The Cutoff Value, Validity, and Reliability of the Japanese Cold Intolerance Symptom Severity Questionnaire

Abstract

The Cold Intolerance Symptom Severity (CISS) questionnaire was introduced by Irwin as a tool for measuring cold intolerance of hand patients. Although there have been many articles on cold intolerance and CISS from Europe, a very few were from Asia. We translated the CISS into Japanese. The aim of this study was to identify a cutoff value for the Japanese CISS in normal population and to evaluate its validity and reliability in hand patients. Translation Process: The original CISS was translated into Japanese by 2 Japanese professional translators independently. The 2 translations were synthesized and then translated backward into English by 2 professional English native translators. An expert panel, consisting of translators, a hand surgeon, and hand therapists, was held to finalize the Japanese CISS. Materials and Methods: One hundred forty-three healthy volunteers answered the Japanese CISS during winter season. The cutoff value was determined using 95% confidence interval. The validity and reliability of the Japanese CISS in hand patients were also investigated. During winter season, 111 outpatients with hand injuries completed the questionnaire and Disabilities of the Arm, Shoulder and Hand (DASH) (9 nerve injuries, 18 finger replantations, 11 tendon injuries, 24 phalangeal fractures, 35 distal radius fractures, 10 complex injuries, and 4 others). The mean age was 52.8 years (range, 16-84). To evaluate the test-retest reliability, 62 patients answered the questionnaire again with a 2-week interval. Statistical Analysis: DASH was used to assess concurrent validity of the Japanese CISS. The Spearman correlation was calculated to assess the correlation between the Japanese CISS and DASH. To evaluate the reliability of the Japanese CISS, Cronbach alpha and the intraclass coefficient (1.1) were calculated for internal consistency and test-retest analysis. Results: In a normal Japanese population, the average CISS score was 16.3 (standard deviation [SD], 15.2). Scores more than 50 were considered to show abnormal cold intolerance. In the hand patients, Spearman correlation between the Japanese CISS and DASH was 0.358, suggesting modest correlation. Cronbach alpha and the intraclass coefficient were 0.917 and 0.896, respectively, which showed the internal consistency, and the testretest reliability of the Japanese CISS was both very good. Discussion: A cutoff value of the Japanese CISS was 50; it was similar to that of the Swedish version of the CISS. The Japanese version of the CISS was proved to be reliable with high internal consistency and test-retest reliability. It indicates good conceptual equivalence of Japanese version and comparability of interpretation.