Purpose: The impact of cancer scale version 1 (IOC-1) from 2006 has only been tested psychometrically in a heterogeneous sample of 193 American long-term cancer survivors (LTSs). The Norwegian version of IOC-1 compares the psychometric findings of that study with those observed in a heterogeneous sample of 809 Norwegian LTSs.
Methods: We performed exploratory (EFA) and confirmatory (CFA) factor analyses, tests of internal consistency, correlational studies with various other tests and a change over time examination in order to test reliability and validity of the IOC-1.
Results: The American factor structure of the IOC-1 with 10 dimensions showed adequate fit with CFA in the Norwegian sample, but internal consistency was insufficient in 2 dimensions. EFA of the Norwegian sample found a 9 factor solution that also showed adequate fit on CFA, and with sufficient internal consistencies for all dimensions. The SF-36 dimensions, anxiety, depression, neuroticism, fatigue and body image all showed low correlations with the positive dimensions of the IOC-1, but higher correlations with the IOC-1 negative dimensions. The IOC-1 dimensions showed considerable stability over time.
Conclusions: In our big heterogeneous sample of LTSs, the Norwegian version of the IOC-1 showed discriminant and concurrent validity, and reliability was supported.