6MWT does not reflect activity in primary care COPD patients

Researchers have found that functional exercise capacity does not reflect physical activity among chronic obstructive pulmonary disease (COPD) patients treated in primary care.

In a study of 51 patients, there was no significant correlation between achievement in the 6-minute walk test (6MWT) and actual daily activity, such as the number of steps taken or total active time.

Authors Annemieke Fastenau (Maastricht University Medical Centre, the Netherlands) and colleagues say the findings suggest that primary care physicians should tailor the treatment of COPD patients to adjust the balance between trying to increase exercise capacity and daily physical activity.

“These results reinforce the importance of measuring daily physical activity in order to fine-tune treatment,” they comment.

Their study included primary care-treated COPD patients with mild–moderate disease (mean forced expiratory volume in 1 second [FEV1], 74% predicted).

Overall, 6MWT values were similar to those expected for healthy individuals (mean, 487 m). But measurement over 3 days and nights with an accelerometer showed that patients had a mean physical activity level (PAL) of 1.45, where a PAL of 1.40–1.69 defines a predominantly sedentary person. And patients achieved on average only 65% of the recommended 10,000 steps per day.

There was no significant correlation between distance achieved in the 6MWT and any of the physical activity variables, including steps per day, movement intensity during walking, time spent walking per day, total active time, time in moderate physical activity, time in vigorous activity level, and PAL. For example, among those with normal functional exercise capacity, the number of steps walked per day ranged from 3000 to 15,000.

Writing in the Primary Care Respiratory Journal, Fastenau and colleagues say that the study “reinforces the idea that, although FEV1, [Medical Research Council] dyspnoea scale and even functional exercise capacity might be important outcomes to indicate the severity of the disease… daily physical activity provides a supplementary concept, especially in patients with mild to moderate COPD.”

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