“The impact of cancer scale” version 1: psychometric testing of the Norwegian translation in a heterogeneous sample of cancer survivors

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.

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.

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.

In our big heterogeneous sample of LTSs, the Norwegian version of the IOC-1 showed discriminant and concurrent validity, and
reliability was supported.