Page 103 - THE PERCEPT STUDY Illness Perceptions in Physiotherapy Edwin de Raaij

Discussion
In addition to generic prognostic factors, two of the IP dimensions, Treatment Control and Timeline, give a small added predictive value for poor recovery from MSP in pain intensity, physical functioning and Global Perceived Effect. The Brief IPQ-DLV showed weak correlation with the 4DSQ for all IP dimensions. The highest correlations (0.32 to 0.40) were for the IP dimensions Consequences and Emotional Response. There were no significant differences in the added predictive values for poor recovery between the Brief IPQ-DLV and the 4DSQ.
Added predictive value of illness perceptions
Most IPs did not add predictive value for poor recovery. The amount of explained variance in Block 1 increased when adding Block 2 (Table 5) but the increase was small and most of the variance remained unexplained. This is also seen in the increase of the AUC from Step 1 to 2 by just 2-3 percent. Furthermore, from our data a higher score on Treatment Control (hypothesized as increasing the chance of poor recovery) showed the opposite. This is not in line with other research in patients attending a general physician, an inpatient rehabilitation program, or an acupuncturist for low back pain, where reporting higher scores for IPs was predictive of greater limitations in PF with low back pain 15,16,9,5. We researched outpatients receiving usual physiotherapy care for a wide range of MSP, which makes comparison of results difficult. Looking at the difference between good and poor clinical recovery for Treatment Control scores (Table 3) we see very small differences. This means that, although Treatment Control contributes to added predictive value, the clinical importance is limited. In contrast with previous research, we adjusted our findings for known generic prognostic factors and psychological factors.
The IP Timeline (patients’ beliefs about how long their condition will last) is an additional prognostic factor of poor recovery in PF (Table 5). This is in line with published research about recovery expectations, in which Timeline was found to be a factor in general expecta- tions for individual recovery 20.
For interpretation of our findings on the additional predictive value of baseline IPs, the chosen generic prognostic factors must be taken into account. Using other prognostic factors may lead to different outcomes and interpretation of the predictive value of baseline IPs.
Association and difference in predictive value between 4DSQ and Brief IPQ-DLV
The weak associations of the Brief IPQ-DLV with the 4DSQ indicate that they address different constructs. Additionally, both performed equally weakly as predictors for poor recovery in all
A multi-center longitudinal study
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