Validating a fear‐of‐falling‐related activity avoidance scale in lower limb prosthesis users

Introduction

Limited available data suggests fear of falling (FoF) may be common among lower limb prosthesis users (LLPUs) and associated with negative rehabilitation outcomes. The impact of FoF on outcomes may be exacerbated when fear leads to self‐imposed declines in activity. There is a need to identify the validity of fear‐of‐falling‐related activity avoidance scales in LLPUs .

Objective

To evaluate the convergent, discriminant and known‐group construct validity of the modified Survey of Activities and Fear of Falling in the Elderly (mSAFE) for LLPUs. Secondarily, we sought to determine if the mSAFE scale could be reduced without losing information regarding construct validity.

Design

On‐line survey

Setting

Not applicable

Participants

Fifty‐nine persons with unilateral or bilateral amputation at the transtibial or transfemoral level, with ≥6 months experience using a definitive prosthesis for activities other than transfers.

Intervention

Participants completed an online survey that consisted of the mSAFE and questions to assess FoF (yes/no), fear‐of‐falling related activity avoidance (yes/no) as well as previously validated scales capturing related and unrelated constructs. T‐tests were used to compare mSAFE score between yes/no respondents for known‐group construct validity. Correlations between mSAFE and previously validated surveys assessed convergent and discriminant validity. Analyses were repeated on a reduced number of mSAFE items following a redundancy analysis.

Main outcome measures

Not applicable

Results

Significant correlation coefficients of |0.440‐0.825| were found for convergent validity with evidence of known‐group construct validity (p<0.021 for all comparisons). There was evidence for discriminant validity, with non‐significant associations for two‐of‐three correlations. Results from validity analyses were similar for a shortened six‐item mSAFE as for the full scale.

Conclusion

This study provided initial evidence regarding validity of the mSAFE as a measure to assess fear‐of‐falling‐related activity avoidance in LLPUs. A 6‐item scale may be appropriate if the full scale would be taxing or time consuming.

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