Exploring illness perception classes in the general population: a latent class analysis^†

This study aimed to identify classes of illness perceptions in the Danish general population and examine their association with physical and mental health outcomes.

Latent Class Analysis was conducted on 4,999 participants using the Brief Illness Perception Questionnaire (BIPQ) to identify distinct illness perception classes. Cross-sectional and five-year follow-up analyses explored associations between illness perception class and outcomes including symptom severity, physical functioning, anxiety, depression, and screening for functional somatic disorder (FSD).

Three distinct illness perception classes were identified: untroubled, detached, and distressed. The untroubled class showed positive illness perceptions and favourable outcomes. The detached class showed low perceived control and symptom coherence but did not differ significantly from the untroubled class in outcomes. The distressed class showed negative perceptions of consequences, concern, timeline, and emotional responses and had the poorest health outcomes both at baseline and follow-up, even when adjusting for baseline scores. Class membership was significantly associated with all outcomes cross-sectionally and longitudinally.

Illness perception class membership was associated with long-term physical and mental health. Membership to the distressed class predicted poorer outcomes and higher FSD risk, suggesting that negative illness perceptions may precede negative health outcomes and represent a target for intervention.