Dmitry Tumin

Obesity and Mortality Risk: New Findings From Body Mass Index Trajectories

Little research has addressed the heterogeneity and mortality risk in body mass index (BMI) trajectories among older populations. Applying latent class trajectory models to 9,538 adults aged 51 to 77 years from the US Health and Retirement Study (1992-2008), we defined 6 latent BMI trajectories: normal weight downward, normal weight upward, overweight stable, overweight obesity, class I obese upward, and class II/III obese upward. Using survival analysis, we found that people in the overweight stable trajectory had the highest survival rate, followed by those in the overweight obesity, normal weight upward, class I obese upward, normal weight downward, and class II/III obese upward trajectories. The results were robust after controlling for baseline demographic and socioeconomic characteristics, smoking status, limitations in activities of daily living, a wide range of chronic illnesses, and self-rated health. Further analysis suggested that BMI trajectories were more predictive of mortality risk than was static BMI status. Using attributable risk analysis, we found that approximately 7.2% of deaths after 51 years of age among the 1931-1941 birth cohort were due to class I and class II/III obese upward trajectories. This suggests that trajectories of increasing obesity past 51 years of age pose a substantive threat to future gains in life expectancy.

Center Volume and Extracorporeal Membrane Oxygenation Support at Lung Transplantation in the Lung Allocation Score Era

RATIONALE Outcomes related to extracorporeal membrane oxygenation (ECMO) used to bridge patients to lung transplantation in the context of center differences in transplant expertise have not been investigated. OBJECTIVES To determine the effects of ECMO at time of transplant on survival in adult patients who underwent transplant surgery in historically low- and high-volume centers. METHODS The United Network for Organ Sharing database was used to classify centers according to transplant volume between May 2005 and May 2010 as low-volume centers (bottom 50% of centers), medium-volume centers (next 25%), or high-volume centers (top 25%). Influences of ECMO on post-transplant survival were estimated among adults receiving lung transplants between June 2010 and June 2015 based on historic center volume in the preceding 5 years. MEASUREMENTS AND MAIN RESULTS Sixty-five centers were classified according to lung transplant volume in 2005-2010, with 8,228 adults (279 on ECMO) who underwent transplants at these centers between June 2010 and June 2015 included in the survival analysis. In multivariable Cox analysis stratified by center, we found that, in historically low-volume centers, ECMO was associated with increased post-transplant mortality hazard (hazard ratio, 1.968; 95% confidence interval, 1.083-3.577; P = 0.026). In contrast, in historically high-volume centers, ECMO had no adverse influence on post-transplant survival (hazard ratio, 0.853; 95% confidence interval, 0.596-1.222; P = 0.386). CONCLUSIONS An adverse effect of ECMO at the time of lung transplant was evident in low-volume centers but absent in centers with experience of performing more than 170 lung transplants in the first 5 years of the lung allocation score era.

Whom Do Immigrants Marry? Emerging Patterns of Intermarriage and Integration in the United States

We document patterns of intermarriage between immigrants and natives during a period of unprecedented growth in the size and diversity of America’s foreign-born population. Roughly one in six U.S. marriages today involve immigrants and a large share includes U.S.-born partners. Ethno-racial background clearly shapes trajectories of immigrant social integration. White immigrants are far more likely than other groups to marry U.S.-born natives, mostly other whites. Black immigrants are much less likely to marry black natives or out-marry with other groups. Intermarriage is also linked with other well-known proxies of social integration—educational attainment, length of time in the country, and naturalization status. Classifying America’s largest immigrant groups (e.g., Chinese and Mexican) into broad panethnic groups (e.g., Asians and Hispanics) hides substantial diversity in the processes of marital assimilation and social integration across national origin groups.

Reported Nonadherence to Immunosuppressive Medication in Young Adults After Heart Transplantation: A Retrospective Analysis of a National Registry.

BackgroundYoung adult heart transplantation (HTx) recipients experience high mortality risk attributed to increased nonadherence to immunosuppressive medication in this age window. This study sought to test whether a high-risk age window in HTx recipients persisted in the absence of reported nonadherence. MethodsHeart transplantation recipients aged 2 to 40 years, transplanted between October 1999 and January 2007, were identified in the United Network for Organ Sharing database. Multivariable survival analysis was used to estimate influences of age at transplantation and attained posttransplant age on mortality hazard among patients stratified by center report of nonadherence to immunosuppression that compromised recovery. ResultsThree thousand eighty-one HTx recipients were included, with univariate analysis demonstrating peak hazards of mortality and reported nonadherence among 567 patients transplanted between ages 17 and 24 years. Multivariable analysis adjusting for reported nonadherence demonstrated lower mortality among patients transplanted at younger (hazards ratio, 0.813; 95% confidence interval, 0.663-0.997; P = 0.047) or older (hazards ratio, 0.835; 95% confidence interval, 0.701-0.994; P = 0.042) ages. Peak mortality hazard at ages 17 to 24 years was confirmed in the subgroup of patients with no nonadherence reported during follow-up. This result was replicated using attained age after HTx as the time metric, with younger and older ages predicting improved survival in the absence of reported nonadherence. ConclusionsLate adolescence and young adulthood coincide with greater mortality hazard and greater chances of nonadherence to immunosuppressive medication after HTx, but the elevation of mortality hazard in this age range persists in the absence of reported nonadherence. Other causes of the high-risk age window for post-HTx mortality should be demonstrated to identify opportunities for intervention.

Health Insurance Trajectories and Long-Term Survival After Heart Transplantation

Background—Health insurance status at heart transplantation influences recipient survival, but implications of change in insurance for long-term outcomes are unclear. Methods and Results—Adults aged 18 to 64 receiving first-time orthotopic heart transplants between July 2006 and December 2013 were identified in the United Network for Organ Sharing registry. Patients surviving >1 year were categorized according to trajectory of insurance status (private compared with public) at wait listing, transplantation, and 1-year follow-up. The most common insurance trajectories were continuous private coverage (44%), continuous public coverage (27%), and transition from private to public coverage (11%). Among patients who survived to 1 year (n=9088), continuous public insurance (hazard ratio =1.36; 95% confidence interval 1.19, 1.56; P<0.001) and transition from private to public insurance (hazard ratio =1.25; 95% confidence interval 1.04, 1.50; P=0.017) were associated with increased mortality hazard relative to continuous private insurance. Supplementary analyses of 11 247 patients included all durations of post-transplant survival and examined post-transplant private-to-public and public-to-private transitions as time-varying covariates. In these analyses, transition from private to public insurance was associated with increased mortality hazard (hazard ratio =1.25; 95% confidence interval 1.07, 1.47; P=0.005), whereas transition from public to private insurance was associated with lower mortality hazard (hazard ratio =0.78; 95% confidence interval 0.62, 0.97; P=0.024). Conclusions—Transition from private to public insurance after heart transplantation is associated with worse long-term outcomes, compounding disparities in post-transplant survival attributed to insurance status at transplantation. By contrast, post-transplant gain of private insurance among patients receiving publicly funded heart transplants was associated with improved outcomes.

Lung transplant center volume ameliorates adverse influence of prolonged ischemic time on mortality

The influence of prolonged ischemic time on outcomes after lung transplant is controversial, but no research has investigated ischemic time in the context of center volume. We used data from the United Network for Organ Sharing to estimate the influence of ischemic time on patient survival conditional on center volume in the post–lung allocation score era (2005–2015). The analytic sample included 14 877 adult lung transplant recipients, of whom 12 447 were included in multivariable survival analysis. Patient survival was improved in high‐volume centers compared with low‐volume centers (log‐rank test p = 0.001), although mean ischemic times were longer at high‐volume centers (5.16 ± 1.70 h vs. 4.83 ± 1.63 h, p < 0.001). Multivariable Cox proportional hazards regression stratified by transplant center found an adverse influence of longer ischemic time at low‐volume centers but not at high‐volume centers. At centers performing 50 transplants in the period 2005–2015, for example, 8 versus 6 h of ischemia were associated with an 18.9% (95% confidence interval 6.5–32.7%; p < 0.001) greater mortality hazard, whereas at centers performing 350 transplants in this period, no differences in survival by ischemic time were predicted. Despite longer mean ischemic time at high‐volume transplant centers, these centers had favorable patient outcomes and no adverse survival implications of prolonged ischemia.

High local unemployment rates limit work after lung transplantation

BACKGROUND Most lung transplant (LTx) recipients recover sufficient functional status to resume working, yet unemployment is common after LTx. Weak local labor markets may limit employment opportunities for LTx recipients. METHODS United Network for Organ Sharing data on first-time LTx recipients 18-60 years old who underwent transplant between 2010 and 2014 were linked to American Community Survey data on unemployment rates at the ZIP Code level. Multivariable competing-risks regression modeled the influence of dichotomous (≥8%) and continuous local unemployment rates on employment after LTx, accounting for the competing risk of mortality. For comparison, analyses were duplicated in a cohort of heart transplant (HTx) recipients who underwent transplant during the same period. RESULTS The analysis included 3,897 LTx and 5,577 HTx recipients. Work after LTx was reported by 300 (16.3%) residents of low-unemployment areas and 244 (11.9%) residents of high-unemployment areas (p < 0.001). Multivariable analysis of 3,626 LTx recipients with complete covariate data found that high local unemployment rates limited employment after LTx (sub-hazard ratio = 0.605; 95% confidence interval = 0.477, 0.768; p < 0.001), conditional on not working before transplant. Employment after HTx was higher compared with employment after LTx, and not associated with local unemployment rates in multivariable analyses. CONCLUSIONS LTx recipients of working age exhibit exceptionally low employment rates. High local unemployment rates exacerbate low work participation after LTx, and may discourage job search in this population.

No survival benefit to gaining private health insurance coverage for post-lung transplant care in adults with cystic fibrosis.

The use of public insurance is associated with diminished survival in patients with cystic fibrosis (CF) following lung transplantation. No data exist on benefits of gaining private health insurance for post‐transplant care among such patients previously using public insurance. The United Network for Organ Sharing database was used to identify first‐time lung transplant recipients participating in Medicare or Medicaid, diagnosed with CF, and transplanted between 2005 and 2015. Survival outcomes were compared between recipients gaining private insurance after transplantation and those maintaining public coverage throughout follow‐up. Since implementation of the lung allocation score, 575 adults with CF received lung transplantation funded by Medicare or Medicaid and contributed data on insurance status post‐transplant. There were 128 (22%) patients who gained private insurance. Multivariable analysis of time‐varying insurance status found no survival benefit of gaining private insurance (HR = 0.822; 95% CI = 0.525, 1.286; p = 0.390). Further analysis demonstrated that resuming public insurance coverage was detrimental, relative to gaining and keeping private insurance (HR = 2.315; 95% CI = 1.020, 5.258; p = 0.045). Survival disadvantages of lung transplant recipients with CF who have public health insurance were not ameliorated by a switch to private coverage for post‐transplant care.

The effect of the affordable care act dependent coverage provision on patients with cystic fibrosis

The Patient Protection and Affordable Care Act (ACA), enacted in 2010, expanded private insurance coverage of young adults through the dependent coverage provision. This policys implications for patients with cystic fibrosis (CF) are unknown.

Pulmonary Artery Pressure and Benefit of Lung Transplantation in Adult Cystic Fibrosis Patients

BACKGROUND The effect of lung transplantation (LTx) in patients afflicted with cystic fibrosis (CF) and pulmonary hypertension (PH) at placement on the waiting list is not well studied. METHODS To predict the relationship between initial mean pulmonary artery pressure (MPAP) and hazard ratio (HR) of death after listing associated with LTx in adult patients with CF, the United Network for Organ Sharing database was queried for the years 2005 to 2013. Survival was assessed from waiting list entry until death on the waiting list, death after LTx, or censoring. A multivariate Cox model was performed to estimate the HR of LTx conditional on MPAP at listing. RESULTS Of 1,841 patients with CF, 10% (177) died on the waiting list, 18% (325) were censored without undergoing LTx, and 73% (1,339) underwent transplantation, 361 of whom died after transplantation. A multivariate Cox model of survival since list entry including 1,336 patients found a protective but statistically insignificant benefit of LTx for patients whose MPAP at listing was 25 mm Hg (HR, 0.879; 95% confidence interval [CI], 0.657-1.177; p = 0.388), yet LTx was predicted to be more protective at higher initial MPAP levels, as indicated by the significant interaction term between LTx and MPAP (HR, 0.953; 95% CI, 0.928-0.978; p < 0.001). The predicted LTx HR and 95% CI were protective (HR < 1) at p < 0.05 for patients with MPAP greater than or equal to 30 mm Hg at listing. CONCLUSIONS Survival benefit of LTx in CF was increasingly protective at higher MPAP levels, with a severity level of PH established above which a survival advantage of LTx was found.