Cross-sectional studies suggest that chronic pain is an important cause of morbidity and disability in the community, affecting around half the population,1,2 and that its management is generally poor.
It may be that management or prevention targeted at identified aetiological factors will be effective in chronic pain in the community, irrespective of its cause. In order to test this hypothesis, a number of questions must be answered:
- What is the natural history of chronic pain in the community, and which physical, psychological and social factors influence this?
- What is the burden of care from chronic pain on the NHS, and which factors determine a heavy burden?
- How do patients and professionals perceive chronic pain, and what do they expect from treatment?
- Are there factors common to the aetiology and development of chronic pain from different causes which suggest that a common intervention could be applied and be equally effective?
- What interventions are available and appropriate for managing chronic pain in primary care?
An NHS R&D Primary Care Award, based on a 5-year research programme, has enabled my colleagues and me to address these questions. Eventually we aim to set up randomised controlled trials (RCTs) to determine which interventions are effective in treating or preventing chronic pain in the community.
We have taken chronic pain as an example of a common chronic condition, which is important in primary care, yet the epidemiology of which remains poorly understood,35 and for which the basic goals of treatment are not clear. Other examples include fatigue, dizziness, and bowel symptoms.6 My contention is that, without this knowledge, not only will we fail to address these problems clinically, but we cannot even design the right trials to evaluate interventions.
It is important that epidemiology does not stop at a description of incidence and prevalence, but includes natural history and progresses towards clinical trials of prevention or management.
While we have detailed epidemiological understanding of relatively rare conditions (e.g. cervical carcinoma), and can see the benefits in terms of prevention and treatment, there remain wide gaps in our epidemiological understanding of common conditions in primary care. Recently, the MRC7,8 and the NHS9 have recognised the importance of these gaps.
We hope to identify subgroups of people who are more likely to be more severely affected by chronic pain, and clinical or psychosocial factors that predict its onset, exacerbation or improvement. This will inform the targeting of intervention strategies.
Surveys and interviews of patients and professionals will inform the design of interventions, and tell us how to judge their success. Detailed information on the natural history is required for accurate sample size estimations and power calculations in RCTs, and will assist interpretation of the results.
As well as a number of published results from this programme,1,2 my colleagues and I have conducted a longitudinal study of chronic pain in Grampian, and have piloted interview schedules for qualitative follow-up studies. We have also validated a series of survey instruments for use as assessment or outcome measures in clinical trials.
We continue to plan health economic and intervention studies as well as more detailed epidemiological studies. We are moving towards RCTs in primary care, and look forward to the potential of these to improve the management of chronic pain.
- My NHS Primary Care Career Scientist Award is funded by the Chief Scientist Office, Scottish Executive, for whose support I am grateful.
- Elliott AM et al. Lancet 1999; 453: 1248-52.
- Smith BH et al. Fam Pract 2001; 18; 292-9.
- Crombie IK. In: Crombie IK et al (Eds). Epidemiology of Pain. Seattle: IASP Press, 1999: 1-5.
- Smith BH et al. J R Soc Med 1996; 89: 181-3.
- Smith BH. Br J Gen Pract 2001; 51: 524-5.
- Wessely C et al. Lancet 1999; 354: 936-9.
- MRC. Topic Review, Primary Health Care. London: MRC, 1997.
- MRC. MRC Strategic Review of Future Support for Epidemiology. London: MRC, 1999.
- NHS Central R&D Committee. R&D in Primary Care. National Working Group Report (The Mant Report). London: NHS Executive, 1997.