Objectives

The SPIROMICS study sought to identify homogeneous subgroups of COPD patients for targeted enrollment in future therapeutic clinical trials, as well as to identify and conduct preliminary validation of intermediate biological or clinical outcomes for use as clinical trial endpoints.

Background

Chronic obstructive pulmonary disease (COPD) is a chronic, usually progressive, lung disease characterized by incompletely reversible airflow obstruction. At the time of the SPIROMICS study, COPD affected between 12,000,000 and 24,000,000 people in the US, with no proven medical therapies that significantly reduce mortality, other than supplemental oxygen and smoking cessation. COPD is also a highly heterogeneous disease. For example, cigarette smoke-induced chronic bronchitis and emphysema are subsumed within the COPD definition, despite histological and clinical differences. The recognition of COPD as a systemic disease that affects extra-pulmonary systems, including cardiovascular, sleep and muscle function, further complicates disease classification. Because of clinical and pathological heterogeneity, individual patient subtypes may benefit from unique therapeutic regimens. Thus the SPIROMICS study was initiated to facilitate the identification of important COPD phenotypes, based on disease pathophysiology and biomarkers that track key pathophysiologic processes, in order to focus research efforts and improve treatment options.

Subjects

Eligible participants were between 40 and 80 years of age, and included never-smokers, current and former smokers without obstructive lung disease, and current and former smokers with COPD. Never smoker was defined as less than 1 pack-year smoking history, and current or former smoker were defined as more than 20 pack-years smoking history. Lung function was also part of the eligibility criteria and was assessed by spirometry with or without inhaled bronchodilators. Non-smokers were required to have pre-bronchodilator FEV1 (forced expiratory volume in one second)/FVC (forced vital capacity) > 0.7 and FVC > LLN (lower limit of normal). Current or former smokers without obstructive lung disease were required to have post-bronchodilator FEV1/FVC > 0.7 and FVC > LLN. Current or former smokers with obstructive lung disease were required to have post-bronchodilator FEV1/FVC < 0.7 and FEV1 > 50% predicted.

Major exclusion criteria included non-COPD obstructive lung disease or a history of diseases or treatments likely to interfere with interpretation of study tests, BMI > 40 kg/m2 at baseline, hypersensitivity to or intolerance of the bronchodilators used in study assessments, and diagnosis of unstable cardiovascular disease.

Design

SPIROMICS was a prospective cohort study that enrolled approximately 2,981 participants at twelve clinical centers over five years. Participants were distributed across four enrollment strata; never-smokers, smokers without COPD, smokers with mild or moderate COPD, and smokers with severe COPD.

There were baseline (Visit 1) and three annual in-person follow-up visits (Visits 2–4). Participants also received quarterly follow-up calls to assess health status and determine if an exacerbation occurred. Visits 1, 2 and 4, included anthropometry, seated blood pressure, spirometry, 6-minute walk test, biological specimen collection, and a series of questionnaires. Information was collected on medical history, respiratory exposures and current medications. Visits 1 and 2 included a thoracic computed tomography (CT) scan at maximum inspiration and expiration.

Clinical outcomes, including hospitalizations and deaths, were adjudicated centrally. The primary outcome measures up to month 36 were (1) morbidity measured by assessing acute exacerbations, (2) lung function by using spirometry and plethysmography to measure FEV1, FVC, FRC (functional residual capacity), and IC (inspiratory capacity), and (3) mortality.

There were several key sub-studies involving SPIROMICS participants. The Repeatability and Replicate Sub-study enrolled 98 participants and repeated the entire baseline clinic visit, including the CT scanning, in order to quantify reliability and short-term within-person variability of study procedures and assay methods. In addition, sites collected blinded replicate samples on 5% of each specimen type at the Baseline, Year 1, and Year 3 visits. The Bronchoscopy Sub-study enrolled a total of 250 subjects to undergo bronchoscopy with bronchoalveolar lavage, epithelial brushings and bronchial biopsies. The Exacerbation Sub-study enrolled a total of 214 participants that were followed prospectively and had biological samples and clinical information collected at the time of an acute exacerbation.

David Couper et al. Design of the subpopulations and intermediate outcomes in COPD study (SPIROMICS). Thorax. 2014;69(5):492–495.

Additional Details

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