THE SICKNESS IMPACT PROFILE - SIP68, A SHORT GENERIC VERSION - FIRST EVALUATION OF THE RELIABILITY AND REPRODUCIBILITY

In previous research a short version of the Sickness Impact Profile (S IP136) was developed, containing 68 items. This SIP68 is intended as a short generic alternative to the original SIP. High reliability of th e SIP68 was reported when it was extracted from the SIP136. This paper is a report on the first reliability testing of the SIP68 administere d as an independent instrument without the context of the SIP136. To e stablish the test-retest reliability and the internal consistency of t he new instrument, 51 patients of an outpatient department of rheumato logy completed the SIP68 twice, with an interval of 48 hours. To compa re the performance of the independent SIP68 with the SIP68 extracted f rom the SIP136, the SIP136 also was completed two times by the same 51 respondents. Test-retest reliability for both administration types wa s assessed by means of the intraclass correlation coefficient and the Jaccard's similarity ratio. Internal consistency was assessed by means of Cronbach's alpha. The reliability appears to be high in both the i ndependent SIP68 as well as the extracted SIP68. Moreover, the reliabi lity of the independent SIP68 appears to be as high as for the SIP136. These findings were very encouraging, indicating that the SIP68 may v ery well serve as a generic alternative to the SIP136.