Page 157 - THE PERCEPT STUDY Illness Perceptions in Physiotherapy Edwin de Raaij

port the method on how they achieved this reduction6. So, it is difficult to judge if the reduc- tion was done in a valid way so that indeed each single question correctly represents one IP-dimension. An adapted version of the Brief IPQ-DLV will not overcome this issue. A way to overcome Concerns around the content validity would be to evaluate the Revised IPQ with methods of factor analysis. Hereby, all of the questions of the Revised IPQ which are part of the same IP-dimension can be loaded onto this one dimension and the question with the highest factor loading could be chosen as the most representative question of that specific IP-dimension. In addition, a think aloud study would be a next step in order to assess the content validity.
Further, the content validity of the Brief IPQ-DLV can evaluated by using the recommended item from the COSMIN risk of bias list box 2; asking patients and professionals about rele- vance and comprehensiveness and Coherence 32,36, 26.
A final recommendation we would like to make regarding further research is that the respon- siveness needs to be studied as no study has been done yet that addressed the responsive- ness of the Brief IPQ-DLV. Responsiveness, also known as longitudinal validity, is the ability to measure changes that are clinically important. For instance, it is an important measurement property, not only in daily practice to measure a patients’ relevant improvement or decline, but also an important measurement property to be used in intervention studies to assess the effectiveness of interventions on IPs. Therefore, we recommend further research on the longitudinal validity of the Brief IPQ-DLV. This will reveal how to interpret change scores.
Practical implications
To overcome the above addressed problem and still find a meaningful way of using the Brief IPQ-DLV in daily practice we recommend using qualitative interview techniques in combina- tion with the Brief IPQ-DLV. This means, that after a patient has filled out the Brief IPQ-DLV a physiotherapist can interview the patient for a more in depth understanding on the meaning of scores from the Brief IPQ-DLV means. For instance, by using a Socratic style of dialog as used in the study by Siemonsma et al. 34.
For example, suppose a patient with persistent low back pain scores 8 (0-10, higher score means a better understanding) on the ‘How do you feel you understand your illness? ‘. This does not necessarily mean this perception is functional for this individual. A score on the Brief IPQ-DLV does not tell you what this patient exactly understands, it could be that he or she thinks that their lower back vertebras are out of position and needs re-adjustment. Although this perception might be considered as dysfunctional, we only can explore this perception in more depth by interviewing this patient after completion of the questionnaire, using the
General discussion
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