COPD
-
The Minimal Clinically Important Difference has become a key feature for both the validation of clinical tools and for the assessment of clinical studies. Several methods have been developed to establish what a Minimal Clinically Important Difference is. The primary purpose of the Minimal Clinically Important Difference, however, is to provide a measure of relevance for a statistically applied measure. ⋯ Conversely, parameters that are of great interest to selected individuals, that could be discerned by them with great subtly are likely to be poorly generalizable. Without doubt, defining a Minimal Clinically Important Difference will remain a key goal in the validation and application of tools for clinical investigations. The limits of the concept, particularly as it relates to issues of importance to patients, however, needs to be recognized.
-
Dyspnea is a primary symptom of chronic lung disease and an important outcome measure for clinical trials. Several standardized measures have been developed to evaluate this important symptom and are being used increasingly in clinical trials. ⋯ The analysis is based on a retrospective review of published trials evaluating the response to a pulmonary rehabilitation or exercise intervention that is known to produce modest, but clinically meaningful changes for such patients. Using a distribution-based approach based primarily on effect size, the recommended MCID for these measures are: 5-units for the SOBQ, 1-unit for the Borg scale, and approximately 10 to 20 units for the VAS.
-
Limitation of physical activity occupies a central role in the symptom complex of patients with chronic obstructive pulmonary disease (COPD), and improvement in exercise capacity is a key outcome of response to COPD therapy. Maximum exercise capacity testing facilitates assessment of physiologic mechanisms of exercise and allows quantitation of the degree of limitation. This manuscript utilizes published data from the National Emphysema Treatment Trial to investigate the minimal clinically important difference (MCID) in maximum exercise capacity in patients with severe emphysema. ⋯ In subjects randomized to medical therapy, the mean (+/-SD) 24-month change in maximum exercise capacity following medical therapy was -9.2 +/- 1.2 Watts, whereas among those randomized to lung volume reduction surgery, mean 24-month change in maximum exercise capacity was 1.7 +/- 17.7 Watts, with a mean difference between the groups of 10.9 Watts. The observed difference in maximum exercise capacity after 24 months between subjects randomized to medical versus surgical therapy conforms to both opinion- and distribution-based estimates of MCID. Further investigation is needed to develop and validate estimates of MCID for maximum exercise capacity and other key clinical outcomes in COPD.
-
Review Biography Historical Article
What we owe to alpha(1)-antitrypsin and to Carl-Bertil Laurell.
The archetypal status of alpha(1)-antitrypsin in biology and medicine grew from the finding, thirty years ago, by Carl-Bertil Laurell, of the association of its deficiency with emphysema. In biology, alpha(1)-antitrypsin now provides the model for both the structure and the remarkable mechanism of the serpin protease inhibitors that control the key proteolytic pathways of the body. In medicine, the plasma deficiency of alpha(1)-antitrypsin has drawn attention to protease-antiprotease imbalance as a contributory cause of chronic obstructive pulmonary disease. ⋯ The extensive development of such diverse fields of studies, each based on alpha(1)-antitrypsin, is a measure of the encouragement Laurell gave to younger colleagues in the field. It also reflects the great advantage of linked contributions from clinical as well as basic sciences. Time after time, scientific controversies and deadlocks have been solved by landmark clinical cases, which have revealed unexpected findings and insights, within and beyond the fields of study.
-
Randomized Controlled Trial Comparative Study
Comparison of oral and depot intra-muscular steroids in assessing steroid-responsiveness in COPD.
Non-compliance or euphoria may limit the usefulness of prednisolone tablets in assessing steroid-responsiveness in chronic obstructive pulmonary disease (COPD). Depot intra-muscular methyl-prednisolone (imMP), producing a plateau steroid effect over two weeks, may be more reliable. Following two weeks of placebo, twenty-seven COPD patients (mean FEV 1 43% predicted) participated in a two-week randomised, double-blind, placebo-controlled, parallel-design trial taking either 120 mg imMP with placebo tablets or placebo injection with prednisolone 30 mg daily. ⋯ By contrast, there were small mean improvements in lung function on oral prednisolone (mean FEV 1, FVC and IC increased by 100, 320 and 150 ml, respectively). Only the improvement in FVC was significantly greater after prednisolone compared with imMP. Single depot intra-muscular injections of steroids have no advantage over oral daily prednisolone in testing steroid-responsiveness in COPD patients.