Does Age Affect the Relationship Between Pain and Disability? A Descriptive Study in Individuals Suffering From Chronic Low Back Pain

Background: Previous studies have revealed a weak to moderate relationship between pain and disability in individuals suffering from low back pain (LBP). However, to our knowledge, no studies have evaluated if this relationship is different between young and older adults. Purpose: The objective of this descriptive, cross-sectional study was to determine whether the relationship between LBP intensity and physical disability is different between young and older adults. Methods: Pain intensity (measured with a visual analog scale) and physical disability scores (measured with the Oswestry Disability Index) were collected from the medical files of 164 patients with LBP. Separate Pearson correlation coefficients were calculated between these 2 variables for young (mean age 40 6 years, n = 82) and older (62 +/- 9 years, n = 82) individuals and a Fisher r-to-z transformation was used to test for group differences in the strength of the relationship. Linear regression analyses were also performed to determine whether the slope of the association was different between the 2 groups. Results: A significant and positive association was found between pain intensity and disability for both young and older individuals. However, the correlation was stronger in the young group (r = 0.66; P < .01) than in the older group (r = 0.44; P < .01) (Fisher Z = 2.03; P < .05). The linear regression model also revealed that the slope of the relationship was steeper in the young group (P < .05). Conclusion: Although both young and older individuals showed a significant association between pain intensity and disability, the relationship between these 2 variables was more tenuous in older individuals than in young patients. Future research is essential to identify the factors underlying this age-related difference.