Table 2.

Predictors of percent reduction in Brief Pain Inventory (BPI) severity at Week 8–multivariate regression analysis*

	Coefficient	95% CI	P
Treatment (Sham acupuncture as reference)	114.3	−11.8 to 240.4	.074
Baseline expectancy score†	7.9	2.3 to 13.5	.007
Treatment × baseline expectancy score‡	−8.3	−16.8 to 0.2	.056
Constants	−67.6	−147.9 to 12.6	.096

* CI = confidence interval.

† Expectancy measured by the Acupuncture Expectancy Scale.

‡ When interaction occurs, the individual term cannot be interpreted by itself. The individual term and the interaction term should be combined in explaining the dependent variable.