Self-Reported Quality of Life for Predicting Mortality in Renal Cell Carcinoma
Quality of life (QOL) in cancer patients has gained increasing attention and may provide prognostic value above and beyond traditional demographic and disease parameters. We evaluate the utility of self-reported QOL to predict mortality in patients with renal cell carcinoma (RCC).
The Medicare Health Outcomes Survey was linked to the SEER database to identify patients who completed a QOL questionnaire after the diagnosis of RCC from 1998-2014. Mental component summary (MCS) and physical component summary (PCS) scores were classified as high (≥50) or low (<50) based on a population mean score of 50 points. Patients were classified into four groups: 1) high MCS, high PCS; 2) high MCS, low PCS; 3) low MCS, high PCS; and 4) low MCS, low PCS. Multivariable Cox proportional hazards regression evaluated associations between QOL and all-cause mortality (ACM). The Harrell's concordance statistic (C-index) estimated the model's predictive accuracy. Fine and Gray competing risks models adjusting for disease extent, demographics, and comorbidities evaluated the incidence of RCC-specific and non-RCC-specific mortality.</p>
A total of 1494 patients with a median age of 73.4 years (IQR 68.8-79.3) at survey completion were included. Median follow-up was 5.6 years (IQR 4.0-8.3). There were 747 deaths, of which 139 were due to RCC. Cox regression showed that each additional MCS and PCS point reduced the hazard of ACM by 1.3% (95% CI 0.981-0.993, P<0.001) and 2.2% (95% CI 0.972-0.985, <I>P<0.001), respectively. The C-index was 72.1%. In the competing risks model, the subdistribution hazard ratio (SHR) of RCC mortality in Groups 2, 3, and 4 were 2.71 (95% CI 1.18-6.22, <I>P=0.02), 4.55 (95% CI 1.57-13.18, P=0.005), and 3.11 (95% CI 1.35-7.16, P=0.008), respectively, compared to Group 1 [Figure A]. The SHR for non-RCC mortality in Groups 2, 3, and 4 were 1.50 (95% CI 1.16-1.94, P=0.002), 1.03 (95% CI 0.59-1.78, P=0.9), and 1.83 (95% CI 1.41-2.38, P<0.001), respectively, relative to Group 1 <B>[Figure B].
Self-reported QOL metrics can be used to predict ACM in RCC patients with good accuracy. Lower PCS and MCS scores led to higher rates of ACM, even after accounting for differences in disease, demographics, and comorbidity. Furthermore, non-RCC mortality was associated more with low physical health rather than low mental health.