The principle finding of this review is the striking lack of consistency among measures of recovery from LBP. Of the 82 studies published in the last 10 years that measured recovery as an outcome, very few did so in exactly the same way. These data perhaps reflect the paucity of investigation into the concept of recovery from LBP [5
]. Irrespective of the reason, this lack of standardisation has important implications for the comparability and interpretation of the LBP literature.
Researchers assessed various related domains as surrogate measures of recovery, examples include; pain, disability and return to work, alone or in combination. The use of a range of domains reflects differing ideas among researchers as to how best to conceptualise recovery from LBP. For example, should the absence of pain denote recovery [17
] or the absence of disability [44
] or are both domains relevant [73
]? Even when recovery is based on a single domain, e.g. pain, there remains the question of whether low levels of residual symptoms indicate recovery or complete absence of symptoms is necessary. Decisions regarding the domain, instrument and cut-off appear in most cases to have been made arbitrarily by researchers, perhaps because there is no uniform definition of recovery.
A range of methods were used to measure recovery, including: previously validated instruments, administrative/insurance data, or direct questions. There were also however a significant number of reports (more than 25% of measures) that provided only an imprecise description of their recovery criterion. Further, only a minority of studies reported the duration for which subjects must meet the specified criteria in order to be regarded as recovered. These findings highlight an important limitation in the recent literature; inadequate reporting of outcome measures provides a barrier to interpretability and comparability of research.
A number of studies assessed recovery via a single-item question, with either a dichotomous response or scored on a continuous/Likert scale anchored by ‘completely recovered’ or similar. A single-item measures may suffer from poorer reliability than multi-item measures [72
] and there is also a conceptual obstacle in that it would seem unlikely that a complex process such as recovery can be adequately captured by a single-item measure. This method does however enable the researcher to assess the subject’s overall perspective of their recovery, ensuring relevance of the measure. This is in contrast to the approach outlined above, where the researchers determine what domains they regard as important in the subject’s recovery. Although this prescriptive approach offers advantages in terms of subject-to-subject comparability, the importance of incorporating patients’ views into outcome measurement has been increasingly recognised recently [5
]. Research in this area suggests patients’ perspectives of recovery are idiosyncratic and often determined by individual appraisal of the impact of symptoms on daily activities and quality of life [51
A relevant question is whether recovery should be considered a dichotomous or a continuous construct. Most of the included studies described recovery as dichotomous; dividing participants into exclusive categories of ‘recovered’ or ‘not recovered’ according to set criteria. On the other hand, several studies (see Table ) used a recovery scale with between 4 and 14 points to place subjects along a recovery continuum. The former approach offers the advantage of simplicity for interpretation, but will almost certainly provide a less responsive measure of patient recovery. This consideration, along with their particular conceptualisation of recovery will direct researchers’ decision on what type of scale to use.
It is perhaps not surprising that wide variability exists in the measurement of recovery in LBP. Indeed, this situation is not uncommon in health-care research. Lack of standardised definitions for key terms and outcomes is noted in studies of whiplash-associated disorders [57
], drowning [75
], falls [41
], spasticity [65
], peptic ulcers [103
] and schizophrenia [58
]. This finding is likely due to the lack of a standardised measure for recovery as well as the absence of a clear and agreed-upon definition of what recovery from LBP means.