Does socioeconomic status in adolescence predict low back pain in adulthood? A repeated cross-sectional study of 4,771 Danish adolescents.

Social and economic disadvantage is associated with general poor physical health. This relationship has been recognised for centuries, but it is unknown whether socioeconomic factors have a specific influence on low back pain (LBP). Furthermore, it is unknown how social and economic disadvantages in youth affect adult health. Therefore, the specific objectives of this study are to explore (1) the cross-sectional association between socioeconomic status (SES) and LBP in adolescence and (2) the longitudinal association between SES in adolescence and LBP in early adulthood. A database containing LBP data from 4,771 twins was merged with their parents' social and economic data, available from Statistics Denmark. Low back pain data ['any low back pain' and 'persistent low back pain (more than 30 days)'] were collected in 1994, when the subjects were 12-18 years of age, and collected again eight years later. Socioeconomic data of the parents (education, income, social class and long-term illness, all for both mother and father) were collected in 1994. Logistic regression analyses were used to estimate the associations between each parameter of parental SES in adolescence and LBP at baseline as well as at follow-up. Finally, the influence of a variable combining the different socioeconomic parameters was established. All estimates were controlled for smoking, alcohol consumption and body mass index at baseline. In the logistic regression models, only three of the 32 estimates were statistically significant. When merging the socioeconomic variables into a combined score, the results indicated that a good social background had a protective effect against the persistent LBP, while there was no association with any LBP. However, the statistical significance of this effect was unclear. We found no or very weak indications of possible relationships between social factors in adolescence and LBP at baseline and at follow-up.