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.