Page 134 - THE PERCEPT STUDY Illness Perceptions in Physiotherapy Edwin de Raaij

Chapter 7
Table 5 shows the results of the linear mixed model analyses to investigate whether prima- ry outcomes changed during and after matched-care physiotherapy. During treatment, all three outcomes show a significant and clinical meaningful improvement of ≥ 30% effect. The adjusted effects shows clinical meaningful improvement of ≥ 30% for pain and physical functioning. Post treatment, the effect did not wash-out. Remaining in significant and clinical meaningful improvement of ≥ 30% for all three outcomes.
Table 5: Final linear mixed model Regression effects, study phase A as reference class
During treatment
Post treatment
Effect crude Mean
95% CI
Effect adjusted*
95% CI
Effect crude Mean
95% CI
Effect adjusted*
95% CI
PI
range 0-10
-2.2^
-2.9, -1.5
-1.3
-1.9, -0.7
-3.5^
-4.2, -2.8
-1.8^
-2.4, -1.2
PF
range 0-10
-2.4^
-3.1, -1.8
-1.6^
-2.2, -1.1
-4.1^
-4.5, -3.4
-2.6^
-3.2, -1.1
PIDL range 0-10
-2.4^
-3.1, -1.7
-1.3
-1.9, 0.7
-4.2^
-4.9, -3.6
-2.4^
-3.0, -1.8
PI = Pain Intensity, PF = Physical Functioning, PIDL = Pain Interference in Daily Life, All outcome = P <.05, ^ = Clinical meaningful improvement ≥ 30% baseline score29,*adjusted for: fear of movement, catastrophizing, avoidance, somberness and sleep
Table 6 shows the results of the mediation analyses performed on the adjusted models. Five of the 8 IP dimensions substantially mediated the total effect on all three primary out- comes. For instance, the IP dimension Consequences mediated for 38.5% the effect of the treatment on pain intensity during the treatment (Phase B) and this increased to 38.9% for the post-treatment (Phase A’). The IP Consequences and Identity were strong mediators in all three primary outcomes. The other dimensions that mediated the effect of the treatment on the outcome were Identity, Concern, Emotional and Personal control. Three IPs showed lesser mediation effects, with Timeline being the smallest mediator by 1.7% for Physical functioning post treatment.
Table 7 shows the statistically significant results of the moderation analyses performed on the adjusted models. The IPs dimension Personal control moderated the treatment effects for all three primary outcomes. There is a stronger treatment effect for patients with a low baseline score (0-7) on Personal control versus patients with high baseline scores (8-10) on Personal control. This means that when patients experienced higher control (0-7) over their condition at baseline, the stronger the positive effect on the primary outcome was in both the treatment and the post-treatment phases.
The IPs dimension Treatment control showed a moderating effect for Physical functioning. This indicates a stronger treatment effect for patients with a low baseline score (0-4) on
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