TABLE 1

Selected markers that could be used to determine the natural history of patients with chronic obstructive pulmonary diseases

Strength of evidenceValue in helping to determine disease extentCommentRef.
Physiological
 Spirometry (FEV1 and FVC)AAGold standard of disease severity and progression[33, 34, 48–50, 60]
 Lung volumesCAClinically valid
Poor data about use over time
[70–72]
 Diffusion capacity for COCAClinically valid
Poor data about its natural course
[73]
Imaging
 Chest radiographyABClinically valid
Poor data bout its natural course
[74]
 Chest tomographyAAClinically valid
Some data over time
Useful for emphysema
[74–79]
Functional Capacity
 Timed walking distanceAAPredictor of outcome
Moderate evidence of longitudinal change
[80, 81]
 Cardiopulmonary exercise testAAUseful to determine reserve and endurance
No longitudinal data
[70, 82]
Perceptive domain
 Dyspnoea scalesAAPredictors of outcome
Significant data about its change over time
[83–85]
 Health status or quality of lifeAAGood determinant of disease effect
Good data for evolution over time
[65, 66, 86]
Biomarkers
 SystemicBCNo biomarker has been identified as clinically useful[87–89]
 Breath condensateCCLimited experimental use[87]
Multidimensional
 BODEAAPredicts outcome
Some longitudinal data, supports its clinical use
[55, 90–92]
 ADOBBPredicts outcome
No longitudinal data
[55]
 DOSEBBPredicts outcome
No longitudinal data
[93]

Strength of evidence (A–C): this strength represents the evidence from the literature. Value for helping to determine disease extent (A–C): this qualifier relates to the help it offers to evaluate disease extent. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; BODE: body mass index, obstruction, dyspnoea and exercise; ADO: age, dyspnoea and obstruction index; DOSE: dyspnoea, obstruction, smoking and exacerbations.