A misty, multidimensional crystal ball

Wouldn’t it be great if we could give our patients a prognosis that is evidence based and tailored to their presentation? Chronic low back pain (CLBP) is, however, a complex multidimensional problem, and over 200 factors (from multiple dimensions such as demographics, psychological, social, health and lifestyle etc.) may be prognostic for people with CLBP [1,2]. When a patient in clinic is telling us about their CLBP it’s important to bear these in mind, so we have some idea of the potential trajectory of their complaint. However, despite knowing that CLBP is multidimensional, most prognostic studies have not included large numbers of potentially prognostic, multidimensional variables, so don’t reflect the complex nature of the disorder. This may be one reason why most studies explain less than 50% of the variance in any outcomes studied, i.e. more than half of any change in the outcomes could not be ascribed to the variables that had been considered. So, perhaps we’d be better off peering into a crystal ball.

To attempt to clear the mists drifting across our vision of CLBP’s future, we undertook a prognostic study including 266 people, in which 108 potentially prognostic, multidimensional variables were measured at baseline. These variables included a number of broadly-grouped interventions (e.g. exercise, psychological therapy) [3]. Because perceived recovery is influenced by many factors, we then determined which variables were independently prognostic of pain, disability, global rating of change and bothersomeness one year later.

After hours of statistical analysis to determine how the potentially prognostic variables may have interacted to influence recovery, there were some novel findings…. Where people with pain perceived that their significant other punished them for having their CLBP, this was prognostic of both higher pain intensity and disability one year later. Participating in exercise was prognostic for lower pain, disability and being much / very much improved. Slower speed of movement during forward bending was prognostic of higher disability and greater bothersomeness. The odds of having very / extremely bothersome CLBP were increased by having received injection(s). Interestingly, pain sensitivity and general health variables did not make it into any models.

So….was this multidimensional crystal ball any better at explaining variance in outcomes? Despite inclusion of numerous potentially prognostic, multidimensional variables we were not able to explain a greater proportion of variance in the outcomes measured. Why not? Such prognostic modelling may only reflect prognostic factors that were common across the entire cohort at that one time, while CLBP is heterogenous and in constant flux [4,5,6]…..I sense the mists closing in again, with this crystal ball possibly unlikely to reveal further secrets.

Maybe we need to think differently about CLBP. Complexity theory suggests such disorders may be the product of non-linear, emergent multidimensional interactions, the sum of which cannot account for the entire presentation. Statistical analysis of multidimensional interactions at multiple time points, in very large samples may shed further light on this. Our results also suggest that at this stage the crystal ball is not very helpful to clinicians, who need to consider the lived multidimensional experience at the level of the individual sitting in their clinic.

About Martin Rabey

Martin is a Specialist Musculoskeletal Physiotherapist (As awarded by the Australian College of Physiotherapists, 2009). He completed his PhD at Curtin University in Perth, examining the complex interactions between factors which make low back pain persist. He recently moved back to Guernsey in the Channel Islands, where he was born. There he is a Director of THRIVE, a company with a three-pronged approach: offering education to healthcare practitioners worldwide on the integration of pain science with clinical practice and undertaking international collaborative research into persistent pain disorders, all the while delivering expert physiotherapy to the islanders. In his spare time he is a coasteering guide.

[We at BiM decided that this photo was too good to reduce to the normal thumbnail pics we have of authors!]

References:

[1] Hayden JA, Dunn KM, Van Der Windt DA, et al. What is the prognosis of back pain? Best Prac Res Clin Rheum. 2010; 24:167–179.

[2] Hayden JA. Methodological Issues in Systematic Reviews of Prognosis and Prognostic Factors: Low Back Pain [PhD thesis]. Ann Arbor: University of Toronto (Canada); 2007.

[3] Rabey M, Smith A, Beales D, Slater H, O’Sullivan P. Multidimensional prognostic modelling in people with chronic axil low back pain. Clin J Pain. 2017; 33:877-891.

[4] Rabey M. Multidimensional patient profiles in chronic non-specific axial low back pain: Subgrouping and prognosis. [PhD thesis]. Curtin University (Australia); 2016.

[5] Brown C. Mazes, conflict, and paradox: tools for understanding chronic pain. Pain Prac. 2009;9:235–243.

[6] Bittencourt N, Meeuwisse W, Mendonc¸a L, et al. Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition—narrative review and new concept. BJSM. 2016;50:1309–1314.