A new foot and ankle outcome score: Questionnaire based, subjective, Visual-Analogue-Scale, validated and computerized
Introduction
Outcome assessment has become critical in evaluating the efficiency of both surgical procedures and medical treatments [1], [2], [3]. A wide variety of outcome measures have been proposed for use in conditions affecting the foot and ankle. A validated score for foot and ankle outcome is unavailable [1], [4]. This deficiency was recently established at the American Orthopaedic Foot and Ankle Society's (AOFAS) 2003 and 2005 Annual Summer Meetings [1], [2], [3]. Furthermore, the insufficiency of supposedly objective assessment was clearly stated [1]. Our purpose was to construct and validate a new score taking into consideration the flaws of existing scores.
There are two possibilities for validation:
- (1)
A score is validated for a specific population and language [5], [6]. This requires an enormous case number, as for example more than 3000 subjects for the validation of the German SF-36® version [5]. Worldwide, this type of validation was achieved only for the SF-36® [5], [6]. No foot and ankle score (including the AOFAS score) has ever been validated in that fashion.
- (2)
A score is validated by sufficient correlation with a validated score [7]. Since the SF-36® is the only validated score, this kind of validation is appropriate only by validation with that score [7]. Many scores for different types of diseases and populations have been validated following this principle [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. Thus, no foot and ankle score (including the AOFAS score) has passed through this process as far as we know.
Section snippets
Validation process
Three scores (SF-36®, Hannover Questionnaire (Q) and Visual-Analogue-Scale Foot and Ankle (VAS FA)) were obtained from a group of voluntary subjects. The results were analyzed and correlated to the scores. The time spent for evaluating the different scores was recorded and compared.
Subjects
One hundred and twenty-one subjects were included in the study. The number of subjects was determined by a statistician after a review of the study design and before starting the study. Fifty-eight of the subjects
Score results and correlation
All questions were answered by all subjects.
Table 1 indicates the score results. Table 2 shows the results of the statistical correlation of the three scores. All correlations were significant regarding the defined p < 0.05 level. Sufficient correlation (r > 0.5) was found in all score categories and total scores.
The SF-36® scores did not significantly differ from the actual normative data (age and gender related) of the average German population (data not shown) [18].
Time spent
The time needed evaluating the
Discussion
The gold-standard score for foot and ankle is regarded as the AOFAS score [4], [19], [20], [21]. This score is widely used as shown by the high number of hits when entering the term “aofas score” into the PubMed®-search engine in the World-Wide-Web (National Library of Medicine). However, this score is problematic due to significant flaws as follows. The score is not validated [1], [4], it cannot be obtained if answers are missing, and contains problematic pseudo-objective assessment. To assess
Acknowledgements
The authors thank Ludwig Hoy, Ph.D. (Institute for Biometry, Hannover Medical School, Hannover, Germany) for his help and support in carrying out the extensive statistical analysis and for his unbiased prior evaluation, Hans Werner Kuensebeck, M.D. (Department of Psychosomatics and Psychotherapy, Hannover Medical School, Hannover, Germany) for his assistance during the SF-36® evaluation, and Justin Bender, Ph.D. for his assistance in translating the Visual-Analogue-Scale Foot and Ankle (VAS FA)
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