Exploring the association between quality of life and survival in patients with transthyretin amyloidosis
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BACKGROUND: Studies in various chronic diseases have correlated health-related quality of life (HRQOL) with disease state and treatment outcomes. Limited data exists on the association between HRQOL, survival, and clinical biomarkers of disease in wild-type and familial TTR amyloidosis (ATTRwt & ATTRm) patient populations. OBJECTIVES: To assess the association between HRQOL and survival, as well as HRQOL and clinical biomarkers of disease in transthyretin-mediated amyloidosis (ATTR) patient populations. METHODS: Using a retrospective cohort study design, HRQOL was assessed via SF-36 health surveys collected from patients with ATTRwt and ATTRm presenting for their initial evaluation at the BU Amyloidosis Center between 1985 and 2015. Kaplan-Meier curves and hazard ratios (HRs) calculated using Cox proportional hazards regression analysis were used to examine the association between physical (PCS) and mental (MCS) component scores derived from the SF-36 health surveys and survival follow-up. All analyses were adjusted for potential confounders such as age at presentation, gender, and co-morbidities including diabetes mellitus, hypertension and hyperlipidemia. Spearman’s rank correlations were calculated to assess the association between PCS, MCS and clinical biomarkers of disease (mBMI, troponin I and BNP) also collected at time of initial evaluation visit. Statistical significance was set at a two-sided alpha=0.05. RESULTS: In the ATTRwt cohort, 133 white males, aged 74.6 +/- 6.0 years (mean + SD) presented with mean MCS (45.7 +/- 12.3) and PCS (36.7 +/- 10.8) that were respectively, 0.5 and 1.5 SD below 50. Patients with PCS or MCS scores < 35 had a significantly higher risk of death during follow-up than those with scores >= 35 for PCS (HR=2.45; p=0.002) and for MCS (HR=3.38, p<0.0001). BNP and troponin I associated with MCS (r= - 0.24; p=0.01 and p=0.02, respectively) and PCS (r= - 0.29; p=0.002 and r= - 0.25; p=0.012, respectively). In the ATTRm cohort, 331 white (82%) males (67%), aged 57.5 +/- 13.9 years presented with mean MCS (45.2 +/- 11.7) and PCS (37.2 +/- 13.3). Patients with PCS scores < 35 had a significantly higher risk of death during follow-up than those with scores >= 35 (HR=2.76; p= <0.0001). In contrast, MCS scores < 35 did not correlate with increased risk of death during follow-up (HR=1.38, p=0.13). BNP and troponin I most strongly associated with PCS (r= - 0.50; p<0.0001 and r= - 0.41; p<0.0001, respectively) and less with MCS (r= - 0.16; p=0.03 and r= - 0.24; p=0.007, respectively). mBMI did not associate with MCS or PCS in the ATTRwt and ATTRm cohorts. CONCLUSIONS: ATTR disease significantly decreased an individual’s physical and mental HRQOL. PCS and MCS were shown to be independent predictors of mortality but their ability to predict survival varied by cohort. Assessment of HRQOL may provide valuable prognostic information that could be of use in the management of ATTR disease.