The HOW LONG trial is an international, multicenter, Phase IV randomized clinical trial evaluating the optimal duration of adjunctive systemic corticosteroids in immunocompromised adults with severe Pneumocystis jirovecii pneumonia (PCP) who demonstrate early clinical recovery. Participants who no longer require supplemental oxygen by day 10 of corticosteroid therapy are randomized to discontinue corticosteroids at day 10 (or hospital discharge, if earlier) versus continue corticosteroids for a total of 21 days. The trial assesses whether earlier discontinuation reduces steroid-related complications while maintaining clinical outcomes.

Adjunctive systemic corticosteroids are routinely used in severe PCP to reduce pulmonary inflammation and improve survival, but the recommended 21-day duration is based on limited historical evidence. Prolonged corticosteroid exposure may increase risks including secondary infections, hyperglycemia, gastrointestinal bleeding, and other adverse effects. The HOW LONG trial tests whether stopping corticosteroids earlier, after clinical recovery, improves net clinical outcomes.

Eligible adults with proven or probable severe PCP who have recovered to room air (no need for supplemental oxygen) for at least 6 hours by day 10 of corticosteroid therapy are enrolled and randomized centrally 1:1 in the MUHC Research Electronic Data Capture (REDCap) system to (1) discontinuation of corticosteroids at day 10 or hospital discharge or (2) continuation of corticosteroids to a total of 21 days. All participants receive standard antimicrobial therapy for PCP per treating clinicians. Follow-up occurs to day 180.

The primary endpoint is a hierarchical composite outcome assessed at day 60, incorporating mortality, relapse of PCP-related hypoxemia, secondary infections, severe metabolic or gastrointestinal complications, and length of hospital stay. Secondary endpoints include individual components of the composite outcome, and tertiary endpoints include quality of life and longer-term outcomes through day 180.

Inclusion Criteria:

• Age ≥18 years
• Proven or probable Pneumocystis jirovecii pneumonia
• Severe PCP requiring supplemental oxygen (e.g., ≥4 L/min or ≥35% FiO₂ to maintain SpO₂ ≥94%)
• Planned or receiving adjunctive systemic corticosteroid therapy for severe PCP
• Clinical recovery by day 10 of steroid therapy: breathing room air for ≥6 hours
• Able to provide informed consent (or per local requirements)

Exclusion Criteria:

• Persistent hypoxemia or ongoing oxygen requirement at day 10
• Clinical deterioration prior to randomization
• Treating clinician determines steroids must be continued or stopped immediately for medical reasons
• Anticipated death within 48 hours
• Inability or unwillingness to complete follow-up through day 180

Anonymized data will be made available upon reasonable request to the principal investigator by email (emily.mcdonald@mcgill.ca) subject to discussion surrounding the necessity of an interinstitutional data sharing agreement, commencing one year following the publication of the main trial results, for a period of 2 years.

1 year following main publication for a period of 2 years

investigators wishing to pursue secondary questions related to the data can contact emily.mcdonald@mcgill.ca for access to the data via a data sharing agreement.