Associations of Hemoglobin Levels With Health-Related Quality of Life, Physical Activity, and Clinical Outcomes in Persons With Stage 3-5 Nondialysis CKD

Objective: Conflicting findings and knowledge gaps exist regarding links between anemia, physical activity, health-related quality of life (HRQOL), chronic kidney disease (CKD) progression, and mortality in moderate-to-advanced CKD. Using the CKD Outcomes and Practice Patterns Study, we report associations of hemoglobin (Hgb) with HRQOL and physical activity, and associations of Hgb and physical activity with CKD progression and mortality in stage 3-5 nondialysis (ND)-CKD patients.

Design and methods: Prospectively collected data were analyzed from 2,121 ND-CKD stage 3-5 patients, aged ≥18 years, at 43 nephrologist-run US and Brazil CKD Outcomes and Practice Patterns Study-participating clinics. Cross-sectional associations were assessed of Hgb levels with HRQOL and physical activity levels (from validated Kidney Disease Quality of Life Instrument and Rapid Assessment of Physical Activity surveys). CKD progression (first of ≥40% estimated glomerular filtration rate [eGFR] decline, eGFR<10 mL/min/1.73 m², or end-stage kidney disease) and all-cause mortality with Hgb and physical activity levels were also evaluated. Linear, logistic, and Cox regression analyses were adjusted for country, demographics, smoking, eGFR, serum albumin, very high proteinuria, and 13 comorbidities.

Results: HRQOL was worse, with severe anemia (Hgb<10 g/dL), but also evident for mild/moderate anemia (Hgb 10-12 g/dL), relative to Hgb>12 g/dL. Odds of being highly physically active were substantially greater at Hgb>10.5 g/dL. Lower Hgb was strongly associated with greater CKD progression and mortality, even after extensive adjustment. Physical inactivity was strongly associated with greater mortality and weakly associated with CKD progression. Possible residual confounding is a limitation.

Conclusion: This multicenter international study provides real-world observational evidence for greater HRQOL, physical activity, lower CKD progression, and greater survival in ND-CKD patients with Hgb levels >12 g/dL, exceeding current treatment guideline recommendations. These findings help inform future studies aimed at understanding the impact of new anemia therapies and physical activity regimens on improving particular dimensions of ND-CKD patient well-being and clinical outcomes.