Six-minute walk test may be a reliable predictor of peak oxygen uptake in patients undergoing hemodialysis

Background

Cardiorespiratory fitness seems to play an important role in the general health of patients undergoing hemodialysis (HD). However, the prediction of peak oxygen uptake (V̇O2peak) in a clinical setting is not widely adopted for these patients.

Objectives

Evaluate the agreement and reliability between directly and indirectly V̇O2peak measurements in patients undergoing HD.

Methods

This is a cross-sectional study with patients undergoing HD that performed a cardiopulmonary exercise test (CPET) with 5/10 watts incremental load in each minute using a cycle ergometry to directly evaluate the V̇O2peak, and the 6-min walk test (6MWT) in a 30-m corridor to indirect measures it. Both tests were performed on a midweek non-dialysis day. Bland–Altman analysis of agreement limits was used with direct and indirect V̇O2peak values. Intraclass correlation coefficient (ICC) and Cronbach’s Alpha was used to evaluate the reproducibility and reliability between direct and indirect V̇O2peak values.

Results

Twenty-six patients (54.4 ± 14.5 years, 53.8% of male) were evaluated. The V̇O2peak direct mean obtained through CPET was 15.91 ± 5.26 (ml/kg/min), while the indirect mean obtained through 6MWT was V̇O2peak of 14.89 ± 4.21 (ml/kg/min). There was a strong positive correlation between both V̇O2peak values (r = 0.734; p < 0.001). The Bland–Altman analysis demonstrated that the methods agreed with each other (p = 0.103). Also, the ICC (0.829) and Cronbach's Alpha (0.846) showed excellent reproducibility and reliability.

Conclusions

6MWT is a reliable tool for estimating V̇O2peak in patients undergoing HD.

Dyspnoea-12 and Multidimensional Dyspnea Profile: Systematic Review of Use and Properties

CONTEXT

The Dyspnoea-12 (D-12) and Multidimensional Dyspnea Profile (MDP) were specifically developed for assessment of multiple sensations of breathlessness.

OBJECTIVES

This systematic review aimed to identify the use and measurement properties of the D-12 and MDP across populations, settings and languages.

METHODS

Electronic databases were searched for primary studies (2008-2020) reporting use of the D-12 or MDP in adults. Two independent reviewers completed screening and data extraction. Study and participant characteristics, instrument use, reported scores and minimal clinical important differences (MCID) were evaluated. Data on internal consistency (Cronbach's α) and test-retest reliability (intraclass correlation coefficient, ICC) were pooled using random effects models between settings and languages.

RESULTS

A total 75 publications reported use of D-12 (n = 35), MDP (n = 37) or both (n = 3), reflecting 16 chronic conditions. Synthesis confirmed two factor structure, internal consistency (Cronbach's α mean, 95% CI: D-12 Total = 0.93, 0.91-0.94; MDP Immediate Perception [IP] = 0.88, 0.85-0.90; MDP Emotional Response [ER] = 0.86, 0.82-0.89) and 14 day test-rest reliability (ICC: D-12 Total = 0.91, 0.88-0.94; MDP IP = 0.85, 0.70-0.93; MDP ER = 0.84, 0.73-0.90) across settings and languages. MCID estimates for clinical interventions ranged between -3 and -6 points (D-12 Total) with small variability in scores over 2 weeks (D-12 Total 2.8 (95% CI: 2.0 to 3.7), MDP-A1 0.8 (0.6 to 1.1) and six months (D-12 Total 2.9 (2.0 to 3.7), MDP-A1 0.8 (0.6 to 1.1)).

CONCLUSION

D-12 and MDP are widely used, reliable, valid and responsive across various chronic conditions, settings and languages, and could be considered standard instruments for measuring dimensions of breathlessness in international trials.