Quantitative tool to evaluate the somatic burden due to chemotherapy-induced adverse events: the somatic burden score

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.

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).

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.

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.