MO673: Association of Mean Corpuscular Volume with Mortality in Kidney Failure Patients: Opposite Findings in Chinese and Swedish Kidney Failure Patients

Abstract

Abstract BACKGROUND AND AIMS Higher mean corpuscular volume (MCV), a measure of the average size of the circulating erythrocyte used for differential diagnosis of anemia or for monitoring macrocytosis, is associated with higher mortality in various clinical settings including in patients (pts) with kidney failure; however, results are not consistent and a study from Japan (Honda et al. Low rather than high mean corpuscular volume is associated with mortality in Japanese patients under hemodialysis. Sci Rep. 2020; 10(1): 15 663) found that low MCV associated with mortality in 8571 hemodialysis pts (mean age 62.5 ± 12.7 years, 37.2% female, median MCV 96.1 fL) pts. We investigated the relationship between MCV with all-cause and cardiovascular mortality in two cohorts of kidney failure pts from China and Sweden. METHOD In 731 incident Chinese peritoneal dialysis pts (median age 50 years, 57% males) and 404 Swedish kidney failure pts (median age 56 years, 62% males), baseline MCV and other biochemical and metabolic biomarkers were analysed in relation to mortality during follow-up period of up to 5 years. All-cause and cardiovascular disease (CVD) mortality risk were analysed with competing-risk regression models with transplantation as competing risk adjusting for age, sex, smoking, diabetes, serum albumin, hemoglobulin and calendar year. RESULTS Chinese pts were significantly younger (P < 0.01) and had lower body mass index (P < 0.01) and Framingham risk score (P < 0.01) than Swedish pts while gender distribution was similar. In univariate analysis, MCV was associated with body mass index (P < 0.01) and mean arterial blood pressure (P < 0.01) in both cohorts. ‘Chinese pts’: During median 3.6 years of follow-up, all-cause mortality rate was 16%, and 52 (46%) of 111 deaths were caused by CVD. Low MCV (<94 fL) was associated with significantly higher all-cause [Fig. 1A; sub-hazard ratio, sHR (95% CI) 2.15 (1.14–4.06)] but not CVD mortality (Fig. 2A) when adjusting for all confounders. ‘Swedish pts’: During median 2.1 years of follow-up, all-cause mortality rate was 30%, and 53 (44%) of the 120 deaths were caused by CVD. In contrast to the Chinese cohort, pts low MCV (<94 fL) was associated with lower both all-cause [Fig. 1B; sHR 0.62 (0.39–0.97)] and CVD mortality [Fig. 2B; sHR 0.49 (0.26–0.94)] when adjusting for all confounders. CONCLUSION In Chinese kidney failure pts low MCV was associated with higher all-cause mortality risk while in Swedish kidney failure pts low MCV was associated with pts lower all-cause and CVD mortality risk, independently of all confounders. Further studies are needed to explore if this difference may reflect regional differences in factors affecting MCV.