Clinical research into the management of low back pain has shown that the current available treatments offer, at best, only moderate effects. Our Spinal Research Group at the University of Sydney has been one of the pioneers in the field and most of these discouraging results have been produced by high quality randomized controlled trials and systematic reviews conducted by our group. Not surprisingly we thought that we needed a change in the course of direction of the spinal management boat.
We realized that a step backwards would be necessary if we wanted to move forward with the design and implementation of interventions for back pain. Stepping back, in this scenario, and in a research group that conducts mainly clinical research, meant that we would have to re-visit some epidemiologic aspects of the condition. From these aspects we thought the most important one would be the investigation of causal factors in back pain.
The systematic review recently published in the European Journal of Pain investigated factors that were associated with, or consistent with, a cause of back pain arising from studies that used twins. The use of twins in back pain research is particularly important because this design allows for a cleaner and more precise estimate of what causes back pain because genetics can be controlled for. In a twin design approach a pair of twins is used in the analysis. When one twin has the condition and the co-twin does not we have the opportunity to use an analysis called twin case-control. This design circumvents the common problem in back pain studies where heterogeneous groups of back pain patients are investigated and the genetic component is disregarded.
The results of this systematic review showed that the genetic component affects 21% to 67% of back pain depending on the type of the condition. Interestingly, genetic influences are higher for more chronic and disabling back pain. Twin studies also showed that smoking and obesity are also associated with back pain even after the genetic component is controlled for.
It does appear that some types of back pain (chronic disabling) have a higher genetic causation component while others (acute or less disabling) have a higher environment component. These findings have important implications for the understanding, prevention and management of back pain. Reducing the occurrence of back pain by controlling causal component factors is a promising field but we need to identify, for different types of back pain, which ones are dominant and necessary factors for the condition to be established.
This study has been used as the framework for a current NHMRC grant proposal submitted by our group aimed at investigating physical activity as a protective or causal factor for back pain using twins registered at the Australian Twin Registry. We are expecting to use the twin design in our future studies as a step forward in the understanding of what causes back pain and how we can optimize our management of this highly prevalent and costly condition.
About Paulo Ferreira
Paulo Ferreira is a Senior Lecturer and the leader of the Spinal Research Group at the Faculty of Health Sciences, University of Sydney, Australia.
Reference
Ferreira, P., Beckenkamp, P., Maher, C., Hopper, J., & Ferreira, M. (2013). Nature or nurture in low back pain? Results of a systematic review of studies based on twin samples Eur J Pain DOI: 10.1002/j.1532-2149.2012.00277.x