Identification of Effective Factors on the Survival of Hemodialysis Patients Using the LASSO-Cox Approach

Abstract

Background: Hemodialysis is a method for removing excess fluid and uremic waste from the body of chronic renal failure (CRF) patients. It stops death in patients with CRF. Various factors can affect the survival of patients undergoing hemodialysis treatment. The current study aimed to determine some factors affecting hemodialysis patients’ survival using the LASSO-Cox approach. Methods: This cross-sectional study examined 252 patients undergoing hemodialysis from 2010 to 2016 in all hospitals of Bandar Abbas, Iran, whose data had been recorded in the hemodialysis unit, or it was possible to obtain their files. The Cox model under the LASSO variable selection technique (LASSO-Cox) was applied for data analysis. The collected data were analyzed using SPSS 23.0 (IBM) software and glmnet and survival packages in R software, version 3.5.1. Results: Overall, 35 (13.9%) death events were observed in this study. The mean follow-up time of 252 patients was equal to 10.93±7.82 years. Based on the results of the Cox-Lasso method, the risk of mortality for patients with a diploma was 49% lower than that of the illiterate group (HR=0.51; 95% CI: 0.02, 0.57; P=0.021). The risk of death for unemployed patients and farmers was 0.66 (HR=1.66; 95% CI: 1.51, 25.79; P=0.004) and 0.29 (HR=1.29; 95% CI: 1.14, 27.40; P=0.005) higher than that of employees, respectively. Further, by an increase in the frequency of dialysis per week, the risk of death was reduced by 0.34 (HR=0.66; 95% CI: 0.04, 0.82; P=0.022), and one unit increase in the duration of dialysis per hour increased the risk of death by 2.23 times (HR=2.23; 95% CI: 1.41, 27.1; P=0.010). Conclusion: Education level, job, frequency of hemodialysis per week, and duration of hemodialysis per hour were the most important variables in the survival of hemodialysis patients. As a result, it seems that more education for nurses working in hemodialysis wards and the involved patients can be useful to heed the recommendations of physicians in terms of the required duration for hemodialysis per hour and the number of sessions per week.