Does the Sensation of Breathlessness Change Over Time in People with Chronic Obstructive Pulmonary Disease? A Systematic Review

A Peer Reviewed Publication of the College of Allied Health & Nursing at Nova Southeastern University Dedicated to allied health professional practice and education http://ijahsp.nova.edu Vol. 7 No. 4 ISSN 1540-580X Does the Sensation of Breathlessness Change Over Time in People with Chronic Obstructive Pulmonary Disease? A Systematic Review Claire McEvoy, B Physiotherapy (Hons)1 Marie Williams, PhD2 1. 2. School of Health Sciences, Division of Health Sciences Associate Professor, School of Health Sciences, Division of Health Sciences University of South Australia Australia CITATION: McEvoy, C., Williams, M. Does the Sensation of Breathlessness Change Over Time in People with Chronic Obstructive Pulmonary Disease? A Systematic Review. The Internet Journal of Allied Health Sciences and Practice. Oct 2009, Volume 7 Number 4. ABSTRACT The aim of this systematic review was to identify and appraise studies which tracked changes in the sensation of breathlessness, as described in terms of intensity, unpleasantness, its effect on impairment levels or quality of life, over two or more years in people with COPD. Four major databases were searched. Twelve studies were included for full analysis. These studies were a mix of observational and experimental in their design, and were found to have high methodological quality. Subjects in the studies were, overall, severely impaired at the start of the two year period, according to level of airflow restriction. Impairment levels did not change dramatically over the two year period (mean decrease of 2%). Thirteen outcome measures were identified within the studies. Modest improvements over the two year period were noted using tools which measure breathlessness intensity and self-reported impairment levels when forms of management were implemented. No clear conclusions could be drawn about changes in quality of life over two years for people with COPD. No studies have reported changes in the quality of the sensation of breathlessness over a minimum two-year period. There is a distinct lack of longitudinal studies tracking changes in the qualitative sensations of breathlessness. INTRODUCTION The last two decades have seen a new wave of research into the sensation of breathlessness. What was previously thought of as a generic sensation commonly experienced by people with respiratory, cardiac, and neuromuscular conditions is now accepted to be as complex and multidimensional as pain. Breathlessness is commonly experienced by people with chronic obstructive pulmonary disease (COPD), and longitudinal studies into the disease frequently use a variety of verified measurement tools to track changes in the intensity or severity of subjects’ breathlessness, their degree of airflow obstruction, and their exercise capacity.1-3 Yet it is only relatively recently that the research and clinical fields have begun to see the benefits of exploring not only the intensity, but also the quality of the sensation of breathlessness. Contemporary neural imaging studies confirm that different neuronal pathways are responsible for the processing of affective (unpleasantness) and sensory (intensity) domains of dyspnoea, and consequently, future studies exploring dyspnoea have been encouraged to use separate visual analogue scales for both unpleasantness and intensity of dyspnoea.4-7 The McGill Pain Questionnaire requires people to select words from a number of domains in order to describe the qualitative sensations of their pain experience. In a similar way, researchers working in the area of breathlessness / dyspnoea have considered the language that people use to describe this sensation as a means of identifying and exploring the qualitative affective domain rather than © The Internet Journal of Allied Health Sciences and Practice, 2009 Does the Sensation of Breathlessness Change Over Time in People with Chronic Obstructive Pulmonary Disease? A Systematic Review 2 simply the intensity of breathlessness. The language used by people to describe the sensation of breathlessness has been shown to reflect underlying pathobiological mechanisms causing the sensation.8 People with COPD can be distinguished from people without the disease through a unique gathering of words and phrases describing the sensation.9 This evidence would suggest that there is a place for tools which also measure the quality of the sensation, and these tools could then be used longitudinally to track changes in the sensation over a period of time. Breathlessness is the most common symptom of COPD. In general, epidemiological studies investigating morbidity/mortality for COPD consider changes over three to five years and give priority to physiological outcomes such as pulmonary function parameters and body mass index as predictors for life expectancy. While epidemiological studies of people with COPD commonly report either the presence or intensity of this symptom, it is unclear to what extent the qualitative domain has been explored and whether changes in this symptom are evident within shorter timeframes. A systematic search of the literature was undertaken to identify studies which reported longitudinal changes in the sensation of breathlessness for people with chronic obstructive pulmonary disease (COPD). The aim was to identify which assessment tools have been used to monitor the sensation of breathlessness (intensity, unpleasantness, or impact upon daily life), and whether the sensation of breathlessness changed over two years in people with COPD. Using the PICO framework, a specific question was formulated for the systematic search. The population (P) of interest was people with COPD. The aim was to assess changes in the sensation of breathlessness over time with natural progression of the disease. The effect of interventions (I) for COPD management was not a specific focus of the review. Studies which included trials of medication or intervention such as pulmonary rehabilitation were included, as these forms of treatment could be considered “usual care” for people with COPD. However, studies in which the sole intervention was surgical (such as lung volume reduction or lung transplant surgery) were excluded, as these interventions were likely to alter the normal course of the disease and subsequent changes in breathlessness. No comparison (C) group was sought. The outcome measures (O) from which data was extracted were tools which reported intensity, quality or daily impact of breathlessness. These had to be measured on at least two occasions, two years apart from each other. METHODOLOGY Two basic groups of search terms were employed in the search. The first group concerned the identifying feature of the target population; a diagnosis of COPD. The second group of terms aimed to identify study designs which were likely to report data over the course of at least two years on a variety of respiratory related outcomes including the sensation of breathlessness. In order to ascertain as (...truncated)