Development and Validation of a Survey-Based COPD Severity Score

doi:10.1378/chest.127.6.1890

Chest

Volume 127, Issue 6, June 2005, Pages 1890-1897

https://doi.org/10.1378/chest.127.6.1890 Get rights and content

Objective

To develop a comprehensive disease-specific COPD severity instrument for survey-based epidemiologic research.

Study design and setting

Using a population-based sample of 383 US adults with self-reported physician-diagnosed COPD, we developed a disease-specific COPD severity instrument. The severity score was based on structured telephone interview responses and included five overall aspects of COPD severity: respiratory symptoms, systemic corticosteroid use, other COPD medication use, previous hospitalization or intubation, and home oxygen use. We evaluated concurrent validity by examining the association between the COPD severity score and three health status domains: pulmonary function, physical health-related quality of life (HRQL), and physical disability. Pulmonary function was available for a subgroup of the sample (FEV₁, n = 49; peak expiratory flow rate [PEFR], n = 93).

Results

The COPD severity score had high internal consistency reliability (Cronbach α = 0.80). Among the 49 subjects with FEV₁ data, higher COPD severity scores were associated with poorer percentage of predicted FEV₁ (r = − 0.40, p = 0.005). In the 93 subjects with available PEFR measurements, greater COPD severity was also related to worse percentage of predicted PEFR (r = − 0.35, p < 0.001). Higher COPD severity scores were strongly associated with poorer physical HRQL (r = − 0.58, p < 0.0001) and greater restricted activity attributed to a respiratory condition (r = 0.59, p < 0.0001). Higher COPD severity scores were also associated with a greater risk of difficulty with activities of daily living (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.8 to 3.0) and inability to work (OR, 4.2; 95% CI, 3.0 to 5.8).

Conclusion

The COPD severity score is a reliable and valid measure of disease severity, making it a useful research tool. The severity score, which does not require pulmonary function measurement, can be used as a study outcome or to adjust for disease severity.

Section snippets

Overview

In a population-based sample of 383 US adults with COPD, we developed a disease-specific COPD severity instrument. The severity score was based on responses to a structured telephone interview. Internal consistency reliability was established using standard psychometric techniques. We evaluated concurrent validity by examining the association between the COPD severity score and three aspects of health status: pulmonary function, physical HRQL and health status, and physical disability.

Subject Characteristics

The mean age of subjects with COPD was 64 ± 6 years (Table 2). The majority of subjects had a lifetime history of cigarette smoking (81%). Other sociodemographic characteristics are shown in Table 2.

COPD Severity Score

The COPD severity score ranged from 0 to 28 (mean, 7.3 ± 6.5; median, 6.0; 25th to 75th interquartile range, 2 to 25). The COPD severity score, which was based on an a priori weighting system, correlated very closely with the score whose alternative weighting was derived from factor analysis with

Discussion

In this population-based study, we developed a survey-based COPD severity score that incorporates clinical aspects of the disease, including respiratory symptoms, oral corticosteroid use, other COPD medication use, previous hospitalization and intubation, and home oxygen therapy. The COPD severity score is internally consistent, reliable, and appears to capture a broad range of disease severity. We have demonstrated the concurrent validity of the COPD severity score using diverse measures of

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Patients (N = 902) with early-stage (stage IA-IIB) NSCLC treated with surgical resection were retrospectively analyzed. The association of self-reported, physician-diagnosed COPD with survivals of NSCLC was assessed using the log-rank and Cox regression models, adjusting for age, sex, BMI, smoking, stages, and performance status.
Among this cohort of patients with NSCLC, 330 cases had physician-diagnosed COPD, and 572 did not have COPD. The 5-year OS in patients with COPD (54.4%) was significantly lower (P = .0002) than that in patients without COPD (69.0%). The 5-year PFS rates for patients with COPD and without COPD were 50.1% and 60.6%, respectively (P = .007). Compared with patients without COPD, patients with COPD had increased risk of worse OS (adjusted hazard ratio [HRadj] = 1.41, P = .002) and PFS (HRadj = 1.67, P = .003). The associations between COPD and worse survival outcomes were stronger in men and in squamous cell carcinoma (SCC).
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Studies that included a measure of ADLs in individuals with COPD were identified using electronic and hand searches. Two investigators performed the literature search. One investigator reviewed the study title, abstract, and full text of the articles to determine study eligibility and performed the data extraction and tabulation. In cases of uncertainty, a second reviewer was consulted.
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Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

Support was provided by grant R01 HL607438 from the National Heart, Lung, and Blood Institute, National Institutes of Health, and Flight Attendants Medical Research Institute grant CoE2001. Dr. Eisner was also supported by grant K23 HL04201 from the National Heart, Lung, and Blood Institute.

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Chest

Clinical InvestigationsDevelopment and Validation of a Survey-Based COPD Severity Score

Objective

Study design and setting

Results

Conclusion

Section snippets

Overview

Subject Characteristics

COPD Severity Score

Discussion

Chest

J Clin Epidemiol

Chest

Am J Med

Chest

Chest

Chest

Chronic obstructive pulmonary disease surveillance–United States, 1971–2000

MMWR Surveill Summ

BTS guidelines for the management of chronic obstructive pulmonary disease. The COPD Guidelines Group of the Standards of Care Committee of the BTS

Thorax

American Thoracic Society. Standards for the diagnosis and care of patients with chronic obstructive pulmonary disease

Am J Respir Crit Care Med

Optimal assessment and management of chronic obstructive pulmonary disease (COPD). The European Respiratory Society Task Force

Eur Respir J

Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary

Am J Respir Crit Care Med

Global strategy for the diagnosis, management and prevention of COPD: 2003 update

Eur Respir J

Chronic obstructive pulmonary disease mortality in six U.S. cities

Am Rev Respir Dis

Randomised, double blind, placebo controlled study of fluticasone propionate in patients with moderate to severe chronic obstructive pulmonary disease: the ISOLDE trial

BMJ

Lung Health Study Research Group. Effect of inhaled triamcinolone on the decline in pulmonary function in chronic obstructive pulmonary disease

N Engl J Med

Inhaled glucocorticosteroids and chronic obstructive pulmonary disease: how full is the glass?

Am J Respir Crit Care Med

Effects of fluticasone propionate in COPD patients with bronchial hyperresponsiveness

Thorax

Clinical Investigations
Development and Validation of a Survey-Based COPD Severity Score