Annals of internal medicine
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To review the clinical use of noninvasive positive pressure ventilation, including its efficacy with acute and chronic forms of respiratory failure, its mechanism of action, and its implementation. ⋯ Noninvasive positive pressure ventilation is effective in the treatment of chronic respiratory failure due to restrictive thoracic diseases. The routine use of such treatment for chronic respiratory failure due to chronic obstructive pulmonary disease and for acute respiratory failure needs to be studied in randomized controlled trials in better-defined patient subsets.
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Data on body weight and weight change collected from nationally representative samples of U. S. adults are reviewed. The body mass index (weight [kg]/height [m2]) has a low correlation with height and is used to compare body weights between persons of differing heights. ⋯ Longitudinal body weight measurements taken 10 years apart show that adults younger than 55 years tend to gain weight, whereas those 55 years and older tend to lose weight. The youngest adults gain the most weight, and the oldest adults lose the most weight. In all age groups, women have substantially greater variation in their 10-year weight change than do men.
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Clinicians and policymakers are recognizing the importance of measuring health-related quality of life (HRQL) to inform patient management and policy decisions. Self- or interviewer-administered questionnaires can be used to measure cross-sectional differences in quality of life between patients at a point in time (discriminative instruments) or longitudinal changes in HRQL within patients during a period of time (evaluative instruments). Both discriminative and evaluative instruments must be valid (really measuring what they are supposed to measure) and have a high ratio of signal to noise (reliability and responsiveness, respectively). ⋯ The approaches are not mutually exclusive. Each approach has its strengths and weaknesses and may be suitable for different circumstances. Investigations in HRQL have led to instruments suitable for detecting minimally important effects in clinical trials, for measuring the health of populations, and for providing information for policy decisions.
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To present an overview of the applicability of heart rate variability measurements in medicine. ⋯ Heart rate variability analysis is easily applicable in adult medicine, but physiologic influences such as age must be considered. The most important application is the surveillance of postinfarction and diabetic patients to prevent sudden cardiac death. With heart rate variability analysis, individual therapy adjustments to achieve the most favorable sympathetic-parasympathetic balance might be possible in the future.
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Medical technology assessment seeks to improve the care of individual patients (the conventional unit of clinical practice) through evaluation studies conducted in groups of patients (the conventional unit of clinical investigation). This distinction between individuals and groups has practical relevance to the design, analysis, and clinical applicability of technology assessment studies. We define several biased perspectives about technology assessment that derive from the distinction between individuals and groups: a misguided emphasis on efficacy versus effectiveness, on statistical significance versus clinical importance, and on objective versus subjective outcomes. In each case, we contrast these alternative perspectives and speculate on their implications for health care policy.