Table 3.

Characteristics and parameter estimates of the regression equations for each pain severity trajectory.

			Slopes		Predicted values
Trajectory	n	Intercept	Linear	Quadratic	Baseline	6 Months	12 Months	24 Months
1 (Non-improvers)	1430	0a	−0.05**	0.001	0	−0.25	−0.44	−0.59
2 (Steady improvers)	313	−2.30**	−0.19**	0.004*	−2.30	−3.30	−4.00	−4.54
3 (Early improvers)	151	−0.83*	−0.89**	0.031**	−0.83	−5.06	−7.06	−4.33

^aIntercept for first trajectory set at 0.

*P < 0.05. **P < 0.01.