Psychological and culturally-influenced risk factors for the incidence and persistence of low back pain and associated disability in Spanish workers: findings from the CUPID study

Objective To assess the importance of psychological and culturally-influenced factors as predictors of low back pain (LBP) incidence and persistence in Spanish workers. Methods As part of the international Cultural and Psychosocial Influences in Disability (CUPID) study, 1105 Spanish nurses and office workers answered questions at baseline about LBP in the past month and past year, associated disability, occupational lifting, smoking habits, health beliefs, mental health, and distress from common somatic symptoms. At 12-month follow-up, they were asked about LBP and associated disability in the past month. Associations with LBP incidence and persistence were assessed by log binomial regression, and characterised by prevalence rate ratios (PRRs) with associated 95% CIs. Results 971 participants (87.9%) completed follow-up. Among 579 with no LBP at baseline, 22.8% reported LBP at follow-up. After adjustment for sex, age and occupation, new LBP was predicted by poor mental health (PRR 1.5, 95% CI 1.0 to 2.2), somatising tendency (PRR 1.8, 95% CI 1.2 to 2.7) and presence of LBP for >1 month in the year before baseline (PRR 4.7, 95% CI 3.1 to 6.9). Among 392 subjects who had LBP at baseline, 59.4% reported persistence at follow-up, which was associated with presence of symptoms for >1 month in the 12 months before baseline (PRR 1.4, 95% CI 1.2 to 1.7) and more weakly with somatising tendency, and with adverse beliefs about LBP work-relatedness and prognosis. Conclusions In Spain, as in northern European countries, psychological and culturally-influenced factors have an important role in LBP development and persistence.