Aim To describe and compare the repeatability and responsiveness of the Incremental Shuttle Walk Test (ISWT) and incremental cardiopulmonary exercise test between COPD and Chronic Heart Failure (CHF).
Hypothesis The null hypothesis, no difference in the measurement properties of ISWT and ICE between two chronic diseases.
Methods Patients with symptomatic COPD and CHF (MRC 2 or NHYA II and above, respectively) were recruited. All patients underwent seven weeks of PR (1). At baseline, participants performed a familiarisation ISWT, two ISWTs and two incremental, symptom-limited, cardiopulmonary exercise tests on a cycle ergometer (ICE) within two weeks, on separate days. Both tests were repeated after seven weeks of PR.
Results 55 patients with COPD (70% male, mean [SD] age 73  yr, FEV1 %predicted 43 , FEV1/FVC 50 ) and 44 patients with CHF (66% male, age 71  yr, LVEF 33 %) were recruited.
There was a significant increase mean [SE] of 20  m between the familiarisation ISWT and ISWT1 (p < 0.001). There was no difference between either, ISWT1 and ISWT2, 2 (4) m (p = 0.10), or peak oxygen uptake (VO2pk) for ICE1 and ICE2, 20  ml·min-1 (p = 0.16). There was no effect of disease, p = 0.11 and p = 0.47, respectively. Figure 1 shows the repeatability for the ISWT and ICEVO2pk in both conditions.
Mean [95%CI] change in ISWT after PR was 68 [50–95] m, effect size (ES) 0.58 (p < 0.001) and 62 [35–89] m, effect size 0.57 (p < 0.001), in COPD and CHF, respectively. Mean change in ICEVO2pk was 28 (-14 to 69) ml·min-1, ES 0.09 (p = 0.19) and 50 (-15 to 120) ml·min-1, ES 0.16 (p = 0.12). There was no difference in responsiveness, between COPD and CHF, for the ISWT and ICEVO2pk, p = 0.44 and p = 0.67, respectively.
Conclusions Both the ISWT and ICE are similarly repeatable in patients with COPD and CHF. A 60 m change in ISWT distance and 260mls in ICEVO2pk represents, with 95% certainty, a true change within an individual. ICEVO2pk wassimilarly unresponsive to PR in both conditions.
Evans RA et al. Respir Med 2010; 104(10):1473–1481.
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