The Swedish version of the Insomnia Severity Index: Factor structure analysis and psychometric properties in chronic pain patients

Although short, the four-item Insomnia Severity Index (ISI-4) version seemed to effectively assess insomnia in chronic pain patients. An important clinical implication is that the four-item Swedish Insomnia Severity Index can be used in chronic pain cohorts when screening for insomnia problems. Its measurement and structural invariance property across the two sexes shows that the ISI-4 is a valid measure of the insomnia across groups of chronic patients. Our results also suggest its utility both in pain clinical practice and research purposes.