinal Health and Retirement Survey of people who were 55-61 years old in 1992, followed through biannual surveys to age 63-64 or until 2000 (whichever came first), and those who were 66-70 years olds from the Medicare Current Beneficiary Surveys, 1992-1998. STUDY DESIGN: Instrumental variable (IV) estimation of a simultaneous equation model of insurance choice and health at age 63-64 as a function of baseline health and sociodemographic characteristics in 1992 and endogenous insurance coverage over the observation period. FINDINGS: Continuous insurance coverage is associated with significantly fewer deaths prior to age 65 and, among those who survive, a significant upward shift in the distribution of health states from fair and poor health with disabilities to good to excellent health. Treating insurance coverage as endogenous increases the magnitude of the estimated effect of having insurance on improved health prior to age 65. The medical spending simulations suggest that if the near-elderly had continuous insurance coverage, average annual medical spending per capita for new Medicare beneficiaries in their first few years of coverage would be slightly lower because of the improvement in health status. In addition, total Medicare and Medicaid spending for new beneficiaries over their first few years of coverage would be about the same or slightly lower, even though more people survive to age 65. CONCLUSIONS: Extending insurance coverage to all Americans between the ages of 55 and 64 would improve health (increase survival and shift people from good-fair-poor health to excellent-very good health) at age 65, and possibly reduce total short-term spending by Medicare and Medicaid for newly eligible Medicare beneficiaries, even though more people would enter the program because of increased survival.

Aged↗

Functional outcomes of posthospital care for stroke and hip fracture patients under medicare.

BACKGROUND: Medicare's introduction of the Prospective Payment System for hospitals has led to tremendous growth in ways of providing posthospital care. Despite substantial differences in costs per episode of care, the type of posthospital care that produces the best results for specific types of patients is not clear. This study analyzed the outcomes of different types of posthospital care for a cohort of older Medicare patients (who had diagnoses associated with the use of a range of posthospital care modalities) for up to a year after hospital discharge. METHODS: Medicare patients hospitalized with strokes and hip fractures were enrolled consecutively just before discharge from 52 hospitals in three cities in 1988-1989. These diagnosis-related groups were chosen because patients were discharged to all three major types of Medicare-supported posthospital care. Patients were interviewed in-person before discharge and again at 6 weeks, 6 months, and 1 year after discharge. The functional outcomes of posthospital care were evaluated by the instrumental variables estimation approach to correct for selection bias caused by nonrandom treatment assignment. The impacts of discharge locations on the functional outcomes were examined by one-way analyses of variance (ANOVA). RESULTS: In general, the more disabled patients went to nursing homes and rehabilitation, but the overlap in distribution was sufficient to conduct the analyses. Stroke patients discharged to nursing homes had the highest mortality rate (P<.01). Stroke patients discharged to home health had the lowest rehospitalization rates (P<.05). Hip fracture discharged to home health care had the highest adjusted rehospitalization rate, whereas those discharged to nursing homes had the lowest adjusted rehospitalization rate (P<.05). For stroke patients, posthospital care in rehabilitation facilities or home health care was associated with significantly better functional improvement compared with stroke patients discharged elsewhere. However, functional outcomes deteriorated by 1 year posthospitalization among stroke patients who received their posthospital care at nursing homes or received no formal posthospital care. For hip fracture patients, all four types of posthospital care were associated with functional improvement, but patients discharged to rehabilitation facilities experienced the most functional improvement. CONCLUSIONS: The choice of posthospital care can influence the course of Medicare patients. Careful attention should be paid to how hospital discharge decisions are made and to the financial incentives for different types of posthospital care provided under the current payment system. The current supply of nursing homes is not well suited to the demands of posthospital care.

Activities of Daily Living↗

Longitudinal analysis of the relationship between regular eye examinations and changes in visual and functional status.

OBJECTIVES: To determine whether regular eye examinations are associated with a greater or lesser rate of loss of ability to read newsprint, onset of blindness or low vision, or onset of limitations in instrumental activities of daily living (IADLs) and activities of daily living (ADLs). DESIGN: A sample of 14,215 Medicare beneficiaries observed between 1994 and 1999 linked to the 1994 and 1999 National Long-Term Care Surveys (NLTCS). Effects of annual examinations were assessed using instrumental variables. SETTING: The Medicare-linked NLTCS is representative of U.S. elderly persons from 1994 to 1999. PARTICIPANTS: Longitudinal observational study of persons aged 65 and older. MEASUREMENTS: Change in self-reported and provider-reported vision and change in functional limitations associated with vision related to the number of years with eye examinations and other factors. RESULTS: Persons with more-regular eye examinations between 1994 and 1998 were less likely to have experienced a decline in vision or in functional status between 1994 and 1999. On average, an additional year with an eye examination was associated with a decrease in the probability of becoming unable to read newsprint of 0.12 (P=.03), a lower probability of onset of low vision or blindness of 0.009 (P=.06), and a decrease in the probability that the number of functional limitations increased of 0.13 (P=.002) for IADLs and 0.05 (P=.003) for ADLs. CONCLUSION: Elderly persons who have regular eye examinations experience less decline in vision and functional status.

Activities of Daily Living↗

Stratified analysis in randomized trials with noncompliance.

This article develops methods for stratified analyses of additive or multiplicative causal effect on binary outcomes in randomized trials with noncompliance. The methods are based on a weighted estimating function for an unbiased estimating function under randomization in each stratum. When known weights are used, the derived estimator is a natural extension of the instrumental variable estimator for stratified analyses, and test-based confidence limits are solutions of a quadratic equation in the causal parameter. Optimal weights that maximize asymptotic efficiency incorporate variability in compliance aspects across strata. An assessment based on asymptotic relative efficiency shows that a substantial enhancement in efficiency can be gained by using optimal weights instead of conventional ones, which do not incorporate the variability in compliance aspects across strata. Application to a field trial for coronary heart disease is provided.

Cholesterol↗

Ultrasonographic evaluation of equine tendons: a quantitative in vitro study of the effects of amplifier gain level, transducer-tilt, and transducer-displacement.

The objective of the in vitro experiments described in this paper was to quantify the effects of some instrumental variables on the quantitative evaluation, by means of first-order gray-level statistics, of ultrasonographic images of equine tendons. The experiments were done on three isolated equine superficial digital flexor tendons that were mounted in a frame and submerged in a waterbath. Sections with either normal tendon tissue, an acute lesion, or a chronic scar, were selected. In these sections, the following experiments were done: 1) a gradual increase of total amplifier gain output subdivided in 12 equal steps; 2) a transducer tilt plus or minus 3 degrees from perpendicular, with steps of 1 degree; and 3) a transducer displacement along, and perpendicular to, the tendon long axis, with 16 steps of 0.25 mm each. Transverse ultrasonographic images were collected, and in the regions of interest (ROI) first-order gray-level statistics were calculated to quantify the effects of each experiment. Some important observations were: 1) the total amplifier gain output has a substantial influence on the ultrasonographic image; for example, in the case of an acute lesion, a low gain setting results in an almost completely black image; whereas, with higher gain settings, a marked "filling in" effect on the lesion can be observed; 2) the relative effects of the tilting of the transducer are substantial in normal tendon tissue (18%) and chronic scar (12%); whereas, in the event of an acute lesion, the effects on the mean gray level are dramatic (40%); and 3) the relative effects of displacement of the transducer are small in normal tendon tissue, but on the other hand, the mean gray-level changes 7% in chronic scar, and even 20% in an acute lesion. In general, slight variations in scanner settings and transducer handling can have considerable effects on the gray levels of the ultrasonographic image. Furthermore, there is a strong indication that this quantitative method, as far as based exclusively on the first-order gray-level statistics, may be not discriminative enough to accurately assess the integrity of the tendon. Therefore, the value of a quantitative evaluation of the first-order gray-level statistics for the assessment of the integrity of the equine tendon is questionable.

Animals↗