Protocol, rationale and design of the PHOLLOW cross-sectional and retrospective chart review study to assess the prevalence and characterize the patient profile, clinical features and disease burden of type-2 low severe asthma in routine care settings in Greece.

Type 2 (T2)-low severe asthma (SA) presents a distinct subpopulation for which, in lack of a consistent classification system, epidemiological and clinical outcome data remain unclear and therapeutic needs remain largely unmet. The aim of the PHOLLOW real-world study is to assess the prevalence and predictors of T2-low SA, and depict the patient profile, clinical features, treatment patterns and disease burden using clinical and patient-reported outcomes (PROs) in routine settings in Greece. This is a cross-sectional and retrospective chart review 2-part study that will enroll 600 adult outpatients with SA over a 1-year period by 20-30 asthma specialists. A new SA phenotype classification system and two different definitions proposed herein will be used to categorize patients into definite or possible T2-low (unlikely or least likely T2-high) SA, and definite/most likely or possible/likely T2-high SA, based on a composite measure of airway inflammation markers (blood eosinophil counts, fractional exhaled nitric oxide), allergic/atopic status and age-of-onset phenotype, taking into consideration the current receipt of biologic and/or maintenance oral corticosteroid treatment and response to it. Part A will collect top-level data for all participants to assess T2-low SA prevalence and predictors. T2-low SA patients will proceed to part B, where further data and PROs assessing asthma symptom control, quality of life, anxiety, depression, work productivity and activity impairment will be collected. In view of anticipated new treatments for SA, evidence generated by PHOLLOW will provide insight into T2-low SA prevalence and disease burden, using a well-defined classification scheme, which can inform healthcare decisionmaking. [ABSTRACT FROM AUTHOR]