The synergy of low lung function and low body mass index predicting all-cause mortality among older Japanese-American men

Physical stature decline and the health status of the elderly population in England

Few research papers in economics have examined the extent, causes or consequences of physical stature decline in aging populations. Using repeated observations on objectively measured data from the English Longitudinal Study of Aging (ELSA), we document that reduction in height is an important phenomenon among respondents aged 50 and over. On average, physical stature decline occurs at an annual rate of between 0.08% and 0.10% for males, and 0.12% and 0.14% for females-which approximately translates into a 2-4 cm reduction in height over the life course. Since height is commonly used as a measure of long-run health, our results demonstrate that failing to take age-related height loss into account substantially overstates the health advantage of older birth cohorts relative to their younger counterparts. We also show that there is an absence of consistent predictors of physical stature decline at the individual level. However, we demonstrate how deteriorating health and reductions in height occur simultaneously. We document that declines in muscle mass and bone density are likely to be the mechanism through which these effects are operating. If this physical stature decline is determined by deteriorating health in adulthood, the coefficient on measured height when used as an input in a typical empirical health production function will be affected by reverse causality. While our analysis details the inherent difficulties associated with measuring height in older populations, we do not find that significant bias arises in typical empirical health production functions from the use of height which has not been adjusted for physical stature decline. Therefore, our results validate the use of height among the population aged over 50.

Comparing the Relationship Between Stature and Later Life Health in Six Low and Middle Income Countries

This paper examines the relationship between stature and later life health in 6 emerging economies, each of which are expected to experience significant increases in the mean age of their populations over the coming decades. Using data from the WHO Study on Global Ageing and Adult Health (SAGE) and pilot data from the Longitudinal Ageing Study in India (LASI), I show that various measures of health are associated with height, a commonly used proxy for childhood environment. In the pooled sample, an additional 10cm increase in height is associated with between a 2 and 3 percentage point increase in the probability of being in very good or good self-reported health, a 3 percentage point increase in the probability of reporting no difficulties with activities of daily living or instrumental activities of daily living, and between a fifth and a quarter of a standard deviation increase in grip strength and lung function. Adopting a methodology previously used in the research on inequality, I also summarise the height-grip strength gradient for each country using the concentration index, and provide a decomposition analysis.

Overweight and obesity may lead to under-diagnosis of airflow limitation: findings from the Copenhagen City Heart Study

BACKGROUND

The prevalence of obesity has increased during the last decades and varies from 10-20% in most European countries to approximately 32% in the United States. However, data on how obesity affects the presence of airflow limitation (AFL) defined as a reduced ratio between forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) are scarce.

METHODS

Data was derived from the third examination of the Copenhagen City Heart Study from 1991 until 1994 (n = 10,135). We examine the impact of different adiposity markers (weight, body mass index (BMI), waist circumference, waist-hip ratio, and abdominal height) on AFL. AFL was defined in four ways: FEV1/FVC ratio < 0.70, FEV1/FVC ratio < lower limit of normal (LLN), FEV1/FVC ratio <0.70 including at least one respiratory symptom, and FEV1/FVC ratio < LLN and FEV1% of predicted < LLN.

RESULTS

All adiposity markers were positively and significantly associated with FEV1/FVC independent of age, sex, height, smoking status, and cumulative tobacco consumption. Among all adiposity markers, BMI was the strongest predictor of FEV1/FVC. FEV1/FVC increased with 0.04 in men and 0.03 in women, as BMI increased with 10 units (kg · m-2). Consequently, diagnosis of AFL was significantly less likely in subjects with BMI ≥ 25 kg · m-2 with odds ratios 0.63 or less compared to subjects with BMI between 18.5-24.9 kg · m-2 when AFL was defined as FEV1/FVC < 0.70.

CONCLUSION

High BMI reduces the probability of AFL. Ultimately, this may result in under-diagnosis and under-treatment of COPD among individuals with overweight and obesity.

Correlation of oxidative status with BMI and lung function in COPD

OBJECTIVES

The imbalance in oxidative status together with nutrition depletion and low body weight play a vital role in the pathogenesis and severity of chronic obstructive pulmonary disease (COPD). The study was undertaken to ascertain if a relationship existed between oxidative status and BMI in COPD. In addition, association of oxidative status and BMI with lung function of the disease was also examined.

MATERIALS AND METHODS

In 202 COPD patients and 136 healthy controls plasma lipid peroxidation (LPO), reduced glutathione (GSH), glutathione peroxidase (GPx), catalase (CAT) activities, BMI and FEV(1)% predicted were looked for interactions.

RESULTS

The patients had increased LPO (p=0.006) and decreased antioxidants (GSH, p=0.005; GPx, p=0.035 and CAT, p=0.008, respectively). Of note are the correlations of oxidative stress markers with BMI and FEV(1)% predicted in the patients. LPO inversely and GSH, GPx, and CAT positively correlated with both BMI (p=0.007, p<0.001, p=0.045 and p=0.009, respectively), and FEV(1)% of predicted (LPO, p=0.001; GSH, p<0.001; GPx, p=0.043 and CAT, p<0.001) in the patients. Further, a positive correlation existed between BMI and FEV(1)% predicted (p=0.016) in COPD.

CONCLUSION

The intimate relationship of oxidative status with BMI and lung function, and the direct correlation between BMI and FEV(1) may potentiate severity of the disease.

Elevated body mass index and mortality risk in the elderly

The purpose of this report was to perform a systematic review and meta-analysis of the studies examining the impact of an elevated body mass index (BMI) on mortality risk in elderly (> or =65 years) men and women. A variance-based method of meta-analysis was used to summarize the relationships from available studies. The summary relative risk of all-cause mortality from the 26 analyses that included a risk estimate for a BMI within the overweight range was 1.00 (95% confidence intervals, 0.97-1.03). The summary relative risk of all-cause mortality for the 28 analyses that included a risk estimate for a BMI within the obese range was 1.10 (1.06-1.13). These calculations indicate that a BMI in the overweight range is not associated with a significantly increased risk of mortality in the elderly, while a BMI in the moderately obese range is only associated with a modest increase in mortality risk.

Frailty, morbidity and survival

Frailty, as a reflection of decreased physical reserve rather than disability, is assessed by various functional tests rather than by specific disease burden. We investigated association of measures of frailty to disease outcomes and survival in a population-based study of Midwestern adults. The markers of frailty we evaluated were: time to walk a measured course (gait-time), handgrip strength, peak respiratory flow rate, ability to stand from a sitting position without using arms, and best corrected visual acuity. A history of cardiovascular disease, cancer, and hypertension were obtained. Data were collected at the third examination (1998--2000) of the Beaver Dam Eye Study cohort (n=2962). Follow-up for mortality occurred up to 412 years after the 1998--2000 examinations. Markers of frailty were significantly associated with age. Values in the highest quartile (slowest) of gait-time, lowest quartile of peak expiratory flow rate, lowest quartile of handgrip strength, inability to stand from sitting in one try (those not in a wheelchair), and visual impairment were combined in an index to denote a general description of frailty. The range of the index was 0 (no frailty) to 5 (maximum frailty). Greater frailty was significantly associated with cardiovascular disease and hypertension. Frailty was associated with poorer survival over an interval of 412 years after adjusting for age, sex, hypertension, diabetes, and cardiovascular disease. Greater frailty was associated with greater likelihood of concurrent medical conditions and with decreased survival.

A cohort study found good respiratory, sensory and motor functions decreased mortality risk in older people

BACKGROUND AND OBJECTIVE

The main aims of this study were to evaluate the separate and joint effects of respiratory, sensory, and psychomotor function, muscle strength, and mobility in predicting mortality in older men and women, and to find a way to control multicollinearity in a multivariate Cox regression model.

METHODS

Mortality was followed for 10 years (1990-2000) in an entire cohort of 75-year-old residents of the city of Jyvaskyla, Finland (born in 1914; N=388). Cox regression models and principal component estimation were employed to study the association between the covariates and mortality.

RESULTS

The study indicated that, after adjustment for fatal diseases and cognitive capacity, vital capacity, tapping rate, muscle strength, and walking speed predict mortality in elderly men and women to a similar extent. The hazard ratio for mortality for those in the lowest tertile of the principal component representing all the significant physiological functions was from three to four times higher than for those in the highest tertile.

CONCLUSION

Our results suggest that a poor level in any of the measured functions has a similar impact on the risk for mortality, which is further increased by combining the different results. No single, dominant predictor of mortality emerged.

Body mass index and the risk of COPD

BACKGROUND

Previous studies have documented the prognostic value of low body weight in patients with COPD and also in general populations. However, it is not clear whether low body weight is a risk factor for COPD or a consequence of established disease.

STUDY OBJECTIVE

To determine whether asymptomatic subjects with low initial body mass were at a greater risk of having COPD develop during subsequent follow-up.

DESIGN AND SUBJECTS

Observational retrospective study of 458 male and 192 female participants (age range, 40 to 73 years) in the Baltimore Longitudinal Study of Aging. At baseline, the participants did not have COPD. After mean follow-up periods of 10.2 years for the men and 6.4 years for the women, 40 men and 7 women received a diagnosis of COPD.

METHODS

Cox proportional-hazards regression models were used to assess the relationship between COPD diagnosis and baseline body mass index (BMI) in men.

RESULTS

The risk of COPD developing in men varied inversely with baseline BMI, even after adjusting for other risk factors, including cigarette smoking, age, FEV(1) percent predicted, abdominal obesity, and educational status. In men, the relative risk of COPD developing for the lowest BMI tertile relative to the highest tertile was 2.76 (95% confidence interval, 1.15 to 6.59). The small number of women who had COPD did not allow us to draw conclusions regarding BMI as a risk factor for COPD.

CONCLUSION

After controlling for confounding variables, men with low BMI are at increased risk for getting COPD.

Predictors of loss of lung function in the elderly: the Cardiovascular Health Study

Pulmonary function, as measured by spirometry (FEV1 or FVC), is an important independent predictor of morbidity and mortality in elderly persons. In this study we examined the predictors of longitudinal decline in lung function for participants of the Cardiovascular Health Study (CHS). The CHS was started in 1990 as a population-based observational study of cardiovascular disease in elderly persons. Spirometry testing was conducted at baseline, 4 and 7 yr later. The data were analyzed using a random effects model (REM) including an AR(1) error structure. There were 5,242 subjects (57.6% female, mean age 73 yr, 87.5% white and 12.5% African-American) with eligible FEV1 measures representing 89% of the baseline cohort. The REM results showed that African-Americans had significantly lower spirometry levels than whites but that their rate of decline with age was significantly less. Subjects reporting congestive heart failure (CHF), high systolic blood pressure (> 160 mm Hg), or taking beta-blockers had significantly lower spirometry levels; however, the effects of high blood pressure and taking beta-blockers diminished with increasing age. Chronic bronchitis, pneumonia, emphysema, and asthma were associated with reduced spirometry levels. The most notable finding of these analyses was that current smoking (especially for men) was associated with more rapid rates of decline in FVC and FEV1. African-Americans (especially women) had slower rates of decline in FEV1 than did whites. Although participants with current asthma had a mean 0.5 L lower FEV1 at their baseline examination, they did not subsequently experience more rapid declines in FEV1.