Assessment of daily life physical activities in pulmonary arterial hypertension

Abstract

Background: In pulmonary arterial hypertension (PAH), the six-minute walk test (6MWT) is believed to be representative of patient's daily life physical activities (DL(PA)). Whether DL(PA) are decreased in PAH and whether the 6MWT is representative of patient's DL(PA) remain unknown.

Methods: 15 patients with idiopathic PAH (IPAH) and 10 patients with PAH associated with limited systemic sclerosis (PAH-SSc) were matched with 15 healthy control subjects and 10 patients with limited systemic sclerosis without PAH. Each subject completed a 6MWT. The mean number of daily steps and the mean energy expenditure and duration of physical activities >3 METs were assessed with a physical activity monitor for seven consecutive days and used as markers of DL(PA).

Results: The mean number of daily steps and the mean daily energy expenditure and duration of physical activities >3 METs were all reduced in PAH patients compared to their controls (all p<0.05). The mean number of daily steps correlated with the 6MWT distance for both IPAH and PAH-SSc patients (r = 0.76, p<0.01 and r = 0.85, p<0.01), respectively.

Conclusion: DL(PA) are decreased in PAH and correlate with the 6MWT distance. Functional exercise capacity may thus be a useful surrogate of DL(PA) in PAH.

Figure 1. Daily life physical activities in pulmonary arterial hypertension patients and control groups.

Mean number of daily steps (panel A), mean daily energy expended during physical activities inducing a metabolic demand >3 METs (panel B), and mean daily duration of physical activities inducing a metabolic demand >3 METs. (panel C) in healthy control subjects (CTRL; dark bars), patients with idiopathic pulmonary arterial hypertension (IPAH; grey bars), patients with limited systemic sclerosis without PAH (SSc; hatched bars), and patients with pulmonary arterial hypertension associated with limited systemic sclerosis (PAH-SSc; open bars). Values are mean ± SD. * p<0.01 vs. CTRL; § p≤0.01 vs. SSc; # p = 0.02 vs SSc. Figure legend: kcal, kilocalories; n, number.

Figure 2. Correlation between exercise capacity and daily steps in pulmonary arterial hypertension patients.

Correlation between the six-minute walk test (6MWT) distance and the mean daily steps in patients with idiopathic pulmonary arterial hypertension (IPAH; panel A) and in patients with pulmonary arterial hypertension associated with limited systemic sclerosis (PAH-SSc; panel B). Figure legend: n, number; min, minute.

Figure 3. Relation between daily life physical activities and exercise capacity with the New York Heart Association functional class.

Mean number of daily steps (panel A), mean daily energy expended during physical activities inducing a metabolic demand >3 METs (panel B), mean daily duration of physical activities inducing a metabolic demand >3 METs (panel C), and six-minute walk test (6MWT) distance (panel D) in healthy control subjects (CTRL; open bars) and in patients with pulmonary arterial hypertension in New York Heart Association (NYHA) functional class II (dark bars) and III (grey bars). Values are mean (SD). * p<0.05 and † p<.001 vs. CTRL; ‡ p<0.001 vs NYHA II. Figure legend: n, number; kcal, kilocalories; min, minute; m; meter.