Adonis A1, Taylor GP2,3, Alexander CM4
1Imperial College Healthcare NHS Trust, National Centre for Human Retrovirology, London, United Kingdom, 2Imperial College, Medicine, London, United Kingdom, 3Imperial College Healthcare NHS TrustLondon, National Centre for Human Retrovirology, London, United Kingdom, 4Imperial College Healthcare NHS Trust, London, United Kingdom
Background: Detecting early, evolving change and responses to treatment are important clinically in HTLV-1-Associated Myelopathy (HAM). Loss of muscle strength is an early sign of onset or worsening HAM. Manual muscle testing (MMT)to test muscle strength has low reliability. A Hand Held Dynamometer (HHD) can be more accurate than MMT. In other neurological conditions HHD's reliability ranges from good to excellent. However, the reliability and minimal detectable change (MDC) in people with HAM is unknown.
Purpose: The purpose of this study is to test a HHD for reliability and acceptability in patients with HTLV infection.
Methods: At the National Centre for Human Retrovirology, 30 patients with HAM (pwHAM) and 22 asymptomatic carriers (AC's) were recruited during routine clinic visits. The study was conducted twice, 4 weeks apart. Participants were randomised to being tested before or after their walking assessments. Standardised testing procedures included 3 tests per muscle group with 10 seconds rest in-between each test. The muscle groups tested were hip flexors/extensors; knee flexors/extensors, ankle plantar/dorsiflexors. Pain scores using a 10cm visual analogue scale, were documented before and after testing.A patient experience measure was completed before and after testing at both sessions.
Analysis: Reliability is reported using the intra-class correlation coefficients(ICC) and its 95% confidence interval and the MDC is calculated as SEM x 1.96 x √2 where SEM =SDx√1-ICC
Results: 52 participants were included in the study: 30 pwHAM and 22 AC's.
Mean age was 59.5 years in pwHAM compared to 51.5 years in AC's.
Median testing times were similar at baseline and follow up: for pwHAM was 18 minutes compared to 15 minutes in AC's.
Reliability, measured by the Intraclass Correlation Coefficient, was excellent for all lower limb muscle groups tested in pwHAM (ICC=0.84-0.95) & AC's (ICC= 0.82-0.95).
The minimal detectable change for pwHAM ranged from 13.3 Newtons- 25.3 Newtons(24.8%-62.1%) compared to AC's 18.6Newtons-29.4Newtons(13.6%-21.6%).
Feasibility of testing positions:2/30 pwHAM were unable to adopt prone for hip extension testing. They were able to adopt all other leg muscle testing positions.
All AC's were able to adopt all positions for muscle testing.
Pain due to testing was not a factor for any participants.
The patient experience measure indicated that for some pwHAM, muscle strength testing was similar to a gym exercise session.For the AC's this was not the case.
Conclusion(s): A HHD can be used for muscle strength testing in patients with HTLV infection. A distinctive pattern of muscle weakness: hip extension; knee flexion; ankle dorsiflexion was observed in pwHAM. Despite the excellent ICCs in both groups, indicating high relative reliability, the amount of change needed in pwHAM to indicate true change is too high to be clinically useful.However for AC's the MDC is more promising to use. Subjectively, pwHAM's experience of muscle strength testing was similar to a gym workout indicating that seemingly minimal amount of activity was effortful for them.
Implications: Whilst a HHD is reliable to use in patients with HTLV infection, the minimal clinical difference for participants with HTLV associated myelopathy is too high to be clinically useful.
Keywords: Hand Held Dynamometry, HTLV, Neurology
Funding acknowledgements: Imperial College Charity
Purpose: The purpose of this study is to test a HHD for reliability and acceptability in patients with HTLV infection.
Methods: At the National Centre for Human Retrovirology, 30 patients with HAM (pwHAM) and 22 asymptomatic carriers (AC's) were recruited during routine clinic visits. The study was conducted twice, 4 weeks apart. Participants were randomised to being tested before or after their walking assessments. Standardised testing procedures included 3 tests per muscle group with 10 seconds rest in-between each test. The muscle groups tested were hip flexors/extensors; knee flexors/extensors, ankle plantar/dorsiflexors. Pain scores using a 10cm visual analogue scale, were documented before and after testing.A patient experience measure was completed before and after testing at both sessions.
Analysis: Reliability is reported using the intra-class correlation coefficients(ICC) and its 95% confidence interval and the MDC is calculated as SEM x 1.96 x √2 where SEM =SDx√1-ICC
Results: 52 participants were included in the study: 30 pwHAM and 22 AC's.
Mean age was 59.5 years in pwHAM compared to 51.5 years in AC's.
Median testing times were similar at baseline and follow up: for pwHAM was 18 minutes compared to 15 minutes in AC's.
Reliability, measured by the Intraclass Correlation Coefficient, was excellent for all lower limb muscle groups tested in pwHAM (ICC=0.84-0.95) & AC's (ICC= 0.82-0.95).
The minimal detectable change for pwHAM ranged from 13.3 Newtons- 25.3 Newtons(24.8%-62.1%) compared to AC's 18.6Newtons-29.4Newtons(13.6%-21.6%).
Feasibility of testing positions:2/30 pwHAM were unable to adopt prone for hip extension testing. They were able to adopt all other leg muscle testing positions.
All AC's were able to adopt all positions for muscle testing.
Pain due to testing was not a factor for any participants.
The patient experience measure indicated that for some pwHAM, muscle strength testing was similar to a gym exercise session.For the AC's this was not the case.
Conclusion(s): A HHD can be used for muscle strength testing in patients with HTLV infection. A distinctive pattern of muscle weakness: hip extension; knee flexion; ankle dorsiflexion was observed in pwHAM. Despite the excellent ICCs in both groups, indicating high relative reliability, the amount of change needed in pwHAM to indicate true change is too high to be clinically useful.However for AC's the MDC is more promising to use. Subjectively, pwHAM's experience of muscle strength testing was similar to a gym workout indicating that seemingly minimal amount of activity was effortful for them.
Implications: Whilst a HHD is reliable to use in patients with HTLV infection, the minimal clinical difference for participants with HTLV associated myelopathy is too high to be clinically useful.
Keywords: Hand Held Dynamometry, HTLV, Neurology
Funding acknowledgements: Imperial College Charity
Topic: Neurology
Ethics approval required: Yes
Institution: Imperial College Healthcare NHS trust
Ethics committee: Southwest Central Bristol
Ethics number: 16/SW/0228
All authors, affiliations and abstracts have been published as submitted.
