Derivation and validation of clinical phenotypes for XXXX : a systematic review.

@entity1 @entity1576 @entity28 @entity1030
BACKGROUND: The traditional classification of @entity1030 , which relies solely on spirometry, fails to account for the complexity and heterogeneity of the disease. Phenotyping is a method that attempts to derive a single or combination of disease attributes that are associated with clinically meaningful outcomes. Deriving phenotypes entails the use of cluster analyses, and helps individualize @entity1 management by identifying groups of individuals with similar characteristics. We aimed to systematically review the literature for studies that had derived such phenotypes using unsupervised methods. METHODS: Two independent reviewers systematically searched multiple databases for studies that performed validated statistical analyses, free of definitive pre-determined hypotheses, to derive phenotypes among @entity1 with @entity1030 . Data were extracted independently. RESULTS: 9156 citations were retrieved, of which, 8 studies were included. The number of subjects ranged from 213 to 1543. Most studies appeared to be biased: @entity1 were more likely males, with severe disease, and recruited in tertiary care settings. Statistical methods used to derive phenotypes varied by study. The number of phenotypes identified ranged from 2 to 5. Two phenotypes, with poor longitudinal health outcomes, were common across multiple studies: young @entity1 with severe @entity1576 , few cardiovascular co-morbidities, poor nutritional status and poor health status, and a phenotype of older @entity1 with moderate @entity1576 , @entity28 , cardiovascular and metabolic co-morbidities. CONCLUSIONS: The recognition that two phenotypes of @entity1030 were often reported may have clinical implications for altering the course of the disease. This review also provided important information on limitations of phenotype studies in @entity1030 and the need for improvement in future studies.
