BACKGROUND: Iron deficiency (ID) is a common condition in non-dialysis dependent chronic kidney disease (NDD-CKD) patients that is associated with poorer clinical outcomes. However, the effect of ID on health-related quality of life (HRQoL) in this population is unknown. We analyzed data from a multinational cohort of NDD-CKD stage 3 to 5 patients to test the association between transferrin saturation index (TSAT) and ferritin with HRQoL. METHODS: Patients from Brazil (N = 205), France (N = 2015), and the US (N = 293) in the CKD Outcomes and Practice Patterns Study (CKDopps, 2013 to 2019) were included. We evaluated the association of TSAT and ferritin (and functional and absolute ID, defined as TSAT ≤ 20% and ferritin >300 or < 50 ng/mL, respectively) on pre-specified HRQoL measures, including KDQOL-36 PCS and MCS as the primary outcomes. Models were adjusted for confounders including hemoglobin (Hgb). RESULTS: TSAT ≤15% and both ferritin <50 ng/mL and ≥300 ng/mL were associated with worse PCS scores, but not with MCS. Patients with composite TSAT ≤20% and ferritin <50 or ≥ 300 ng/mL had lower functional status and worse PCS than those with TSAT of 20%-30% and ferritin 50-299 ng/mL. Patients with lower TSAT were less likely to perform intense physical activity. Adjustment for Hgb only slightly attenuated the observed effects. CONCLUSIONS: Low TSAT levels, as well as both low TSAT with lower ferritin and low TSAT with high ferritin, are associated with worse physical HRQoL in NDD-CKD patients, even after accounting for Hgb level. Interventional studies of iron therapy on HRQoL among NDD-CKD individuals are needed to confirm these findings.
BACKGROUND:Iron deficiency (ID) is a common condition in non-dialysis dependent chronic kidney disease (NDD-CKD) patients that is associated with poorer clinical outcomes. However, the effect of ID on health-related quality of life (HRQoL) in this population is unknown. We analyzed data from a multinational cohort of NDD-CKD stage 3 to 5 patients to test the association between transferrin saturation index (TSAT) and ferritin with HRQoL. METHODS:Patients from Brazil (N = 205), France (N = 2015), and the US (N = 293) in the CKD Outcomes and Practice Patterns Study (CKDopps, 2013 to 2019) were included. We evaluated the association of TSAT and ferritin (and functional and absolute ID, defined as TSAT ≤ 20% and ferritin >300 or < 50 ng/mL, respectively) on pre-specified HRQoL measures, including KDQOL-36 PCS and MCS as the primary outcomes. Models were adjusted for confounders including hemoglobin (Hgb). RESULTS: TSAT ≤15% and both ferritin <50 ng/mL and ≥300 ng/mL were associated with worse PCS scores, but not with MCS. Patients with composite TSAT ≤20% and ferritin <50 or ≥ 300 ng/mL had lower functional status and worse PCS than those with TSAT of 20%-30% and ferritin 50-299 ng/mL. Patients with lower TSAT were less likely to perform intense physical activity. Adjustment for Hgb only slightly attenuated the observed effects. CONCLUSIONS: Low TSAT levels, as well as both low TSAT with lower ferritin and low TSAT with high ferritin, are associated with worse physical HRQoL in NDD-CKDpatients, even after accounting for Hgb level. Interventional studies of iron therapy on HRQoL among NDD-CKD individuals are needed to confirm these findings.