This study evaluated an MM-specific module of the MDASI in patients undergoing treatment for MM. Our results provide strong psychometric evidence that the MDASI-MM is a valid, reliable instrument that can discriminate between clinically different patient groups and that has high sensitivity in detecting symptom change during treatment with respect both to patients’ ECOG PS and evolving symptom trajectories. Individual items and subscales of the MDASI-MM correlated strongly with corresponding items and subscales of the EORTC QLQ C-30 and QLQ MY-20. Cognitive debriefing evidenced that the MDASI-MM is easy to understand, quick to complete, and comprehensive.
One of the most useful assets of the MDASI-MM is its brevity. For example, it captured 4 of the top 5 symptoms captured by the 2 EORTC instruments. Thus, although brief, it captures patients’ most critical symptoms with minimal patient burden. Additionally, unlike the MDASI-MM, the 2 EORTC instruments are QOL scales that were not developed within the conceptual framework of symptom assessment [7
]. As the QLQ C-30 must be administered with the QLQ MY-20 (a total of 50 items, compared with 26 items in the MDASI-MM), this adds substantially to patient burden. The MDASI-MM’s brevity also allows for efficient repeat administrations for charting a patient’s symptom trajectory over the course of treatment, which is a valuable aid to clinical decision making. Previous research indicates that patient-reported outcome measures can be effective guides to key clinical decisions [27
], especially when objective evaluations of physical indices are difficult [28
A significant advantage of MDASI modules is that each module includes all symptom and interference items from the original MDASI. Each module validation subjects the original MDASI items to further cognitive debriefing and sensitivity testing by additional patients, reinforcing the validity, reliability, and sensitivity of the original instrument. Original items can thus be included in new modules with fewer psychometric steps, enabling efficiency and cost savings in the development of disease-specific modules. Also, because each new module includes the original MDASI items, the use of MDASI modules facilitates comparison of symptom prevalence and severity across cancer types, a significant benefit in clinical trials or studies that include patients with different cancers.
During cognitive debriefing, 1 patient reported 2 symptoms not present in the MDASI-MM module (swelling/edema and transient night sweats). These items were not included in the final instrument as they were extremely rare [16
]. If these items are reported in the literature with greater frequency, it may be reasonable to include them in a future revision of the MDASI-MM.
A limitation of our study was its largely racially homogenous population; future work is needed to test patients of diverse backgrounds in various treatment settings. Another limitation is that although we were able to demonstrate the sensitivity of the MDASI-MM to change in performance status and to impact of therapy, we were unable to demonstrate its sensitivity to change in patients’ disease status (eg, stable or progressive disease; partial or very good partial response) as these data were not available. Our key strengths include the development of an instrument based on symptom burden rather than health-related QOL, and inclusion of both induction and transplant patients, which extends its generalizability.