Table 3.

Pain intensity and activity interference at baseline and 4 months later, and estimated effects of opioid use prior to the 4-month assessment on 4-month pain intensity and activity interference (N = 1,311)

Pain intensity					Activity interference
Opioid use, 120-day period prior to 4-mo interview	Pain intensity, baseline Adjusted M (95% CI)	Pain intensity, 4 mo Adjusted M (95% CI)	Estimated effect of opioid use (95% CI)*	P-value**	Activity interference, baseline Adjusted M (95% CI)	Activity interference, 4 mo Adjusted M (95% CI)	Estimated effect of opioid use (95% CI)*	P-value**
Minimal/no	5.82 (5.62, 6.03)	4.94 (4.71, 5.17)	Ref	<0.001	5.57 (5.25, 5.88)	3.92 (3.59, 4.25)	Ref	<0.001
Intermittent/lower-dose	6.03 (5.82, 6.24)	5.97 (5.78, 6.16)	1.03 (0.82, 1.24)		5.38 (5.07, 5.70)	5.08 (4.76, 5.41)	1.16 (0.85, 1.47)
Regular/higher-dose	6.14 (5.94, 6.35)	5.87 (5.67, 6.08)	0.94 (0.72, 1.15)		5.52 (5.21, 5.83)	5.08 (4.77, 5.39)	1.16 (0.85, 1.46)

Ref, reference group

^*Difference in the means between each opioid use group and the reference opioid use group (minimal/no use). The P-value for a two-sided t-test of the difference of the estimated effect (coefficient) from zero was <0.001 for each estimated effect shown in the table.

^**P-value for Wald test of any significant difference among the opioid use categories.

Note: Estimated effects of opioid use were obtained from regression models that were adjusted for age; gender; and baseline disability status (permanently/temporarily disabled or not); confirmed opioid initiator status (yes, no); number of pain days in the past 6 mo; widespread pain bothersomeness; GAD-2; PHQ-8; pain intensity; and activity interference. The baseline mean pain intensity and activity interference scores shown in the table were adjusted for all of these variables except baseline pain intensity or activity interference, respectively. The 4-mo mean pain intensity and activity interference scores shown were adjusted for all of these variables.