Competing risk analysis of cardiovascular mortality in multiple myeloma survivors

Abstract

Background The survival of multiple myeloma (MM) patients has significantly improved, and several factors increase the risk of cardiovascular death (CVD) mortality in MM. This study aims to determine the prognostic significance of factors associated with long-term CVD risk in MM survivors. Methods The data of MM survivors whose survival time was longer than 36 months were retrieved from the Surveillance, Epidemiology, and End Result (SEER) database between 2000 and 2015. Cox proportional hazards regressions and competing risk survival analyses were utilized to assess the CVD-associated risk factors. Propensity score matching (PSM) was further conducted to ensure the comparability of cardiovascular risk factors. The nomogram was based on these epidemiological factors to estimate individualized CVD probabilities for MM survivors, and its performance was assessed by Harrell’s concordance index (C-index) and calibration curve. Results A total of 32,528 survivors with MM were enrolled, and 2,061 (6.34%) suffered from CVD. In Cox proportional hazards regressions and competing risk survival analyses, age, period of diagnosis, sex, race, married status, income, chemotherapy, and radiotherapy were the independent risk factors for CVD. After PSM, there was a significant difference in cumulative incidence curves, using a competing-risks method, between the following matched groups: male vs. female group, white vs. non-white group, married vs. unmarried group, income <$75,000 vs. income ≥$75,000 group, chemotherapy vs. non-chemotherapy group, and radiotherapy vs. non-radiotherapy group. The nomogram predicted CVD probabilities with a training C-index of 0.700 and a validation C-index of 0.726. Calibration curves validated that the nomograms could accurately predict the CVD probabilities both in the training and validation group. Conclusions Among MM survivors, the mortality risk of cardiovascular diseases differs with age, sex, period at diagnosis, race/ethnicity, marital status, chemotherapy, and radiotherapy. Our nomograms, based on epidemiological variables, may be used to predict 5-, 10-, and 15-year cardiovascular disease outcomes of MM survivors.