Influence of the number and severity of comorbidities in the course of acute non-specific low back pain in older adults: longitudinal results from the Back Complaints in the Elders (BACE-Brazil)

Background The presence of comorbidities is quite common in older adults. However, the effects of comorbidities on the course of acute low back pain (LBP) are not fully understood. Objective To investigate the effects of the number and severity of comorbidities on the severity of pain and disability 3 months from baseline in people with an acute episode of non-specific LBP. Methods Data from the Back Complaints in the Elders study, a cohort that enrolled 602 community-dwelling older adults with acute LBP at baseline, were used in these analyses. Comorbidities, pain intensity and disability were assessed using the Self-Administered Comorbidities Questionnaire (SCQ), the Numeric Rating Scale (NRS) and the Roland–Morris Disability Questionnaire (RMDQ), respectively. Age, sex, marital status, education, income and body mass index were covariates. Results The mean age of participants was 67.6 ± 7.0 years. Both pain and disability scores decreased from 7.2 (95% confidence interval [95% CI] 7.0–7.4) to 5.8 (95% CI 5.5–6.1) in NRS and from 13.5 (95% CI 13.0–14.1) to 12.0 (95% CI 11.4–12.7) in RMDQ 3 months from baseline. The linear regression analysis showed a significant association between SCQ scores at baseline and pain (coefficient = 0.16, 95% CI 0.08–0.24; P < 0.001) or disability (coefficient = 0.29, 95% CI 0.16–0.41; P < 0.001) scores at the 3-month follow-up, after adjusting for confounders. Participants with highest SCQ scores were less likely to report improvement of at least 30% in pain (OR: 0.41, 95% CI 0.22–0.79; P = 0.008) and disability (OR: 0.42, 95% CI 0.28–0.85; P = 0.015). Conclusion The presence and severity of comorbidities were independently associated with the prognosis of acute non-specific LBP in older adults.