Physical strain of walking in patients with PPS.

BACKGROUND:

Survivors of poliomyelitis may develop new neuromuscular symptoms later on in life, including new muscle weakness, fatigue and muscle pain. These new symptoms are referred to as the postpoliomyelitis syndrome (PPS). PPS may cause increasing difficulties with mobility, by a reduced walking speed and an increased physical strain of walking, which can be up to 3 times higher, compared to healthy controls. In the literature, two distinct walking capacity tests are commonly used to assess the physical strain of walking, including the 6-minute walk test (6MWT) and the energy cost of walking test (ECWT). However, the reproducibility of both these tests in PPS patients has never been compared.



OBJECTIVES:

To determine the reproducibility of the ECWT and the 6MWT for assessing the physical strain of walking in patients with PPS and in healthy control subjects; to evaluate the one-year course of the physical strain of walking among patients with PPS and healthy control subjects, as quantified with the ECWT and the 6MWT.



STUDY DESIGN:

An intra-rater (i.e. between occasions) test-retest reproducibility study will be conducted at the outpatient clinic of the department of Rehabilitation in the Academic Medical Center in Amsterdam.



STUDY POPULATION:

Forty patients with PPS (age 18-75 years) who are capable of walking independently for more than 150m without any supportive devices are eligible, as well as 40 age-matched healthy controls.



STUDY PARAMETERS:

The primary study parameters are speed (in m/min), 6-minute walking distance (6MWD in m), heart rate (HR in b/min), and EC walking (in J/kg/m), as measured with the ECWT. From the 6MWT speed, 6MWD, and HR will be calculated. Secondary study parameters are the patient’s perceived exertion score (as measured with the Borg scale), and the patient’s perceived fatigue score (as measured with the CISr20, the fatigue severity scale (FSS), and the Dutch Exertion Fatigue Scale (DEFS)).



Measurements with the ECWT and the 6MWT will be performed three times within one year (at T1 = 0 weeks (test), at T2 = 2 weeks (retest) and at T3 = 12 months (1-year follow-up)). The duration of these tests will be approximately 45 minutes. Furthermore, at the first visit the patient is asked to fill in three fatigue questionnaires (CISr20, FSS and DEFS). The duration for completing these questionnaires is 10 minutes.



STATISTICAL ANALYSIS:

This will include descriptive and correlation statistics for all measurements; reproducibility statistics based on the T1 and T2 measurements; and paired samples t-tests between the mean of measurements at T1 and T2 and measurements at T3.

1. To determine the reproducibility of the energy cost of walking test (ECWT) and the 6-minute walk test (6MWT) for assessing the physical strain of walking in patients with postpoliomyelitis syndrome (PPS) and in healthy control subjects;

2. To evaluate the one-year course of the physical strain of walking among patients with PPS and healthy control subjects, as quantified with the ECWT and the 6MWT;

3. To determine the relationship between the physical strain of walking and perceived fatigue in patients with PPS.

1. May 2012 – May 2014: Recruitment of participants and baseline measurements (T1);

2. May 2012 – July 2014: Follow up measurements (T2-T3);

3. May 2012 – July 2014: Data-analysis;

4. May 2014 – December 2014: Statistical analysis;

5. November 2014 – May 2015: Writing of scientific articles.

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