Content validity and clinical meaningfulness of the HFMSE in spinal muscular atrophy

Abstract

BackgroundReports on the clinical meaningfulness of outcome measures in spinal muscular atrophy (SMA) are rare. In this two-part study, our aim was to explore patients’ and caregivers’ views on the clinical relevance of the Hammersmith Functional Motor Scale Expanded- (HFMSE).MethodsFirst, we used focus groups including SMA patients and caregivers to explore their views on the clinical relevance of the individual activities included in the HFMSE. Then we asked caregivers to comment on the clinical relevance of possible changes of HFMSE scores over time. As functional data of individual patients were available, some of the questions were tailored according to their functional level on the HFMSE.ResultsPart 1: Sixty-three individuals participated in the focus groups. This included 30 caregivers, 25 patients and 8 professionals who facilitated the discussion.The caregivers provided a comparison to activities of daily living for each of the HFMSE items.Part 2: One hundred and forty-nine caregivers agreed to complete the questionnaire: in response to a general question, 72% of the caregivers would consider taking part in a clinical trial if the treatment was expected to slow down deterioration, 88% if it would stop deterioration and 97% if the treatment was expected to produce an improvement.Caregivers were informed of the first three items that their child could not achieve on the HFMSE. In response 75% indicated a willingness to take part in a clinical trial if they could achieve at least one of these abilities, 89% if they could achieve two, and 100% if they could achieve more than 2.ConclusionsOur findings support the use of the HFMSE as a key outcome measure in SMA clinical trials because the individual items and the detected changes have clear content validity and clinical meaningfulness for patients and their caregivers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12883-017-0790-9) contains supplementary material, which is available to authorized users.

Nusinersen for SMA: expanded access programme

“…While the maximum and long-term response is not yet clear, at the end of the phase III randomised controlled trial on infants with symptomatic SMA type 1, 51% achieved a motor milestone response, including head control (22%), rolling over (10%), sitting independently (8%) and the ability to stand (1%) 9. Stabilisation or some improvement in motor function is considered clinically meaningful by patients and their families,19 and in this context our results suggest a shift in addressing nutritional and pulmonary issues earlier in newly diagnosed patients, and considering introducing proactive measures in the more severe phenotypes.…”

A qualitative study of perceptions of meaningful change in spinal muscular atrophy

“…Our findings are consistent with two recent studies of SMA patients and family conducted in Europe. Pera et al [33] reported that HFMSE instrument items had content validity based on results of focus groups with patients, caregivers and professional. For their participants, the instrument items encompassed important constructs related to meaningful change.…”

Revised upper limb module for spinal muscular atrophy: 12 month changes

“…The change values were clustered in three groups: patients with stable results (± 2 points), those with loss of more than 2 points and those with improvements of more than 2 points. The cut‐off of two points was decided on the basis of the experience with the HFMSE and based on patients and carers’ questionnaires reporting that any improvement (equal to two points on the scale) was clinically meaningful to patients and their carers . The percentage of patients within each group were compared across age classes by a chi‐square test (a multinomial model was used to adjust for baseline values).…”

“…The cut-off of two points was decided on the basis of the experience with the HFMSE and based on patients and carers' questionnaires reporting that any improvement (equal to two points on the scale) was clinically meaningful to patients and their carers. 7 The percentage of patients within each group were compared across age classes by a chi-square test (a multinomial model was used to adjust for baseline values). Table 1 summarizes the background characteristics of the cohort.…”