Table 4.

Predictors of Treatment Effect

Subgroups	N	Predicted Mean Difference in RMDQ Between Treatment Groups (95% CI)	P-value	Interaction Between Treatment and Subgroup (95% CI)	P-value
Overall	78	−1.4 (−3.7 to 1.0)	0.25	–	–
Analysis 2 (subgroups based on cluster analysis)
Cluster category 3+4	41	−2.0 (−5.2 to 1.3)	0.23	–	–
Cluster category 1+2	37	−0.5 (−3.9 to 2.9)	0.77	1.4 (−3.2 to 6.1)	0.54
Analyses 3 (subgroups based on PCA)
Principal component 1 (analysis 3A)	78	–	–	−0.1 (−1.0 to 1.1)	0.89
Principal component 1 (analysis 3B)	78	–	–	0.0 (−0.8 to 0.8)	0.97

Notes: Predicted mean difference in RMDQ between amoxicillin and placebo groups with 95% CI and estimated effects of interactions terms with 95% CI, both based on linear regression of the intention to treat group. Analyses 1 are omitted as the recursive partitioning analyses did not result in any suggested subgroup to be tested by linear regression analyses.

Abbreviations: N, number of patients included in analysis; RMDQ, Roland–Morris Disability Questionnaire (measure of physical function), score 0–24; PCA, principal component analysis.