Psychometric properties of a Swedish translation of the VISA-P outcome score for patellar tendinopathy

BACKGROUND Self-administrated patient outcome scores are increasingly recommended for evaluation of primary outcome in clinical studies. The VISA-P score, developed at the Victorian Institute of Sport Assessment in Melbourne, Australia, is a questionnaire developed for patients with patellar tendinopathy and the patients assess severity of symptoms, function and ability to participate in sport. The aim of this study was to translate the questionnaire into Swedish and to study the reliability and validity of the translated questionnaire and resultant scores. METHODS The questionnaire was translated into Swedish according to internationally recommended guidelines for cross-cultural adaptation of self-report measures. The reliability and validity were tested in three different populations. The populations used were healthy students (n = 17), members of the Swedish male national basketball team (n = 17), considered as a population at risk, and a group of non-surgically treated patients (n = 17) with clinically diagnosed patellar tendinopathy. The questionnaire was completed by 51 subjects altogether. RESULTS The translated VISA-P questionnaire showed very good test-retest reliability (ICC = 0.97).The mean (+/- SD) of the VISA-P score, at both the first and second test occasions was highest in the healthy student group 83 (+/- 13) and 81 (+/- 15), respectively. The score of the basketball players was 79 (+/- 24) and 80 (+/- 23), while the patient group scored significantly (p < 0.05) lower, 48 (+/- 20) and 52 (+/- 19). CONCLUSIONS The translated version of the VISA-P questionnaire was linguistically and culturally equivalent to the original version. The translated score showed good reliability.