Adjusting for COPD severity in database research: developing and validating an algorithm.

Int J Chron Obstruct Pulmon Dis. 2011;6:669-78

Authors: Goossens LM, Baker CL, Monz BU, Zou KH, Mölken MP

Abstract
PURPOSE: When comparing chronic obstructive lung disease (COPD) interventions in database research, it is important to adjust for severity. Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines grade severity according to lung function. Most databases lack data on lung function. Previous database research has approximated COPD severity using demographics and healthcare utilization. This study aims to derive an algorithm for COPD severity using baseline data from a large respiratory trial (UPLIFT).
METHODS: Partial proportional odds logit models were developed for probabilities of being in GOLD stages II, III and IV. Concordance between predicted and observed stage was assessed using kappa-statistics. Models were estimated in a random selection of 2/3 of patients and validated in the remainder. The analysis was repeated in a subsample with a balanced distribution across severity stages. Univariate associations of COPD severity with the covariates were tested as well.
RESULTS: More severe COPD was associated with being male and younger, having quit smoking, lower BMI, osteoporosis, hospitalizations, using certain medications, and oxygen. After adjusting for these variables, co-morbidities, previous healthcare resource use (eg, emergency room, hospitalizations) and inhaled corticosteroids, xanthines, or mucolytics were no longer independently associated with COPD severity, although they were in univariate tests. The concordance was poor (kappa = 0.151) and only slightly better in the balanced sample (kappa = 0.215).
CONCLUSION: COPD severity cannot be reliably predicted from demographics and healthcare use. This limitation should be considered when interpreting findings from database studies, and additional research should explore other methods to account for COPD severity.

PMID: 22259243 [PubMed - in process]

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It is a common clinical experience that patients with chronic obstructive pulmonary disease (COPD) complain of airway symptoms provoked by environmental irritants like chemicals and scents, although few studies can confirm such connections.

The aim was to study the prevalence of airway symptoms induced by chemicals and scents in a group of patients with newly diagnosed CPOD and to analyze any relation to illness severity and quality of life. Eighty-one patients with COPD were recruited to the study. By mail they were asked to answer three questionnaires regarding symptoms, quality of life, and social and emotional influence of airway symptoms induced by environmental irritants. A majority (62%) of the COPD patients claimed to be hyperreactive to chemicals and scents. As a group they scored higher on a questionnaire measuring social and emotional influences of such environmental irritants compared to healthy control subjects. Further, high scores were more common among patients with a very severe form of COPD and among patients with regular use of β(2)-stimulants. High scores were also associated with significantly more airway symptoms and, in some aspects, with impaired quality of life.

In conclusion, the results of this study show that airway symptoms induced by environmental irritants are common in patients with COPD and that this increased airway sensitivity follows the impairment of lung capacity. The mechanisms behind this remain unclear.

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Chronic obstructive pulmonary disease (COPD) patients with mucus hypersecretion tend to demonstrate increased frequency of infective exacerbations and a steeper slope of decline in lung function. Enhanced mucociliary clearance with high-frequency chest wall oscillation (HFCWO) devices previously used in cystic fibrosis and bronchiectasis patients may offer the opportunity for community-based, self-managed therapy to improve quality of life and lung function.

STUDY DESIGN AND METHODS: A randomized controlled crossover pilot study of HFCWO compared with conventional treatment was conducted in 22 patients with moderate to severe COPD and mucus hypersecretion. Patients spent 4 weeks using an HFCWO (SmartVest(®)) device and 4 weeks in a conventional phase with a 2-week washout. Eleven patients started with HFCWO and changed to conventional treatment, whereas the other eleven patients started conventional treatment and crossed over to HFCWO.

RESULTS: The patients were elderly with a mean age of 71 (standard deviation [SD] 10) years and were at the upper end of the normal range of body mass index (25 [SD 4.2] kg/m(2)). The majority of patients had moderate to severe COPD with a mean percentage predicted forced expiratory volume in 1 second of 41 (SD 15.6) and percentage predicted forced vital capacity of 73 (SD 17.7). Baseline sputum production was negatively correlated to lung function and positively to St George's Respiratory Questionnaire. Symptom scores and St George's Respiratory Questionnaire symptom dimension improved significantly (-8, P < 0.05). Sputum production showed a declining trend in the HFCWO phase, although not reaching statistical significance. The HFCWO device was well tolerated with good reported compliance.

CONCLUSION: This pilot study demonstrated that patients with advanced COPD and mucus hypersecretion at increased risk of declining lung function tolerated the HFCWO treatment well, leading to improvement in quality of life and reduced symptoms.

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Chronic obstructive pulmonary disease (COPD) is a crippling disease with a high worldwide prevalence. The purpose of this review is to highlight recent studies which define the global impact of COPD on quality of life. There are direct implications for care.

RECENT FINDINGS: Dyspnea is a dominant and defining symptom for patients with COPD, but the overall degree of impairment suffered by patients with COPD extends far beyond shortness of breath. A series of recent studies gives us insight into both the physical and the psychosocial burdens of the disease and their negative net effects upon quality of life. The suffering of patients with COPD is similar to that of patients with cancer, and palliative measures have been shown to be an important component of comprehensive care.

SUMMARY: The symptom burden in patients with severe COPD is high and is comparable to that of patients with cancer. Ironically, patients with COPD could be said to suffer more than those with cancer; the symptom burden is similar, but patients with COPD tend to live longer. The literature is replete with evidence that a palliative care approach to patients with cancer increases the quality of life (and perhaps even the quality of death). The same palliative care approach can and should be used for patients with COPD. There are now objective data to support the benefits of such an approach.

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