Purpose

To compare the contribution of physical, psychological and social indicators to predicting disability after one year between consulters with low back pain (LBP) of less than 3 months duration and more than 3 months duration.

Background: LBP Epidemiological studies have identified important causal and prognostic factors, but these frequently only identify a proportion of the variance, and new factors add little to these models. Recently, interest has increased in studying diseases over the lifecourse, a move accompanied by crucial conceptual and methodological developments. This has resulted in improvements in the understanding of conditions such as cardiovascular and respiratory disease.

Aim: To examine how conceptual frameworks from lifecourse epidemiology could enhance LBP research.

Method and Results: Concept 1: patterns over time, risk chains and accumulation. Simple ‘chains of risk’ have been studied, e.g. depression leading to LBP, but studies involving more risk factors in the chain are infrequent. Also, we have not examined how risk accumulation influences outcome, e.g. whether multiple episodes or duration of depression, throughout the lifecourse, better predicts LBP. One-year LBP trajectories have been described, but descriptions of longer-term patterns with associated transitions and turning points are lacking. Concept 2: influences and determinants of pathways. LBP studies commonly adjust for confounders, but factors modifying risk, or related to resilience or susceptibility to LBP, are rarely studied. Concept 3: timing of risk. Studies of critical or sensitive periods – crucial times of life which influence later health in life – are scarce in LBP research.

Conclusion: LBP researchers should develop hypotheses and models of how risks from different stages of life might interact and influence the onset, persistence and prognosis of LBP throughout the lifecourse. Adoption of concepts and methods from lifecourse epidemiology could facilitate this.

Purpose of the study: The aim of this ongoing research is to develop and utilise an individualised, patient-centred approach to outcome measurement in LBP. Specifically, we aim to develop an assessment tool capable of defining “clinically meaningful change” within each patient.

Background: Much work has been dedicated to identifying a definition of successful outcome in LBP. A consensus meeting suggested that 5 discrete domains merit measurement (back specific function, generic health status, pain, work disability and patient satisfaction). Validated tools exist which measure each of these domains. However, how to define what constitutes a “clinically meaningful improvement” as distinct from a “statistically significant change” remains problematic.

Patient satisfaction has been identified as a key dimension in the assessment of outcome in LBP. However what outcome is important to the patient is often not considered, or is poorly assessed. Goal Attainment Scaling (GAS) is a method for systematically targeting individualised goals, and quantifying their achievement. This will provide a valid outcome measure of genuine importance to the patient.

Methods: A semi-structured interview is being developed around the principles of GAS, but specifically modified to elicit patient identified individualised goals that incorporate a marker of “minimum important change” within each scale.

Results: Pilot work has shown that patients can identify meaningful individual goals, which will serve as individualised outcome measures. Furthermore, the notion of achieving a “minimum important change” based around these concepts and within these target scales appears to be generally understood.

Conclusions: Development of an individualised assessment tool capable of defining “clinically meaningful change” within each patient is ongoing. Future work will focus on identifying associations between this individualised outcome and other widely used measures in LBP research, and in establishing the clinical practicality of this approach for use in treatment trials.

The intention is not to attempt a review of outcome instruments, but to select a few themes at random for debate and discussion.

Outcome measures have taken on two meanings: desirable results of interventions and methods of distinguishing subgroups. It is important to separate the two.

Instruments and measures which classify back pain into subgroups need, in clinical or public health terms, to identify characteristics of individual or groups which,. measure impact or severity, estimate prognosis or help to select treatment or guide prevention.

Measures of outcome need to identify characteristics relevant to the objective of the particular study. Such measures may or may not be immediately relevant to the wellbeing of the individual or the group.

To illustrate these rather abstract points, I will use the examples of muscle volume, anxiety about injury, and lifting heavy weights, and consider the concepts of impairment, disability and handicap.

There are now many multiple-item questionnaires covering general health status and different dimensions of health, including the specific impact of back pain on everyday activity. Change over time in scores derived from these are often validated by comparing one with another or with a simple question to the patients as to whether they feel better or not. There needs to be more justification and clarity concerning the added value of these complex questionnaires, since the logical question at the moment is why not simply rely on the patient to tell us whether they are better or not?

Interesting attempts to fill this gap between the “objective instrument” and the patient’s global well-being include the concept of clinically important change and the idea of measuring change in an item rated by the individual patient as the most urgent or desirable to improve. Both in the end depend though on that simple question of whether the patient feels better or not.

The difficulty with patient-centred outcome measures is that many of them imply a very narrow model of change. There are other perspectives to be considered.

Society-centred measures of desirable outcome – less work loss, fewer welfare payments, less health care use. These need not be seen as negative: they imply better rehabilitation, improved facilities, effective prevention. In effect though they are outcome measures for social change rather than targets for the individual back pain sufferer.

Redefining expectations. A big challenge for outcome research is how to incorporate the idea, long a part of therapist technique, that a patient’s expectations can be redefined and targets set which are achievable but which do not necessarily coincide with items on a disability scale. A crude example is the idea that someone’s measurable disability may continue but they are able to work more happily and productively.

Outcome measurement at the moment does not take into account the pattern of back pain over time. Epidemiological studies confirm that back pain for the individual is often a recurrent, intermittent affair, with little evidence that treatment dramatically alters long-term experience. Yet short-term benefits will add up over time in a recurrent condition. Rather than being pessimistic about lack of long-term change in some of our current outcome measures we should aim to measure reduction in the density of pain over time and measure changes in the adaptation of back pain sufferers to society and of society to back pain suffering.