Variability in objective and subjective measures affects baseline values in studies of patients with COPD.

TitleVariability in objective and subjective measures affects baseline values in studies of patients with COPD.
Publication TypePublication
AuthorsAnderson WH, Ha JWook, Couper DJ, O'Neal WK, R Barr G, Bleecker ER, Carretta EE, Cooper CB, Doerschuk CM, M Drummond B, Han MK, Hansel NN, Kim V, Kleerup EC, Martinez FJ, Rennard SI, Tashkin D, Woodruff PG, Paine R, Curtis JL, Kanner RE
Corporate AuthorsSPIROMICS Research Group
JournalPLoS One
Date Published2017
KeywordsAdult, Aged, Aged, 80 and over, Blood Cell Count, Exercise Test, Female, Humans, Male, Middle Aged, Prospective Studies, Pulmonary Disease, Chronic Obstructive, Reproducibility of Results, smoking, Spirometry, Surveys and Questionnaires, Time Factors, Tomography, X-Ray Computed

RATIONALE: Understanding the reliability and repeatability of clinical measurements used in the diagnosis, treatment and monitoring of disease progression is of critical importance across all disciplines of clinical practice and in clinical trials to assess therapeutic efficacy and safety.OBJECTIVES: Our goal is to understand normal variability for assessing true changes in health status and to more accurately utilize this data to differentiate disease characteristics and outcomes.METHODS: Our study is the first study designed entirely to establish the repeatability of a large number of instruments utilized for the clinical assessment of COPD in the same subjects over the same period. We utilized SPIROMICS participants (n = 98) that returned to their clinical center within 6 weeks of their baseline visit to repeat complete baseline assessments. Demographics, spirometry, questionnaires, complete blood cell counts (CBC), medical history, and emphysema status by computerized tomography (CT) imaging were obtained.RESULTS: Pulmonary function tests (PFTs) were highly repeatable (ICC's >0.9) but the 6 minute walk (6MW) was less so (ICC = 0.79). Among questionnaires, the Saint George's Respiratory Questionnaire (SGRQ) was most repeatable. Self-reported clinical features, such as exacerbation history, and features of chronic bronchitis, often produced kappa values <0.6. Reported age at starting smoking and average number of cigarettes smoked were modestly repeatable (kappa = 0.76 and 0.79). Complete blood counts (CBC) variables produced intraclass correlation coefficients (ICC) values between 0.6 and 0.8.CONCLUSIONS: PFTs were highly repeatable, while subjective measures and subject recall were more variable. Analyses using features with poor repeatability could lead to misclassification and outcome errors. Hence, care should be taken when interpreting change in clinical features based on measures with low repeatability. Efforts to improve repeatability of key clinical features such as exacerbation history and chronic bronchitis are warranted.

Alternate JournalPLoS ONE
PubMed ID28934249
PubMed Central IDPMC5608200
Grant ListI01 CX000911 / CX / CSRD VA / United States
U01 HL137880 / HL / NHLBI NIH HHS / United States
Manuscript Lead/Corresponding Author Affiliation: 
Genomics and Informatics Center (University of North Carolina at Chapel Hill)
Manuscript Status: