Table 6.

Stepwise forward multivariate analyses of sociodemographic and disease status variables in relation to GHQ-12 (n = 474).

Step	Predictors	β-Weights	CI (95%)	Standard β-Weights	p	R² (%), p+^*	ΔR² (%), p+^**
1	BASDAI (0–10)	1.912	1.551, 2.274	0.562	< 0.001	0.875	0.875
2	Patient association membership	2.028	1.012, 3.044	0.161	< 0.001	0.883	0.008
3	Functional limitations (0–54)	0.112	0.053, 0.171	0.170	< 0.001	0.888	0.005
4	Cervical stiffness (1–4)	0.610	0.054, 1.166	0.080	0.032	0.889	0.001

Only values that were statistically significant in the bivariate analysis (or marginally significant: p < 0.09) were included in the analysis. All β-weights, 95% CI, and p values for individual variables were estimates derived in the context of the full model (i.e., with all 3 conceptual blocks entered into the equation).
↵* Overall R² (%) after adding each conceptual block and accompanying p value for the test of the overall R².
↵** Incremental R² change due to the addition of the conceptual block and accompanying p value for the test of the incremental R² change. BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; GHQ-12: 12-item General Health Questionnaire.