Flawed interpretative strategies for lung function tests harm patients.
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Biomedical subjects
Publications and source records attributed to P Enright.
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Half of the elderly persons with asthma have not been diagnosed, yet their quality of life is substantially lower than others their age. 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 then 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. When spirometry shows airway obstruction post-bronchodilator, a normal diffusing capacity (DLCO) test will rule out COPD in current and former smokers. A normal chest X-ray and B-type natriuretic peptide (BNP) will rule out congestive heart failure (CHF) in those with dyspnea.
STUDY OBJECTIVE: Diffusing capacity of the lung for carbon monoxide (DLCO) is frequently assessed as part of a thorough pulmonary function assessment in patients with pulmonary or cardiopulmonary diseases. However, little information regarding the longitudinal trends of DLCO is available. In this study, we examined the temporal trends in DLCO to determine the effects of smoking and changes in smoking habits. DESIGN: A longitudinal study was recently conducted in the Po River Delta area of northern Italy, in which DLCO measurements were taken approximately 8 years apart in the same subjects; this offered the unique opportunity to assess the temporal changes in DLCO. The longitudinal DLCO data were analyzed independently in two age groups (20 to 40 years, and > or = 40 years) using a repeated-measures analysis. RESULTS: Included were 928 subjects > 20 years old who had DLCO assessments both at baseline and follow-up. Male subjects had higher mean levels of DLCO than female subjects in the older age group (> or = 40 years). Continuous smokers had significantly lower DLCO levels than "never-smokers," but their changes in DLCO during follow-up were the same. This suggests that the lung damage due to smoking had occurred prior to DLCO testing. We also found that the annual decline in DLCO accelerated with age in adults > or = 40 years old. CONCLUSIONS: We conclude that in adults > or = 40 years of age from the general population, DLCO accelerates downwards regardless of gender, smoking, and initial FEV(1) level.
OBJECTIVES: To evaluate study failure and sensor loss in unattended home polysomnography and their relationship to age, gender, obesity, and severity of sleep-disordered breathing (SDB). DESIGN: A cross-sectional analysis of data gathered prospectively for the Sleep Heart Health Study (SHHS). SETTING: Unattended polysomnography was performed in participants' homes by the staff of the sites that are involved in SHHS. PARTICIPANTS: 6,802 individuals who met the inclusion criteria (age >40 years, no history of treatment of sleep apnea, no tracheostomy, no current home oxygen therapy) for SHHS. RESULTS: A total of 6802 participants had 7151 studies performed. 6161 of 6802 initial studies (90.6%) were acceptable. Obesity was associated with a decreased likelihood of a successful initial study. After one or more attempts, 6440 participants (94.7%) had studies that were judged as acceptable. The mean duration of scorable signals for specific channels ranged from 5.7 to 6.8 hours. The magnitudes of the effects of age, gender, BMI, and RDI on specific signal durations were not clinically significant. CONCLUSION: Unattended home PSG as performed for SHHS was usually successful. Participant characteristics had very weak associations with duration of scorable signal. This study suggests that unattended home PSG, when performed with proper protocols and quality controls, has reasonable success rates and signal quality for the evaluation of SDB in clinical and research settings.
INTRODUCTION: As part of the baseline examination in the Cardiovascular Health Study, sleep disturbance symptoms including snoring and daytime sleepiness, were assessed as potential risk factors or precipitants of cardiovascular disease (CVD). Because of the association of sleep disturbance with poorer health and the possible associations of sleep apnea with CVD, we hypothesized that those with poorer sleep or daytime sleepiness may be at increased risk of mortality or incident CVD. SETTING: Participants (n = 5888) were recruited in 1989, with an additional minority cohort recruited in 1993, in four US communities for a cohort study designed to evaluate risk factors for cardiovascular disease. METHODS: An interview-administered questionnaire regarding health and sleep habits with ongoing ascertainment of total mortality and cardiovascular disease morbidity and mortality, including total CVD morbidity and mortality, incident myocardial infarction, and congestive heart failure. RESULTS: Daytime sleepiness was the only sleep symptom that was significantly associated with mortality in both men and women. The unadjusted hazard ratio was 2.12 (1.66, 2.72) in women and 1.40 (1.12, 1.73) in men. Men who reported difficulty falling asleep also had an increased mortality rate (HR = 1.43 (1.14, 1.80)) which was not seen in women. The risks were attenuated with adjustment for age but remained significant for daytime sleepiness in women (HR = 1.82 (1.42, 2.34)) and for difficulty falling asleep in men. (HR = 1.29 (1.03, 1.63)). Frequent awakenings, early morning awakening, and snoring were not associated with a significantly increased risk of mortality in these older men and women. Crude event rates were evaluated for total incident cardiovascular morbidity and mortality, incident myocardial infarction, and incident congestive heart failure (CHF). Incident CVD rates were higher in both men and women with daytime sleepiness. The aged adjusted HR was 1.35 (95% CI = 1.03, 1.76) in men and was 1.66 (95% CI = 1.28, 2.16) in women. Incident CVD was not higher in those with any other sleep disturbance including snoring. The risk of CVD events associated with daytime sleepiness was attenuated but remained significant in women after adjustment for age. Incident myocardial infarction (MI) rates were also higher in women with daytime sleepiness but were not significantly higher in men. Incident CHF rates were increased in both men and women with daytime sleepiness. In men, the age adjusted HR was 1.49 (95% CI, 1.12- 1.98) and in women, was 2.21 (95% CI, 1.64-2.98). Women reporting both daytime sleepiness and frequent awakening had a hazard ratio of 2.34 (95% CI, 1.66-3.29) for incident CHF compared with those with daytime sleepiness but without frequent awakening. This interaction was not found in men. CONCLUSIONS: In this study, daytime sleepiness was the only sleep disturbance symptom that was associated with mortality, incident CVD morbidity and mortality, MI, and CHF. These findings were stronger in women than men, i.e., the associations persisted for mortality, CVD, and CHF in women after adjustment for age and other factors. Thus, a report of daytime sleepiness identifies older adults at increased risk for total and cardiovascular mortality, and is an independent risk factor in women.
BACKGROUND: It is unknown how much age-related changes in muscle performance represent normal aging versus the effects of chronic disease and life style. We examined the correlates of four performance measures-gait speed, timed chair stands (TCS), grip strength, and maximal inspiratory pressure (MIP)-using baseline data from the Cardiovascular Health Study (CHS), a population-based study of risk factors for heart disease and stroke in persons > or = age 65. METHODS: We analyzed data from the 5,201 CHS participants. Variables were arranged into nine categories: Personal Characteristics, Anthropometry, Physical Condition, Reported Functional Status, Subjective Health, Psychological Factors, Symptoms, Cognitive Status, Habits and Lifestyle, and Prevalent Disease. Independent correlates were identified using stepwise linear regression. RESULTS: The regression models explained 17.7-25.4% of the observed variability. Although age significantly correlated with each measure, it explained little of the variability (< or = 5.7%). Anthropometric features plus physical condition explained 14.0-17.4% of the variability for grip strength and MIP, but 2.8-12.9% of the variability for gait speed and the log of TCS. Subjective health and psychological factors explained 1.8-9.4% of the variability in gait speed and the log of TCS, but < or = 1.2% of the variability in grip strength and MIP. Variables for prevalent disease explained < or = 1.3% of the variability in each measure. CONCLUSIONS: After age 64, age explained little of the variability in muscle performance in a large sample of mostly functionally intact, community-dwelling older persons. Complex measures such as gait speed were more associated with subjective factors than were direct measures of strength. Prevalent disease contributed surprisingly little to muscle performance.
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Several studies have demonstrated that smokers who are able to break the habit generally experience reductions in respiratory symptoms and improvement in pulmonary function; however, far less attention has been given to smokers who are unsuccessful in their attempts at quitting. Recent reports have suggested that these subjects (restarters) may have steeper rates of decline in pulmonary function than subjects never attempting to quit smoking. In this study, we compared rates of decline in FEV1 between restarters and subjects who remained current, ex-smokers, or never-smokers throughout the observation period. The results showed that, in both sexes, subjects who attempt to quit the habit and then restart have significantly steeper rates of decline in their FEV1 than subjects who continue smoking uninterrupted. Female restarters also have significantly steeper rates of decline in FEV1 than ex-smokers. These effects were independent of the amount smoked and respiratory diseases.
OBJECTIVE: To define reference hematologic and biochemical lab values in older individuals. DESIGN: Randomly selected, age- and gender-stratified participants. SETTING: Visits by participants to four research clinics. PATIENTS: A total of 5201 participants in the Cardiovascular Health Study, an observational study of older Medicare-eligible individuals living at home. MEASUREMENT: Information about health status, previous illness, and medication use was obtained from participants and/or their MDs. This information was used to define a healthy subset of the population. Blood samples were obtained for Cholesterol, HDL and LDL cholesterol, fasting and 2-hour postload glucose and insulin, fibrinogen, factors VII and VIII, potassium, creatinine, albumin, uric acid, white blood count, hematocrit, hemoglobin, and platelet count. RESULTS: Significant differences were found for age group and/or gender for all mean values. Many tests were significantly different from the generally accepted reference ranges used in clinical laboratories. CONCLUSIONS: In some situations accepted laboratory norms for the general population can not be extrapolated to older adults. There are implications for both research and clinical practice.
Although current recommendations for spirometry require that the largest value of FEV1 and FVC should be taken from the largest values of different maneuvers, the validity of this approach was recently questioned. It has been suggested that selection of the maneuver with the largest peak flow or the maneuver with the largest FVC should be used for measurement of spirometric indices. The present analysis was therefore undertaken to determine which method of selection of spirometric maneuvers would give the least short-term variability in a clinical trial population. We examined the spirometry test sessions from 5,885 individuals with mild to moderate chronic airflow obstruction who were screened at two visits 24.9 +/- 17.1 d apart for entry into a multi-center clinical trial, the Lung Health Study. We compared eight potential selection methods for FEV1 and FVC. Using these different selection methods, the coefficient of variation ranged from 4.1 to 4.9% for FEV1 and from 3.5 to 5.7% for FVC. The average absolute difference between the two test sessions ranged from 110 to 123 ml for FEV1 and from 149 to 200 ml for FVC. Although all of the methods gave good results, the mean of the three highest values and the largest single value from all maneuvers provided the least short-term variability for both FEV1 and FVC. We therefore conclude that there is no reason to change the currently recommended selection methods for FEV1 and FVC.
A century and a half of spirometry testing has seen the most common lung disease change from tuberculosis which reduces lung volumes to emphysema and asthma which reduce flow rates. Spirometers have evolved to highly accurate, relatively inexpensive hand-held instruments. These new spirometers use disposable flow sensors which eliminate the chance of cross-contamination and have microprocessors with programs which monitor and report the quality of the maneuvers as they are performed. Such improvements enable this highly useful diagnostic tool to be used more widely and with greater confidence.
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