Cumulative Deficits Frailty Index and Relationship Status Predict Survival in Patients with Multiple Myeloma

Background: Frailty is a state of decreased reserve affecting multiple organ systems, thereby increasing vulnerability to stressors. Several tools have been proposed to measure frailty in multiple myeloma (MM), such as the IMWG frailty index, and the Revised Myeloma Comorbidity Index. However, these are based on clinical trial datasets, and include chronological age as one of the indicators of frailty. A frailty index based on the principle of accumulation of health deficits (Rockwood doi:10.1093/gerona/62.7.738), provides a measure of physiologic age. This index can be readily calculated using various combinations of health deficits and has been shown to predict outcomes in several populations. Social support has been associated with improved outcomes in various populations, however its impact on survival in patients with MM has not been well studied. The objective of this study was to assess the impact of frailty measured by a deficit accumulation frailty index and the impact of relationship status on outcomes in patients with newly diagnosed MM.

Methods: This is a retrospective study including patients diagnosed with MM between January 6 ^th, 2005, and September 19 ^th, 2018. We calculated a deficit accumulation frailty index using previously published methods (McNallan et. al doi.org/10.1016/j.ahj.2013.07.008, Searle et al. doi.org/10.1186/1471-2318-8-24). We used the electronic medical record system at Mayo Clinic in Rochester, MN, to extract data on activities of daily living (14 items) provided by patient-completed questionnaires, and data on comorbidities as recorded by treating providers (16 items), within 6 months prior to diagnosis. Each item was scored as 0, 0.5, or 1, with 1 indicating the presence of deficit (Table 1). The frailty index was defined as the sum of individual scores divided that by the total number of non-missing items. Patients who had N >2 missing items were excluded. Patients with a frailty index ≥0.15 were considered frail. We also extracted data on self-reported relationship status within 6 months prior to diagnosis. Variables were compared between groups using Fisher's exact test and Wilcoxon signed-rank test for categorical and continuous variables, respectively. Univariate and multivariate analysis were performed using Cox proportional hazard models. Overall survival (OS) was estimated using the Kaplan-Meier method and compared between groups using the Log-rank test. P values <0.05 were considered statistically significant.

Results: We included 578 patients. Median age was 67 (interquartile range: 59-74) years, and 40% were female. Among all patients, 226 (39%) were frail. Compared to fit patients, patients who were frail were older (median age: 70 vs. 65 years, P<0.001) and more likely to have International Staging System (ISS) III (vs. I/II) disease (47% vs. 27%, P<0.001) and ECOG performance status ≥2 (vs. 0 or 1) (45% vs. 17%, P<0.001). There was no difference in R-ISS III disease or presence of high-risk cytogenetic abnormalities between fit and frail patients. Median OS was 7.6 and 4.1 years in fit and frail patient, respectively (P<0.001). Physician assessed ECOG performance status was available for 268 patients. Among patients with ECOG performance status 0 or 1 (193 patients), 136 (70%) were fit, and 57 (30%) were frail. The OS was 8.3 and 4.6 years in the 2 groups, respectively (P=0.006) (table 2). On multivariate analysis including age, frailty status, and R-ISS stage (III vs. I/II), all were associated with OS with frailty's hazard ratio (HR): 1.4 (95%CI [1.1-1.8]), P=0.004; the HR was 1.4 (95%CI [1.1-1.9]), P=0.02, when analysis was restricted to patients ≥60 years. Among all patients, those who were married or in a committed relationship (474 patients) had improved survival (median OS: 7.0 vs. 3.7 years, respectively, P<0.001) compared to patients who were divorced/separated, widowed, or single (96 patients). On multivariate analysis, which included age, R-ISS III, frailty status, and relationship status, all were associated with OS. The HR for relationship status was 1.4 (95%CI [1.0-1.8]), P=0.0465.

Conclusion: Frailty, defined by the deficit accumulation frailty index, is independently associated with decreased survival in patients with newly diagnosed MM. Being married or in a committed relationship is associated with improved survival independent of age, disease stage, and frailty.