The Steroid Symptom Questionnaire Multiple Myeloma (SSQ-MM): translation and cross-cultural adaptation into Danish and Norwegian and initial psychometric evaluation of the Norwegian version.

The SSQ-MM was translated and culturally adapted into Danish and Norwegian, and both versions were considered relevant and acceptable by patients and clinicians.

• Translation and cultural adaptation followed ISPOR good practice guidelines.
• The process included forward-backward translation and cognitive debriefing interviews with patients and clinicians.
• The questionnaire assesses patient-reported side effects of corticosteroid treatment in multiple myeloma (MM) patients.

The Norwegian SSQ-MM showed acceptable internal consistency for the total score and the psychological subscale.

• Cronbach's alpha was 0.74 for the total score.
• Cronbach's alpha was 0.81 for the psychological subscale.
• The psychometric evaluation was conducted in newly diagnosed Norwegian MM patients receiving weekly dexamethasone.

Construct validity of the Norwegian SSQ-MM was supported, as correlation patterns with EORTC QLQ-C30 constructs were generally consistent with predefined hypotheses.

• Construct validity was explored through correlations with EORTC QLQ-C30 constructs.
• Correlations were described as 'generally consistent' with hypotheses, not fully consistent in every case.

Known-groups validity was supported by differences in SSQ-MM symptom scores according to ECOG performance status.

• Known-groups comparisons were based on ECOG performance status.
• Symptom scores differed between performance status groups.

The Norwegian SSQ-MM was responsive during dexamethasone treatment, with significant increases in total score and several steroid-related symptoms, but fewer changes after treatment discontinuation.

• Responsiveness was evaluated across three time points.
• Significant increases were seen in the total score and several individual steroid-related symptoms during treatment.
• Fewer changes were observed following treatment discontinuation.

Symptom levels in the Norwegian cohort were lower overall than those reported in the original Australian validation study.

• The comparison was made against the original Australian validation study of the SSQ-MM.

The findings provide only preliminary evidence of reliability, construct validity, known-groups validity, and responsiveness of the Norwegian SSQ-MM, and larger studies are needed.

• The authors call for further studies in larger, diverse MM populations to evaluate measurement properties.