Hutchings 2014.

Study characteristics
Methods	Secondary citation(s) NA Language of publication English Study design Prospective, multi‐centre study Study centre(s) Not reported Countries USA, Italy, Poland, Denmark Median follow‐up time (range) 29 months
Participants	Number of included participants 126* *Potential overlap of Danish participants with those included in Hutchings 2006 Inclusion criteria Newly diagnosed classic HL Exclusion criteria None Consent Yes; written Recruitment period Not reported Age (range, in years) 34.1 (median, 16.8‐76.7) Ethnic group(s) Not reported Stages of disease All stages Comorbidities Not reported Therapy regimen Early‐stage disease: 2‐4 cycles ABVD followed by radiotherapy, or 6 cycles ABVD Advanced‐stage disease: 6‐8 cycles ABVD with or without consolidation radiotherapy, with exceptions (5 Danish participants treated with BEACOPPesc)
Prognostic factor(s)	Prognostic factor(s) Interim PET Definition of prognostic factor(s) Whole‐body PET scan Timing of prognostic factor measurement Within the last 5 days of cycle 1 (PET1) and cycle 2 (PET2) (US and Italian participants had PET2 only if PET1 was positive) Method for measurement (use of specific scale and cut‐off) Deauville 5‐point scoring system Scores of 1‐3 considered negative, scores of 4‐5 considered positive Baseline interpretation by an expert with access to clinical information, second interpretation by an independent expert from another country blinded to clinical information Was the same definition and method for measurement used in all participants? No; not all participants received PET2 Were prognostic factor(s) assessed blinded for outcome(s), and for each other (if relevant)? Yes; experts in both stages blinded to clinical outcome, baseline experts also blinded to clinical information
Outcome(s)	Primary outcome(s) and definition(s) Progression‐free survival (PFS), not defined Overall survival (OS), not defined Secondary outcome(s) and definition(s) None Timing of outcome measurement At 2 and 3 years Was the same definition and method for measurement used in all participants? Not reported; unclear due to multi‐national study design Was/were outcome(s) assessed blinded for prognostic factor(s), and for each other (if relevant)? Not reported
Missing data	Participants with any missing value? No If yes, how were missing data handled? Not applicable
Analysis	Univariable analysis: Yes Total number of participants included in univariate analysis for each outcome PFS: all OS: all Statistical method Kaplan‐Meier (survival analysis) Log‐rank (differences between groups) How was the prognostic factor treated? Binary Multivariable analysis: Yes Total number of participants included in multivariable analysis for each outcome PFS: all OS: none Statistical method Kaplan‐Meier (survival analysis) Log‐rank (differences between groups) How was the prognostic factor treated? Binary Number of candidate covariates 3 List of all candidate covariates Interim PET (positive or negative) Extranodal involvement Disease stage (early or advanced stage)
Risk of bias (QUIPS)	Study participation Low risk Description of participants and study characteristics given. No inclusion and exclusion criteria. Consecutive sampling and no exclusion based on interim PET availability. Detailed description of treatment regimen. Study attrition Low risk No loss to follow‐up. Prognostic factor measurement Low risk Adequate measurement and description. Prognostic factor measured the same way for all participants. Outcome: Overall survival Outcome measurement Low risk Adequate measurement and description. Prognostic factor measured the same way for all participants. 'Other prognostic factors (covariates)' High risk Disease stage not accounted for. Statistical analysis and reporting Low risk Statistical method in univariable analysis appropriate for the data. Outcome: Progression‐free survival Outcome measurement Low risk No definition of outcome. Outcome measured the same way for all participants. 'Other prognostic factors (covariates)' High risk Disease stage not accounted for. Statistical analysis and reporting Low risk Statistical method in univariable analysis appropriate for the data. Outcome: Adverse events Not reported
Notes	Conflict of interest The author(s) indicated no potential conflicts of interest. Funding Not reported