Correlates of peak expiratory flow lability in elderly persons

Towards a consensus definition of allostatic load: a multi-cohort, multi-system, multi-biomarker individual participant data (IPD) meta-analysis

BACKGROUND

Allostatic load (AL) is a multi-system composite index for quantifying physiological dysregulation caused by life course stressors. For over 30 years, an extensive body of research has drawn on the AL framework but has been hampered by the lack of a consistent definition.

METHODS

This study analyses data for 67,126 individuals aged 40-111 years participating in 13 different cohort studies and 40 biomarkers across 12 physiological systems: hypothalamic-pituitary-adrenal (HPA) axis, sympathetic-adrenal-medullary (SAM) axis, parasympathetic nervous system functioning, oxidative stress, immunological/inflammatory, cardiovascular, respiratory, lipidemia, anthropometric, glucose metabolism, kidney, and liver. We use individual-participant-data meta-analysis and exploit natural heterogeneity in the number and type of biomarkers that have been used across studies, but a common set of health outcomes (grip strength, walking speed, and self-rated health), to determine the optimal configuration of parameters to define the concept.

RESULTS

There was at least one biomarker within 9/12 physiological systems that was reliably and consistently associated in the hypothesised direction with the three health outcomes in the meta-analysis of these cohorts: dehydroepiandrosterone sulfate (DHEAS), low frequency-heart rate variability (LF-HRV), C-reactive protein (CRP), resting heart rate (RHR), peak expiratory flow (PEF), high density lipoprotein cholesterol (HDL-C), waist-to-height ratio (WtHR), HbA1c, and cystatin C. An index based on five biomarkers (CRP, RHR, HDL-C, WtHR and HbA1c) available in every study was found to predict an independent outcome - mortality - as well or better than more elaborate sets of biomarkers.

DISCUSSION

This study has identified a brief 5-item measure of AL that arguably represents a universal and efficient set of biomarkers for capturing physiological 'wear and tear' and a further biomarker (PEF) that could usefully be included in future data collection.

Asthma Across the Ages: Adults

Asthma is a common disease affecting approximately 300 million people worldwide, across all age ranges. Despite advances in asthma outcomes of the last few decades, there remains room for improvement in asthma management and for patient outcomes, particularly in older patients. The heterogeneity of asthma is now well recognized, and is known to complicate response to treatment and patient behavior and impact health outcomes. Asthma and its heterogeneity change according to age. Asthma affects people differently across the life span. In adults, prevalence is highest among those in middle age; however, mortality is greater in the older age group. In this clinical commentary, we describe how age impacts asthma prevalence and incidence, outcomes, disease expression, and approach to management in adulthood and in older patients.

Asthma Over the Age of 65: All's Well That Ends Well

Asthma in older adults (often classified as those 65 years or older) is relatively common, underdiagnosed, and suboptimally treated. It is an important health problem, as the population of the United States continues to age. Unfortunately, asthma morbidity and mortality rates are highest in this age group. Alterations in the innate and adaptive immune responses occur with aging, and contribute to pathophysiologic differences and subsequent treatment challenges. The symptoms of asthma may differ from those in younger populations, and often include fatigue. There are unique factors that can complicate asthma management among older adults, including comorbidities, menopause, caregiver roles, and depression. Pharmacologic therapies are often not as effective as in younger populations, and may have greater side effects. Spirometry, peak flow measurements, and asthma education are typically underused, and may contribute to delays in diagnosis as well as worse outcomes. There are specific strategies that health care providers can take to improve the care of older adults with asthma.

Asthma in the Elderly

The older population has seen the greatest increase in the prevalence of current asthma in recent years. Asthma may begin at any age and when it occurs at an advanced as opposed to a young age, it is often nonatopic, severe, and unremitting. Unfortunately, geriatric-specific guidelines are not available for the diagnosis and treatment of asthma. However, with objective monitoring, avoidance of asthma triggers, appropriate pharmacotherapy, and patient education, the disease can be managed successfully.

Quantitative relationship between body weight gain in adulthood and incident type 2 diabetes: a meta-analysis

This meta-analysis quantified the risk of type 2 diabetes mellitus (T2DM) preceded by body weight (BW) gain in the general population. Systematic literature searches retrieved 15 eligible studies. The BW gain was divided into early weight-gain, which was defined as BW gain from early adulthood (18-24 years of age) to cohort entry (≥25 years of age), and late weight-gain, which was defined as BW gain from cohort entry. The pooled relative risk (RR; 95% confidence interval [CI]) of T2DM for an increment of BW gain standardized into a 5-kg m(-2) increment in the body mass index (BMI) was 3.07 (2.49-2.79) for early weight-gain and 2.12 (1.74-2.58) for late weight-gain. When limiting analysis to studies that concurrently examined T2DM risk for current BMI (defined in both groups as BMI at cohort entry), a larger magnitude of T2DM risk was revealed for early weight-gain compared with current BMI (RR [95% CI], 3.38 [2.20-5.18] vs. 2.39 [1.58-3.62]), while there was little difference between late weight-gain (RR [95% CI], 2.21 [1.91-2.56]) and current BMI (RR [95% CI], 2.47 [1.97-3.30]). The meta-analysis suggested that BW gain was a quantifiable predictor of T2DM, as well as current obesity in adults. Particularly, BW gain in early rather than middle-to-late adulthood played an important role in developing T2DM.

Asthma and Sleep

Asthma significantly affects quality of sleep. Asthma physiology follows a diurnal pattern with peak flow at its lowest during early morning hours. The type and timing of release of inflammatory mediators also varies during the day and nighttime. Nocturnal symptoms are common in poorly controlled asthma. Hence, these nighttime symptoms play a significant role in the assessment of asthmatic patients as demonstrated in validated asthma control and quality of life questionnaires. Comorbid conditions may include allergic rhinitis, obesity, obstructive sleep apnea, and gastroesophageal reflux, all of which may worsen asthma symptoms, especially during sleep. In addition, exposure to greater loads of allergens in susceptible individuals during sleep is a significant problem and must be addressed to break the cycle of poor asthma control. Thus, asthma education for better symptom control should address these particular issues surrounding sleep.

Asthma in the elderly: Current understanding and future research needs--a report of a National Institute on Aging (NIA) workshop

Asthma in the elderly is underdiagnosed and undertreated, and there is a paucity of knowledge on the subject. The National Institute on Aging convened this workshop to identify what is known and what gaps in knowledge remain and suggest research directions needed to improve the understanding and care of asthma in the elderly. Asthma presenting at an advanced age often has similar clinical and physiologic consequences as seen with younger patients, but comorbid illnesses and the psychosocial effects of aging might affect the diagnosis, clinical presentation, and care of asthma in this population. At least 2 phenotypes exist among elderly patients with asthma; those with longstanding asthma have more severe airflow limitation and less complete reversibility than those with late-onset asthma. Many challenges exist in the recognition and treatment of asthma in the elderly. Furthermore, the pathophysiologic mechanisms of asthma in the elderly are likely to be different from those seen in young asthmatic patients, and these differences might influence the clinical course and outcomes of asthma in this population.

Asthma in older adults

Asthma is underdiagnosed and undertreated in older adults. The classic symptoms, including episodic wheezing, shortness of breath, and chest tightness, are nonspecific in this age group. Older patients may underrate symptoms, and other diseases, such as chronic obstructive pulmonary disease, congestive heart failure, and angina, may have similar presentations. Objective measurements of lung function always should complement the history taking and physical examination. Management of asthma in older adults should include careful monitoring, controlling triggers, optimizing and monitoring pharmacotherapy, and providing appropriate asthma education. Adverse effects to commonly used asthma medications are more common in older adults, and careful monitoring of their use and adverse effects is important.

Aging of the respiratory system: impact on pulmonary function tests and adaptation to exertion

Normal aging of the respiratory system is associated with a decrease in static elastic recoil of the lung, in respiratory muscle performance, and in compliance of the chest wall and respiratory system, resulting in increased work of breathing compared with younger subjects and a diminished respiratory reserve in cases of acute illness, such as heart failure, infection, or airway obstruction. In spite of these changes, the respiratory system remains capable of maintaining adequate gas exchange at rest and during exertion during the entire lifespan, with only a slight decrease in Pa(O2) and no significant change in Pa(CO2).

Comparison of Peak Cough Flows Measured by Pneumotachograph and a Portable Peak Flow Meter

OBJECTIVE

To compare peak cough flows (PCF) obtained with a pneumotachograph (PCFp) with those measured using a portable peak flow meter (PCFm) in a population of healthy subjects and patients with neuromuscular disease.

DESIGN

A total of 30 healthy subjects and 32 medically stable patients with neuromuscular diseases were studied. Using an oronasal mask connected, in a randomized order, to a pneumotachograph and to a portable peak flow meter, PCFp and PCFm were measured as every subject performed maximal cough efforts from total lung capacity.

RESULTS

PCFp measurements were 377.70 +/-179.28 liters/min and PCFm measurements were 377.50 +/- 172.98 liters/min (not significant). The two measurements were correlated (r = 0.95, P < 0.001). The random error obtained was 9.37%. The mean of the differences between the values obtained using both instruments +/- limits of agreement (+2 SD) was 0.20 +/- 109.78 liters/min (not significant). When the agreement was tested over three ranges of flows (< 270 liters/min, 270-480 liters/min, and >480 liters/min), no statistically significant differences were obtained for the population as a whole in any range; however, in the lower flow range, 14 patients had PCFm significantly greater than PCFp (213.93 +/- 55.92 vs. 180.86 +/- 57.22, P = <0.01).

CONCLUSION

PCF measurements made with a portable peak flow meter such as the asmaPLAN+ (Vitalograph, Ennis, Ireland) are reproducible and reasonably accurate when flows are >270 liters/min. However, some caution must be exercised in clinical practice at lower PCF because of the tendency of this portable device to overestimate the lower flows.

Angiotensin-converting enzyme genotype modulates pulmonary function and exercise capacity in treated patients with congestive stable heart failure

BACKGROUND

The gene encoding ACE exhibits an insertion/deletion polymorphism resulting in 3 genotypes (DD, ID, and II), which affects serum and tissue ACE activity as well as other vasoactive substances. Pulmonary function is frequently abnormal in patients with congestive heart failure (CHF), the mechanism of which has not been completely characterized. ACE inhibition has been shown to improve diffusion across the alveolar-capillary membrane and to improve exercise capacity and gas exchange in CHF. The aim of the current study was to determine if ACE genotype is associated with altered pulmonary function and exercise intolerance in patients with treated CHF.

METHODS AND RESULTS

Fifty-seven patients (stratified according to ACE genotype as 17 DD, 28 ID, 12 II) with ischemic and dilated cardiomyopathy, left ventricular ejection fraction (LVEF) <35%, and <10 pack-years of smoking history were studied. All patients were receiving standard therapy for left ventricular systolic dysfunction. Pulmonary function, LVEF, serum ACE, plasma angiotensin II, atrial natriuretic peptide, and brain natriuretic peptide were measured at baseline. Peak VO2 and gas exchange measurements were assessed with graded exercise. Resting LVEF was similar among the genotype groups (25% to 28%), and no differences were observed in diastolic function or pulmonary artery pressures (P>0.05). Mean peak VO2 and forced vital capacity (% Pred) were significantly reduced (P<0.05), whereas mean serum ACE activity and plasma angiotensin II concentration were highest in DD homozygotes. Subjects homozygous for the D-allele also demonstrated higher mean ventilatory equivalents for carbon dioxide (VE/VCO2) during exercise (P<0.05).

CONCLUSIONS

ACE DD genotype is associated with decreased exercise tolerance in CHF, possibly mediated by altered pulmonary function. Pharmacological strategies effecting more complete inhibition of serum and tissue ACE and/or potentiation of bradykinin may improve exercise capacity in patients with CHF and ACE DD genotype.

The diagnosis and management of asthma is much tougher in older patients

Half the elderly individuals with asthma have not been diagnosed, yet their quality of life is substantially impaired. Primary care physicians should, therefore, be encouraged to ask about respiratory symptoms in elderly patients, and then perform office spirometry for those with symptoms. Airway obstruction increases the likelihood of asthma, but the lack of a 'significant' acute bronchodilator response is clinically meaningless. Methacholine challenge testing is safe and useful for detecting asthma in patients with normal baseline spirometry. Only one in five life-long smokers ever develops chronic obstructive pulmonary disease, so elderly smokers should also be evaluated for reversible airways obstruction. A normal diffusing capacity test will rule out emphysema in current and former smokers. Elderly individuals whose asthma has been diagnosed are often receiving sub-optimal treatment, resulting in poor asthma control and a high death rate. Co-morbidities (recognized or not) are the rule in elderly patients, and these conditions, or the drugs taken to treat them, may exacerbate asthma. Conversely, bronchodilators and corticosteroids used to treat asthma often worsen co-morbid conditions, such as osteoporosis, ocular disease, and cardiac arrhythmias. Therefore, extra caution is needed when treating elderly asthmatic patients, and objective monitoring of their response to each new asthma medication is important.