Appendix 4.

Multilevel analysis with the square root of consultations during the post-intervention year as the dependent variable, without imputed data (model 1), and with imputed data and intention-to-treat (model 2).

Multilevel model	Model 1 (n = 166)			Model 2 (n =209)
Variables	Beta	SE (beta)	P-value	Beta	SE (beta)	P-value
Timea	−1.0625	0.1015	<0.001	−0.9814	0.1394	<0.001
Group Ab	−0.4511	0.1746	0.010	−0.1377	0.1459	0.345
Group Bc	−0.1185	0.2542	0.641	−0.0072	0.1802	0.968
Interaction between time and group A	0.9788	0.1421	<0.001	0.5210	0.1776	0.003
Interaction between time and group B	1.3421	0.1464	<0.001	0.8708	0.1916	<0.001
Age	0.0308	0.0047	<0.001	0.0375	0.0037	<0.001
Trait anxiety (STAI-T)	0.0059	0.0068	0.386	0.0078	0.0055	0.158
Satisfaction with GP (group A)	−0.2353	0.1817	0.195	−0.1260	0.1458	0.388
Satisfaction with GP (group B)	0.0004	0.1788	0.998	0.0277	0.1474	0.851
Logarithm of number of chronic diseases	0.4615	0.1543	0.003	0.2890	0.1250	0.021
Hypochondria (GH+WI)	0.0439	0.0207	0.034	0.0205	0.0156	0.190
Random-effects parameters
Doctor	0.2060	0.0999		0.1055	0.0874
Patient	0.7235	0.0531		0.5150	0.0644
Residual	0.5275	0.0295		0.6875	0.0422

^aTime = observation time (baseline and 1 year post-intervention).

^bGroup A = contrast between intervention group and control group 1.

^cGroup B = contrast between intervention group and control group 2. SE: standard error. STAI = State–Trait Anxiety Inventory.²³ GH+WI = General Hypochondria and Witheley Index from the Illness Behaviour Questionnaire.²⁶