Quantitative Tool to Evaluate the Somatic Burden Due to Chemotherapy-induced Adverse Events: the Somatic Burden Score

Purpose: Although there are several established methods like the Common Terminology Criteria for Adverse Events (CTCAE), heretofore, no objective, quantitative measurement exists for the somatic burden due to chemotherapy-induced adverse events (SB-CHINAE). We developed the Somatic Burden Score (SBS-AE) that combines the severity grade and duration of an AE. This paper describes the development and validation of the SBS-AE.

Methods: SBS-AE's calculation was based on the number of days of CTCAE grades of a particular AE. The target value was the weighted, relative duration of an AE grade using CTCAE v3.0. We applied the SBS-AE in 64 patients with hematological malignancies and high-dose chemotherapy (HDC). The ratio measurement scale of the SBS-AE allows all statistical measures using SBS-AE, as all necessary mathematical operations are defined for it. We calculated an overall-SBS-HDC, defined as the total SB-CHINAE of HDC. To determine SBS-AE's criterion and construct validity, three self-rating scales and one clinician rating scale were used (German Clinical Trials Register, Main ID: DRKS00003453).

Results: The SBS-AE's criterion validity could be verified both with statistical significance and at least medium-to-large effects (p < 0.05, Cohen's d > 0.79, f (2) > 0.18). The quantitative measured SB-CHINAE was equally associated with subjectively assessed physical health-related quality of life (0.15 ≤ R (2) ≤ 0.49), objectively evaluated toxicities (0.48 ≤ R (2) ≤ 0.67), transfusion-dependent thrombocytopenia, and anemia (Cohen's d > 0.89). Patients' somatic burden of HDC was 5.8-fold greater compared with standard chemotherapy regimens.

Conclusions: The SBS-AE indicates psychometric and clinical properties and may prove useful in the future design of cancer clinical trials and supportive care interventions inside of the inpatient setting.