Patients with symptoms of depression are at increased risk of developing a new episode of low back pain compared with those who are not depressed, a meta-analysis has found.
Analysis also showed that the more severe the depression, the greater the risk of low back pain.
In a pooled analysis of 19 studies, 11 of which were incorporated into the meta-analysis, symptoms of depression increased the risk of developing low back pain by almost 60% compared with an absence of depression (odds ratio (OR) 1.59, 95% CI 1.26-2.01).
Among three studies where severity of depression was categorized, subjects with the most severe depression had a 2.5-fold increased risk of experiencing an episode of low back pain (OR 2.51, 95% CI 1.58-3.99) compared to those with the lowest level of depression.
Those with the lowest level of depressive symptoms still had a 50% greater chance of experiencing an episode of low back pain at an OR 1.51 (95% CI 0.89-2.56).
The odds of developing low back pain were also similar whether studies used the diagnostic interview method (OR 1.66, 95% CI 1.14-2.42) or a self-report screening questionnaire (OR 1.68, 95% CI 1.05-2.70) compared with the overall analysis.
In contrast, studies using nonspecific screening questionnaires showed no significant association between psychological distress and the risk of developing low back pain.
“The etiology of low back pain is poorly understood and the identification of possible causal factors or the role of co-morbidities that would potentially lead to low back pain could contribute to effective management strategies,” Marina Pinheiro, MSc, of the University of Sydney, and colleagues wrote in Arthritis Care and Research.
“As current conservative treatments for low back pain have only shown small to moderate effects, the results of this review point to an additional treatment model where the focus of low back pain management could be extended from treating specific impairments … to the management of associated co-morbidities such as depression.”
A total of 19 articles reporting data from 16 studies were included in the review, and overall pooled results from 11 studies were analyzed.
As investigators point out, age was a potential confounder in the relationship between depression and low back pain because when studies that included only older participants were pooled, older depressed patients had almost a twofold risk of developing a new episode of low back pain at an OR 1.59 (95% CI 1.40-2.181) compared with the overall pooling of the primary analysis.
It is possible that depression has a stronger effect on the risk of low back pain in older subjects, the authors suggest, because low back pain tends to be more disabling in older individuals, and risk factors for low back pain tend to be related to health status and performance which often decline with age.
“Therefore, it is plausible that symptoms of depression further debilitate older people, putting them at higher risk of developing low back pain, or affecting pain threshold, compared to younger individuals,” they observe.
A possible explanation for the association between depressive symptoms and low back pain might include a biological link between the two.
“These conditions share common biological pathways and neurotransmitters such as serotonin and norepinephrine,” investigators point out.
“And a deficiency of these neurotransmitters [could be] expected to affect both mood and pain thresholds, possibly explaining the relationship between [the two].”
Alternatively, changes in lifestyle among those affected by depression could potentially lead to low back pain.
Depressed patients, for example, usually become less physically and socially active and are more likely to suffer from sleep disturbances, factors that have also been related to low back pain.
Genetic factors, too, have been found to substantially contribute to the development of both depression and low back pain so genetics could possibly affect the association by influencing both conditions, they add.
“A potential causal link between symptoms of depression and low back pain is one possible explanation for our findings and it is partially supported by the dose-response relationship we found,” the authors state.
“And health professionals should be aware that symptoms of depression might be an additional risk factor for low back pain, especially when managing older people, as this makes appropriate detection and treatment of depression even more important than it currently is.”