BACk Pain in Elders in Norway (BACE-N); A Prospective Cohort Study of Older People Visiting Primary Care With a New Episode of Back Pain

Back pain represent a considerable burden worldwide, and is predominantly managed in primary care. Between 2010 and 2050, the number of people aged 60 years and older will increase by 56% in developed countries, and this transition will increase the burden of chronic back disability. Most previous studies on (low) back pain have excluded people above 60 years of age, leading to a large knowledge gap regarding the prognosis of back-related disability and pain in older people and which factors influence the transition from acute to chronic stage. Further, back pain outcomes used in the few existing studies are not selected to capture the burden and characterization of back pain in older people. Therefore, the international Consortium (BACk pain in Elders: BACE) was established in 2008 in order to create standardised methodology for large cohort studies and share data on the burden of back pain in older people. BACE cohort studies have been established in several countries, also currently in Norway, with the primary objective to establish the clinical course and burden of back pain in elderly, to identify prognostic factors for chronic back pain and disability, and to explore usual care provided in primary care.

Specific aims for the BACE-N are:

1. Explore potential differences in baseline characteristics, including main domains of measurements of putative prognostic factors and outcomes, across patients who seek general practitioner, physiotherapist and chiropractor in primary care
2. Establish the 1- and 2-year clinical course (overall prognosis) and burden of back-related disability (defined as the primary outcome)
3. Establish the 1- and 2-year clinical course (overall prognosis) and burden of pain (severity, location/radiation/neurological signs, stiffness, sleep, and use of pain medication)
4. Describe usual care provided in the primary care (for the initial episode of back pain) and cost of illness due to total healthcare consumption (including secondary care such as hospitalisation and institutionalisation) and production loss during one year of follow-up
5. Assess the association between established prognostic factors in the middle-aged back pain population (comorbidity and psychosocial profile) and back-related disability at 1-and 2-years follow-up
6. Develop and validate a prognostic model for long-term back-related disability at 1- and 2-years follow-up in these people
7. Explore prognostic factors associated with persistent and/or recurrent back pain at 1- and 2 years follow-up
8. Explore prognostic factors associated with costs of illness during 1-year of follow-up
9. Establish the 1- and 2-year incidence of falls and loss of independence (Falls Efficacy Scale) and explore prognostic factors associated with falls and loss of independence during 1- and 2-year of follow-up
10. Assess the clinical course (overall prognosis) in main outcomes (disability, pain, and costs of illness) across patients who seek general practitioner, physiotherapist and chiropractor in primary care.
11. Assess gender differences in clinical course, prognostic factors and usual care in these people.

In addition to these specific aims, the BACE-N includes several methodological studies as several of the measurements from the original BACE protocol had to be translated and validated for a Norwegian context.

The study design is a prospective observational cohort study with linked methodological studies within a primary care setting, recruiting 450 patients from three main back pain health professionals; general practitioners, physiotherapists and chiropractors. The patients are followed by questionnaire at 3, 6, 12 and 24 months after inclusion. The data collected in the BACE-N adheres to the standardised methods described in the published protocol from 2011 (Scheele J, Luijsterburg PA, Ferreira ML, Maher CG, Pereira L, Peul WC, et al. Back complaints in the elders (BACE); design of cohort studies in primary care: an international consortium. BMC Musculoskelet Disord. 2011;12:193). Likewise, the statistical approach adheres to the original plan and the PROGnosis RESearch Strategy (PROGRESS), covering overall prognosis research, prognostic factor research, and prognostic model research. The methodological studies in the BACE-N are conducted in line with the COSMIN recommendations. A protocol for the BACE-N will be registered.