Depressive disorder as a long-term antecedent risk factor for incident back pain: a 13-year follow-up study from the Baltimore Epidemiological Catchment Area Sample
Background. The co-occurrence of affective distress and back pain is well documented but the relationship between them is less certain. This study examines the relationship between lifetime occurrence of depressive disorder and incident back pain reported over a 13-year period.Method. The Baltimore Epidemiologic Catchment Area Study is a prospective study of a household-residing cohort, selected probabilistically from East Baltimore in 1981. Between 1982–3 (wave 2) and again between 1993–6 (wave 3), a follow-up study of the original cohort was conducted. Questions on depressive disorder and back pain were drawn from the Diagnostic Interview Schedule. Logistic regression analyses were used to evaluate whether depressive disorder acts as a risk factor for incident back pain.Results. In cross-sectional analyses, lifetime occurrence of depressive disorder was a significant correlate of lifetime prevalence of back pain at wave 1 (OR=1·6, P=0·01). During the 13-year follow-up, across three data collection points, there was an increase in the risk for incident back pain when depressive disorder was present at baseline (OR=1·9, 95% CI 1·03, 3·4). However, during the short-term follow-up period of 1 year, between baseline and wave 2, depressive disorder at baseline was unrelated to first-ever reports of back pain. Lifetime depressive disorder in both waves 1 (baseline) and 2 (1 year later) was associated with a more than three times greater risk for a first-ever report of back pain during the 12 to 13 year follow-up period, in comparison to those who did not have depressive disorder at waves 1 or 2 (OR=3·4, 95% CI 1·4, 7·8). Back pain at wave 1 was not significantly associated with an increased risk for depression in the longitudinal analysis (OR=0·8, 95% CI 0·5, 1·4).Conclusions. Depressive disorder appears to be a risk factor for incident back pain independent of other characteristics often associated with back pain. Back pain is not a short-term consequence of depressive disorder but emerges over periods longer than 1 year. Moreover, in this study the alternative pathway of back pain as a risk factor for depressive disorder could not be supported.