Abstract
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.
The abstracts were prepared by Dr C Pither. Correspondence should be addressed to him at the British Orthopaedic Association, Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PN
