A blinded validation of the Swedish version of the Clinical Assessment Interview for Negative Symptoms (CAINS)

The Clinical Assessment Interview for Negative Symptoms (CAINS) was developed in order to advance the assessment of negative symptoms. The aim of this study was to validate the Swedish version of the CAINS.

Thirty-four out-patients with a schizophrenia spectrum disorder were recruited. All patients were videotaped while interviewed with the CAINS and the Brief Psychiatric Rating Scale (BPRS). Another rater watched the video recordings in the reverse order, enabling a blinded design. The patients also filled in self-reported measures of depression, quality of life, and social and vocational functioning. We calculated inter-rater agreement and internal consistency for the CAINS. We also calculated validity measures by correlating the subscales Motivation and Pleasure (CAINS-MAP) and Expression (CAINS-EXP) to subscales of the BPRS.

The blinded inter-rater agreement for the CAINS total score was high (ICC = 0.92) but slightly lower for the expression subscale (ICC = 0.76). Cronbach's alpha was 0.84 for the total score. Convergent validity with the negative symptoms subscale of BPRS was different for the blinded and the unblinded data, with a CAINS-MAP correlation of 0.10 (p = 0.580) and a CAINS-EXP correlation of 0.48 (p = 0.004) in the blinded data. The unblinded data had a CAINS-MAP correlation of 0.38 (p = 0.026) and a CAINS-EXP correlation of 0.87 (p < 0.001). Self-rated measures of anhedonia correlated to CAINS-MAP with a coefficient of 0.68 (p < 0.001), while the CAINS-EXP only had a correlation of 0.16 (p = 0.366) to these measures.

The Swedish version of the CAINS displays adequate psychometric properties in line with earlier validation studies.