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Demographic studies of mortality often emphasize the two ends of the lifespan, focusing on the declining hazard after birth or the increasing risk of death at older ages. We call attention to the intervening phase, when humans are least vulnerable to the force of mortality, and consider its features in both evolutionary and historical perspectives. We define this quiescent phase (Q-phase) formally, estimate its bounds using life tables for Swedish cohorts born between 1800 and 1920, and describe changes in the morphology of the Q-phase. We show that for cohorts aging during Sweden's demographic and epidemiological transitions, the Q-phase became longer and more pronounced, reflecting the retreat of infections and maternal mortality as key causes of death. These changes revealed an underlying hazard trajectory that remains relatively low and constant during the prime ages for reproduction and investment in both personal capital and relationships with others. Our characterization of the Q-phase highlights it as a unique, dynamic, and historically contingent cohort feature, whose increased visibility was made possible by the rapid pace of survival improvements in the nineteenth and twentieth centuries. This visibility may be reduced or sustained under subsequent demographic regimes.

Background: Few studies focus on "preclinical" warning signs associated with mortality. In this article, we investigate associations between all-cause mortality and two clusters of biological risk factors: (i) standard clinical measures related to cardiovascular disease and metabolic function; and (ii) nonclinical measures pertaining to hypothalamic-pituitary-adrenal axis activity, sympathetic nervous system activity, and inflammatory response., Methods: Data come from the 2000 Social Environment and Biomarkers of Aging Study, a national sample of Taiwanese persons aged 54 years or older; 1497 persons were interviewed in their homes, and 1023 participated in a hospital examination. The analysis is based on 927 respondents with complete information. Logistic regression models describe the association between biomarkers and the 3-year probability of dying., Results: Although both groups of biomarkers are significantly associated with mortality, the model with neuroendocrine and immune biomarkers has better explanatory and discriminatory power than the one with clinical measures. The association between these nonclinical measures and mortality remains strong after adjustment for the clinical markers, suggesting that the physiological effects of the nonclinical biomarkers are broader than those captured by the cardiovascular and metabolic system measures included here., Conclusions: Nonclinical markers are likely to provide warning signs of deteriorating health and function beyond what can be learned from conventional markers. Our findings are consistent with those of recent studies that (i) demonstrate the importance of neuroendocrine and immune system markers for survival, and (ii) indicate that standard clinical variables are less predictive of mortality in older than in younger populations.

Objective: To account for variations in death rates in population subgroups of the USA., Methods: Factors associated with age-adjusted death rates in 366 metropolitan and non- metropolitan areas of the United States were examined for 1990-92. The rates ranged from 690 to 1108 per 100 000 population (mean = 885 +/- 78 per 100 000)., Findings: Least squares regression analysis explained 71% of this variance. Factors with the strongest independent positive association were ethnicity (African-American), less than a high school education, high Medicare expenditures, and location in western or southern regions. Factors with the strongest independent negative associations were employment in agriculture and forestry, ethnicity (Hispanic) and per capita income., Conclusion: Additional research at the individual level is needed to determine if these associations are causal, since some of the factors with the strongest associations, such as education, have long latency periods.

Objectives. Studies of late-life disablement typically address the role of advancing age as a factor in developing disability, and in some cases have pointed out the importance of time to death (TTD) in understanding changes in functioning. However, few studies have addressed both factors simultaneously, and none have dealt satisfactorily with the problem of missing data on TTD in panel studies. Methods. We fit latent-class trajectory models of disablement using data from the Health and Retirement Study. Among survivors (~20% of the sample), TTD is unknown, producing a missingdata problem. We use an auxiliary regression equation to impute TTD and employ multiple imputation techniques to obtain final parameter estimates and standard errors. Results. Our best-fitting model has 3 latent classes. In all 3 classes, the probability of having a disability increases with nearness to death; however, in only 2 of the 3 classes is age associated with disability. We find gender, race, and educational differences in class-membership probabilities. Discussion. The model reveals a complex pattern of age- and time-dependent heterogeneity in late-life disablement. The techniques developed here could be applied to other phenomena known to depend on TTD, such as cognitive change, weight loss, and health care spending. [ABSTRACT FROM AUTHOR]

The authors comment on the connection between remaining lifetime and the trajectory of late-life disability. Few critics have argued that using time to death (TTD) as a predictor of disability confuses the direction of causality. They said the author's our approach to imputation of TTD among censored observations is not valid because TTD is not missing at random (MAR).

Background: The effectiveness of implantable cardioverter-defibrillators (ICDs) on reducing mortality has not been well studied in patients with long QT syndrome (LQTS).Objectives: This study aimed to assess the survival benefits of ICDs in the overall LQTS population and in subgroups defined by ICD indications.Methods: This study included 3,035 patients (597 with ICD) from the Rochester LQTS Registry with a QTc ≥470 milliseconds or confirmed LQTS mutation. Using multivariable Cox proportional hazards models, the risk of all-cause mortality, all-cause mortality before age 50 years, and sudden cardiac death (SCD) were estimated as functions of time-dependent ICD therapy. Indication subgroups examined included patients with: 1) nonfatal cardiac arrest; 2) syncope while on beta-blockers; and 3) a QTc ≥500 milliseconds and syncope while off beta-blockers.Results: During the 118,837 person-years of follow-up, 389 patients died (137 before age 50 years, and 116 experienced SCD). In the entire population, patients with ICDs had a lower risk of death (HR: 0.54; 95% CI: 0.34-0.86), death before age 50 years (HR: 0.29; 95% CI: 0.14-0.61), and SCD (HR: 0.22; 95% CI: 0.09-0.55) than patients without ICDs did. Patients with ICDs also had a lower risk of mortality among the 3 indication subgroups (HR: 0.14; 95% CI: 0.06-0.34; HR: 0.27; 95% CI: 0.10-0.72; and HR: 0.42; 95% CI: 0.19-0.96, respectively).Conclusions: ICD therapy was associated with a lower risk of all-cause mortality, all-cause mortality before age 50 years, and SCD in the LQTS population, as wells as with a lower risk of all-cause mortality in indication subgroups. This study provides evidence supporting ICD implantation in patients with high-risk LQTS. [ABSTRACT FROM AUTHOR]

Introduction: Implantable Cardioverter Defibrillators (ICD) are an important treatment option for Long QT syndrome (LQTS) patients at high risk of cardiac arrest. The aim of the study was to assess the effect of ICDs in reducing mortality in the overall LQTS population and in subgroups defined by ICD indications. Methods: This study included 3035 subjects (597 ever had an ICD) from the Rochester-based LQTS Registry with a QTc ≥ 470 ms or a confirmed LQTS mutation. Using multivariable Cox models with follow-up starting from 1 year of age, we assessed the relative risk of overall mortality, mortality censored at 50 years of age, and sudden cardiac death (SCD) associated with time-varying ICD status. The effect of ICD on the risk of mortality by subgroups (prior aborted cardiac arrest [ACA], prior syncope while on beta blockers, and all others without these two indications) was assessed by including interaction terms of the time-varying ICD status and the time-varying indication groups. Results: There were 389 deaths including 116 SCDs during a follow-up of 118,837 person-years. Those with an ICD had a 46% lower risk of death than those without an ICD (HR=0.54, 95%CI: 0.33 - 0.86), adjusted for other risk factors. The ICD HRs for mortality censored at 50 years of age and SCD were 0.25 (95%CI: 0.11 - 0.56) and 0.17 (95%CI: 0.06 - 0.50), respectively. Among those with prior ACA, ICD patients had an 82% lower risk of death than non-ICD patients (HR=0.18, 95%CI: 0.07 - 0.46). Among those with prior syncope on beta-blockers, ICD patients had a 57% (approaching statistical significance) lower risk of death (HR=0.43, 95%CI: 0.18 - 1.08) than non-ICD patients. Among other patients with no prior ACA nor syncope on beta-blockers, there was no evidence of a mortality benefit of ICD (Figure 1). Conclusions: ICD was associated with reduced risk of mortality and SCD in LQTS patients. The results by time-varying indication groups support the current recommendation regarding ICD implantation in LQTS patients. [ABSTRACT FROM AUTHOR]