Evaluating Concordance between International Myeloma Working Group (IMWG) and Simplified Frailty Index (SFI) Among Older Adults with Multiple Myeloma (MM)

Introduction: Despite significant advances in therapeutics, older adults with MM are at increased risk of treatment related toxicity and mortality. Frailty is an aging-associated state of cumulative decline in many physiological systems, resulting in diminished resistance to stressors, including cancer therapy. In 2015, the International Myeloma Working Group (IMWG) developed a geriatric assessment (GA) based frailty index (IMWG-FI) using age, comorbidities, and physical function (instrumental activities of daily living, IADL; activities of daily living, ADL) to predict risk of toxicity and mortality among older adults with MM (Palumbo, et al., Blood 2015). However, GA is not routinely incorporated in clinical practice and a simplified frailty index (SFI; Facon et al Leukemia 2020) has been proposed as an alternative to using ECOG performance status (ECOG PS) as a proxy for physical function (IADL/ADL). However, the concordance between IMWG-FI and SFI remains relatively unknown, as well as their predictive ability in clinical practice, particularly among patients with relapsed, refractory multiple myeloma (RR-MM). Our goal was to describe the prevalence of frailty using IMWG-FI and SFI as well as evaluate their concordance among patients with newly-diagnosed (ND) and RR-MM.

Methods: The Cancer and Aging Resilience Evaluation in Hematologic Malignancies (CARE-Heme) Registry is an ongoing prospective registry enrolling adults ≥50 years of age with a diagnosis of a hematologic malignancy undergoing treatment at a single institution. For this analysis, we included patients ≥50yo with ND- or RR-MM initiating a new treatment regimen (ranging from first to sixth line of treatment). All of the patients included in this study underwent a comprehensive GA prior to beginning a new line of therapy or stem cell transplant. We abstracted physician reported ECOG PS and comorbidities by reviewing medical records. We calculated IMWG frailty score as well as SFI using published methods. Each patient was categorized into frail/non-frail using the IMWG frailty score (fit, intermediate-fit, frail; collapsing fit/intermediate fit into the non-frail category) and the simplified frailty score (non-frail, frail) using published cutoffs. We measured the agreement between the total frailty scores using Spearman Correlation Coefficient and the frail/non-frail categorization using the Kappa statistic. Relevant treatment outcomes including progression-free survival, overall survival, and grade 2-5 toxicities (both hematologic and non-hematologic) were recorded until disease progression, death, or 6 cycles of treatment were completed.

Results: A total of 146 adults with MM (49 ND-MM, 51 pre-transplant, and 46 RR-MM) starting a new line of therapy or ASCT between 8/2020 to 1/2022 were included in this study. The median age was 62 (IQR 57-70) with 53% males and 36% blacks. Most patients had IgG isotype (64%) with International Staging System (ISS) stage III disease (38%) whereas 30% patients had high risk cytogenetics. The distribution by IWMG Frailty category was as follows: 43% fit, 32% intermediate-fit, and 25% frail. Using SFI, 32% of patients were characterized as frail and 68% were characterized as non-frail (Figure 1). Although, the frailty scores were well correlated with each other (Spearman rho 0.67, p value <.001), the agreement between SFI and IMWG-FI in terms of frailty categorization was moderate (Kappa statistic 0.50); 79% of patients were classified in the same frailty group, however about 21% of patients were characterized in different frailty categories using the two scales (Table 1). SFI over-estimated frailty in about 14% of patients. There was very little agreement between a patient-reported vs physician rated ECOG-PS (Kappa statistic 0.13). The discordance between the two FI worsened if a patient reported version of ECOG PS (Kappa statistic 0.30) was used.

Conclusions: Among older adults with MM, the prevalence of frailty ranged 25% by IMWG-FI to 32% by SFI. There was only a modest agreement between SFI and IMWG FI, which was worse when using patient reported version of ECOG PS. Studies comparing outcomes across the two frailty indices should take into account the potential for misclassification bias.

Bal:Adaptive Biotechnologies: Consultancy. Costa:Genentech: Research Funding; Adaptive Biotechnologies: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; AbbVie: Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding. Giri:Pack Health: Research Funding; OncLive: Honoraria; CareVive: Honoraria, Research Funding.