The correlation between illness perception, pain intensity and quality of life in elderly with low back pain in Denmark: a cross-sectional study

Background Illness perception is related to management patterns and pain intensity, but among elderly with low back pain, this relation is unclear. The aims of this study were to analyse the associations between illness perception, pain intensity and health related quality of life in a group of elderly with low back pain and explore how different illness perception profiles would cluster and differ in terms of pain, quality of life and choice of management. Method This was a cross-sectional survey based on a cohort of originally 640 Danish children. Of the 311 respondents in 2019, 69% reported low back pain within last year and were included. Associations between illness perceptions (Brief illness perception questionnaire), health related quality of life (EuroQol-5 Domain-3L) and low back pain intensity were assessed, and participants were clustered based on their perceptions using hierarchical and K-means cluster analysis. Cluster differences in pain, quality of life and use of pharmacological and non-pharmacological treatments were explored. Results Among the 213 individuals with low back pain, 33% reported severe or fluctuating pain intensity. Higher pain intensity was associated with perceiving low back pain as a greater threat. Participants reporting fluctuating pain perceived their low back pain almost as threatening as participants reporting severe pain. Two clusters were identified. Cluster 1 reported lower quality of life (difference in medians: −0.176 (95% CI [−0.233–−0.119 ])) and was more likely to report severe or fluctuating pain (37.7% vs. 4.5% [P < 0.0001]) and to use pharmacological treatments than Cluster 2 (37.7% vs. 14.9% [P < 0.001]). No association was found between clusters concerning use of non-pharmacological treatments (P = 0.134). Conclusion Based on illness perceptions, two clusters differing in pain intensity, quality of life and use of pharmacological treatments were identified. Targeting illness perceptions may be beneficial during rehabilitation or when guiding patients with low back pain in choice of management.