Illness perceptions and illness behaviours in back pain: A cross-sectional cluster analysis.

Background: Individuals' perceptions of back pain may shape what they do in response to manage their pain, for example, self-care, medication and seeking healthcare. Illness perceptions encompass a variety of beliefs such as how long pain is expected to last and whether treatments are perceived to control pain. Whether these beliefs meaningfully cluster and whether these clusters are associated with how people manage their back pain are currently unknown.

Methods: 1,343 individuals with back pain from a general population sample completed the brief Illness Perceptions Questionnaire and measures about their pain and illness behaviours. Using a two-stage cluster analysis, we identified four distinct clusters of individuals. Logistic regression was used to investigate relationships between cluster membership and illness behaviours.

Results: After adjustment for socio-demographic characteristics, pain severity, interference and duration, relative to a low threat illness perception cluster, a high threat cluster was more likely to have contacted a general practitioner (OR: 3.03, 95% CI: 1.75, 5.23) and a moderate threat-high treatment control cluster was more likely to have consulted a physical therapist (OR: 2.21, 95% CI: 1.26, 3.87). Both the moderate threat-high treatment control cluster and high threat cluster were also less likely to have reported self-care (OR: 0.64, 95% CI: 0.43, 0.95; OR: 0.53, 95% CI: 0.34, 0.83, respectively).

Conclusions: The cluster analysis provided a meaningful classification of individuals based on their cognitive illness perceptions of their back pain, as these clusters were associated with different illness behaviours. Interventions which modify clusters of illness perceptions may be effective in influencing how individuals respond to back pain.

Significance: Within a general population setting, we identified four clearly distinct groups of people based on the perceptions they held about their back pain. These groupings seemed to reflect meaningful characterisations as they differed based on the characteristics of their pain (e.g., severity and duration) and, after adjustment for these characteristics, were associated with different ways of managing pain. Interventions which focus on targeting the sets of illness perceptions that people hold may be effective in influencing how individuals manage back pain.