Comparing 6-Minute Walk Tests for Ambulatory Oxygen Assessment V1

  • Research type

    Research Study

  • Full title

    Comparison of the standard Maximal 6-Minute Walk Test against a Normal-speed 6-Minute Walk Test as an alternative and accurate assessment for ambulatory oxygen requirement

  • IRAS ID

    306758

  • Contact name

    Harry Griffin

  • Contact email

    harry.griffin@hhft.nhs.uk

  • Clinicaltrials.gov Identifier

    NCT05630092

  • Duration of Study in the UK

    1 years, 9 months, 24 days

  • Research summary

    Patients with lung disease who report breathlessness on exertion are often referred for a 6MWT. During this test patients are asked to walk up and down a corridor (or other flat area) for six minutes whilst their blood oxygen levels and heart rate are non-invasively measured using a pulse oximeter (finger probe) and the distance walked is measured. In addition, a questionnaire that obtains a Borg Score measures the patients perceived breathlessness and leg muscle fatigue both before and immediately following the test.

    Due to the nature of the 6MWT (hereon referred to as a Max-6MWT), patients are required to walk as far as they can in 6 minutes. This may lead to an inaccurate assessment of their requirement for ambulatory oxygen as this form of exercise may not correspond to their normal daily activities. It may also not accurately measure the normal changes in oxygen saturation (or desaturation) that occurs in these patients during their normal daily activities (such as walking to the shops, walking up the stairs, gardening).

    In this study, patients who are routinely referred for a Max-6MWT to investigate possible exercise-induced hypoxaemia will be invited to perform an additional walking test which is performed at their normal walking speed, referred here on in as a Nor_6MWT. We hypothesise that performing a Nor_6MWT will provide a more accurate assessment of a patients' oxygen requirement, primarily from their oxygen desaturation during the test.

    Summary of study results:

    The 6-minute walk test is a test whereby a patient is instructed to walk as far as they can in 6 minutes on a flat level surface, usually a corridor 30 meters in length. In clinical practice, it is usually used to determine if patients will benefit from ambulatory oxygen – a portable oxygen source to help improve the distance they can walk and reduce breathlessness during daily activities. However, asking patients to walk as far as possible in 6 minutes (maximal effort test) may not be the most accurate way to assess if they will have any benefit from ambulatory oxygen during their normal day-to-day activities such as walking a dog or walking to the shops. Furthermore, the 6-minute walk test was never originally designed as a clinical assessment for ambulatory oxygen.

    We propose to modify the way the test is performed from the international guidelines that instruct patients to “walk as far as you can” and ask patients to instead perform the test at their normal walking speed, similar to that if they were walking to the shops or walking a dog. The aim was to identify if this modification alters the information provided by the 6-minute walk test and if this can better predict patients that require and go on to benefit from ambulatory oxygen.

    Summary of study results:
    A total of 82 participants were included in the final data analysis. Of these, 45 were randomised to Group 1 and 37 to Group 2 - these two groups were treated identically other than Group 1 performed the maximal test first followed by walking at their normal pace, and Group 2 in the opposite order.
    The mean age of participants was 69.36 in Group 1 and 68.24 in Group 2. The sex split was 17:28 (F:M) and 10:27 (F:M) in each group respectively. There was no statistical difference between the demographics of each group, suggesting they are well matched.

    Overall, there were differences between the two tests, with participants walking a shorter distance (an average [mean] difference of 68m less in the normal speed test) and having a smaller drop in their oxygen levels (an average [mean] of 0.5% smaller on the normal speed test) when walking at their normal walking speed compared to walking as far as possible. In addition, a lower peak heart rate (an average [median] of 7.5bpm lower) in the normal speed test. Whilst these differences are small, importantly, 16% of participants could have been offered ambulatory oxygen on the test following international guidelines (maximal effort test) but would not be offered it if performing the test at their normal walking pace.

    Unfortunately, due to the small numbers proceeding ambulatory oxygen therapy, we were unable to answer the follow up question as to which walk test may best predict the benefit of this therapy.

    The research team are hoping to publish the full dataset as a publication in a peer reviewed journal. We would like to thank all study participants for their involvement, including the clinical and research team involved in the data collection and processing.

  • REC name

    South Central - Hampshire B Research Ethics Committee

  • REC reference

    22/SC/0399

  • Date of REC Opinion

    30 Nov 2022

  • REC opinion

    Further Information Favourable Opinion