Department of Rheumatology, Concord Hospital, NSW 2139, Australia
SIR, The article by Rasmussen et al. [1] concerning cervicobrachial pain and compensation is an important attempt to answer a vexed question. However, I am concerned that the assertions made in this article cannot be sustained on careful scrutiny of the methods and results.
First, it is stated that the only information on the patients at the time of referral came from the referring practitioner's letter. In my own country, this letter often provides ample evidence of whether the patient was involved in compensation (e.g. the nature of the onset of the problem). This would have potentially identified the patients with financial compensation to the assessing doctors. Secondly, I am puzzled by the group whose data were excluded from the study. It is reported that 19 patients failed to provide adequate information about their compensation status, and no information concerning their pain and disability scores is provided. However, clinical information was clearly collected on these patients, so that we are told how many of these patients had paresis and how many had undergone surgery. Why was their questionnaire data not obtained or checked when this clinical information was collected?
The inclusion criteria for the study state that patients had to have had their pain for between 4 weeks and 6 months. Therefore, this information must have been collected. However, there is no information provided about the duration of pain in each of the two groups. Indeed, it is mentioned in the discussion that this may be an important confounder. Moreover, because the longer patients have their pain the longer it is likely to persist, this would be an important potential confounder if there were a difference. Furthermore, it may be that compensible patients had sought compensation because of longer duration of their symptoms, which they had expected to improve spontaneously.
The comparison of the groups at baseline cannot exclude an important difference in pain levels between the groups. The numbers are too small, and failing to find a statistically significant difference between small numbers of patients does not exclude a clinically significant difference. In particular, I note that the median disability index in the compensible group was 68, compared with 50 in the non-compensible group. At first glance this would seem an important difference, and failing to reach a statistically significant difference with such small numbers does not eliminate this impression. I am further puzzled by the inclusion in the non-compensible group of at least one patient who scored their pain in the neck as zero (Table 1 in reference [1]). Surely if they have no pain, they should not be in the study, and any improvement or satisfaction is spurious. The inclusion of such patients would undoubtedly bias the study against the compensible group.
I am concerned that only some of the outcome data have been presented. There is no comparison of the two groups' disability scores, pain scores or analgesic use. Rather, we are given global patient perceptions on a non-validated perception scale. I have no doubt that people feel generally worse when their credibility is being questioned or their financial future is at stake, which are both almost invariable consequences of involvement in financial compensation. To present only self-perception measured by a postal questionnaire risks measuring parameters that are unrelated to the study question.
Finally, the literature quoted in the review is a biased cross-section of the available literature of the topic and is accepted uncritically. The conclusions of the study by Cassidy et al. [2], in particular, have been held up to much criticism, as it measures insurance claims and not patient-based data. The authors have not considered, for example, the findings of Swartzman et al. [3].
I would think that a much more robust study is needed to address this difficult and controversial issue successfully.
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