Key result
In patients with HFrEF and iron deficiency, the minimal clinically important difference for a little improvement in the 6-minute walk test was 14 meters at 12 weeks and 15 meters at 24 weeks.
Why the study?
The magnitude of change in the 6MWT that is clinically meaningful for individuals is not well established in HFrEF.
Mean Difference: 14 (95% CI 5–23)
The minimal clinically important difference for improvement in the 6-minute walk test in patients with HFrEF and iron deficiency is 14 to 15 meters, providing a benchmark for interpreting clinical trial data.
Provides benchmark for 6MWT change in iron-deficient HFrEF; extends prior MCID estimates but remains hypothesis-generating pending RCTs.
BACKGROUND: The 6-minute walk test (6MWT) is widely used to measure exercise capacity; however, the magnitude of change that is clinically meaningful for individuals is not well established in heart failure with reduced ejection fraction (HFrEF). OBJECTIVE: To calculate the minimal clinically important difference (MCID) for change in exercise capacity in the 6MWT in iron-deficient populations with HFrEF. METHODS: In this pooled secondary analysis of the FAIR-HF and CONFIRM-HF trials, mean changes in the 6MWT from baseline to weeks 12 and 24 were calculated and calibrated against the Patient Global Assessment (PGA) tool (clinical anchor) to derive MCIDs in improvement and deterioration. RESULTS: Of 760 patients included in the 2 trials, 6MWT and PGA data were available for 680 (89%) and 656 (86%) patients at weeks 12 and 24, respectively. The mean 6MWT distance at baseline was 281 ± 103 meters. There was a modest correlation between changes in 6MWT and PGA from baseline to week 12 (r = 0.31; P < 0.0001) and week 24 (r = 0.43; P < 0.0001). Respective estimates (95% confidence intervals) of MCID in 6MWT at weeks 12 and 24 were 14 meters (5;23) and 15 meters (3;27) for a "little improvement" (vs no change), 20 meters (10;30) and 24 meters (12;36) for moderate improvement vs a "little improvement,", -11 meters (-32;9.2) and -31 meters (-53;-8) for a "little deterioration" (vs no change), and -84 meters (-144;-24) and -69 meters (-118;-20) for "moderate deterioration" vs a "little deterioration". CONCLUSIONS: The MCID for improvement in exercise capacity in the 6MWT was 14 meters-15 meters in patients with HFrEF and iron deficiency. These MCIDs can aid clinical interpretation of study data.
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Khan et al. (2022) studied Heart failure with reduced ejection fraction (HFrEF) and iron deficiency (n=760). Change in 6-minute walk test (6MWT) distance vs. No change in Patient Global Assessment (PGA) was evaluated on Minimal clinically important difference (MCID) for 'little improvement' (vs no change) in 6MWT at week 12 (14 meters, 95% CI 5;23). In patients with HFrEF and iron deficiency, the minimal clinically important difference for a little improvement in the 6-minute walk test was 14 meters at 12 weeks and 15 meters at 24 weeks.
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