BACKGROUND: Since the benefit-harm balance of adding inhaled corticosteroids to long-acting β2-agonists (LABA) and long-acting muscarinic antagonists (LAMA) for patients with chronic obstructive pulmonary disease is unclear, we evaluated this addition for a range of patient profiles. METHODS: Analyses considered the effects of low-to-moderate doses of inhaled corticosteroids, LABA, and LAMA compared with LABA and LAMA alone, outcome incidences, and preference weights assigned to averted moderate-to-severe exacerbations (benefit) and severe pneumonia, candidiasis, and dysphonia (harm). Using exponential models, we estimated the preference weight-adjusted 2-year net clinical benefit (ie, benefits outweighing harms) indices. Exacerbation risk thresholds for triggering inhaled corticosteroids, LABA, and LAMA were established when the probability of a 2-year net clinical benefit reached 60%. We estimated the proportion of patients benefiting from added inhaled corticosteroids using an externally validated prediction model for acute exacerbations in primary care. FINDINGS: Adding low-to-moderate dose inhaled corticosteroids to LABA and LAMA provided a net clinical benefit in patients with a 2-year baseline exacerbation risk of 54-83%. Low-dose inhaled corticosteroids showed a net clinical benefit if the baseline risk was 40-91%, but not at higher doses. The benefit was modified by blood eosinophil count (BEC) and age. Although no net benefit was associated with a BEC of less than 150 cells per μL, patients with a BEC of 150 cells per μL or more had a net benefit from low-dose inhaled corticosteroids with a 2-year exacerbation risk of 32-95% in those aged 40-79 years and 41-93% in those older than 80 years. A moderate dose of inhaled corticosteroids showed a net benefit in patients younger than 80 years with a BEC of 150 cells per μL or more at 52-86% 2-year exacerbation risk. Depending on the subgroups, the proportion of patients with a net benefit from added inhaled corticosteroids ranged from 0 to 68%. INTERPRETATION: The net clinical benefit of adding different inhaled corticosteroid doses to LABA and LAMA varies greatly with exacerbation risk, BEC, and age. Personalised treatment decisions based on these factors and predicted exacerbation risks might reduce overtreatment and undertreatment with inhaled corticosteroids.None.