Association of estimated glomerular filtration rate with all-cause and cardiovascular mortality: The role of malnutrition-inflammation-cachexia syndrome

Background: Previous studies have demonstrated that high estimated glomerular filtration rate (eGFR) is paradoxically associated with an increased risk of mortality, and the association becomes more predominant in older people. However, the role of malnutrition-inflammation-cachexia syndrome (MICS) in the association between eGFR and mortality has never been explored. Methods: We conducted a community-based cohort study using data from the Taipei City Elderly Health Examination Database, collected during the period 2001-10. All participants aged ≥65years were included and stratified by the absence or presence of MICS, which is defined as the presence of at least one of the following markers: body mass index <22kg/m², serum albumin <3.0mg/dL, or Geriatric Nutritional Risk Index (GNRI) <98. The study endpoints were all-cause and cardiovascular mortality. Results: A total of 131354 participants were identified and categorized according to the chronic kidney disease stage based on eGFR. Compared with the reference eGFR of 60-89mL/min/1.73m², the overall and cardiovascular mortality risks were markedly high in the groups with eGFR of <30mL/min/1.73m² [overall: adjusted hazard ratio (aHR), 1.86; 95% confidence interval (CI), 1.72-2.00; cardiovascular: aHR, 1.87; 95% CI, 1.60-2.19] and ≥90mL/min/1.73m² (overall: aHR, 1.23; 95% CI, 1.13-1.34; cardiovascular: aHR, 1.28; 95% CI, 1.06-1.54). In the absence of MICS, high eGFR was associated with lower mortality risk (aHR, 0.71; 95% CI, 0.62-0.80), and the U-shaped relationship disappeared. Subgroup analyses produced consistent results. Conclusions: MICS could influence the association observed between high eGFR and mortality in older people, particularly in those with low body mass index, albumin level, GNRI, and very low serum creatinine level.