GOLD | Classification of COPD based on the degree of airflow obstruction (up to 2011), in combination with symptoms/exacerbations (2011–2017), or symptoms/exacerbations only (2017) | From an FEV1 centric view to a more extensive approach and a more prominent role of symptoms/individual measures [13] | Parameters assessing COPD severity still very limited; ignoring variability and unpredictability of symptoms/exacerbations/hospitalisations; proposed cut-off points for symptom measures mostly expert driven | Separation of airflow limitation from clinical parameters (GOLD 2017) [9] clarifies what is being evaluated and ranked and might facilitate more precise treatment | Not addressed |
Multidimensional indices | Prognostic indices to predict survival; screening instruments | As prognostic markers: useful in grouping patients in terms of clinically relevant outcomes [14]; as a screening instrument: multidimensional assessment of COPD [11, 15] | Identification of substitute groups or phenotypes only by selected variables included in the respective index; consist of a limited number of variables; have not been developed to guide future treatment [16] | Multidimensional assessment, including, for example, medical, pathophysiological, symptomatic [14] and/or psychological [15] parameters | Not addressed |
Phenotypes | Grouping patients based on certain characteristics | From “blue bloater” and “pink puffer” to complex cluster analyses identifying existing and novel phenotypes | Cluster analyses only moderate reproducibility, clinical application disputable [17], considerable overlap between phenotypes for some specific attributes | As a screening instrument: differentiating between individuals by assessing/clustering various characteristics | Not addressed |
COPD control panel | Assessment of different elements of the disease | Assessing at least three dimensions (severity, activity and impact), can be customised to the need of the patient [18] | Unclear which characteristics should exactly be assessed, which methods, cut-off points, etc. should be used | Multidimensional assessment; might serve as a “clinical decision support system” (by selecting/classifying patients) | Not addressed |
Treatable traits | Label-free, precision medicine approach | COPD management based on individual treatable characteristics (intra- and extrapulmonary treatable traits, treatable behaviour/lifestyles (including patients’ environment)) [19] | Separate assessment of treatable traits results in fragmented treatment; frequency of assessment and inter-relationships between traits unknown | Assessing heterogeneity by individual unique traits | Not addressed |
Pulmonary rehabilitation | Personalised, holistic approach of treatable traits | Comprehensive intervention based on a thorough assessment taking into account the combination and interaction between the (treatment of) individual treatable traits [20] | Applicability in routine clinical practice (dependent on organisational structure, facilities, workforce, funding, etc.) is challenging; poor referral and compliance; not all traits are always addressed (yet); mostly non-pharmacological generic interventions | Assessing heterogeneity by individual unique traits | Assessment of complex interactions of physical, psychological, social and environmental factors by dedicated, transdisciplinary teams being able to respond flexibly as well as accept unpredictability and non-linear outcomes [21] |