Table 4. Secondary outcomes.

	Observed unadjusted mean (SD)						Slope (95% CI)	Adjusted Mean difference (95% CI)
	Oregon	Minnesota	SMT 0	SMT 6	SMT 12	SMT 18	Per 6 SMT sessions	SMT 0 vs SMT 6	SMT 0 vs SMT 12	SMT 0 vs SMT 18
CGH pain intensity averaged over days with CGH in last 4 wk (0–10 scale)†					Anchors: “No pain” (0); “ As bad as pain could be” (10).
0 wk	4.5 (1.1)	4.5 (1.1)	4.4 (1.0)	4.4 (1.0)	4.5 (1.1)	4.7 (1.1)
6 wk	3.9 (1.3)	3.9 (1.2)	4.1 (1.2)	3.9 (1.2)	3.8 (1.4)	3.8 (1.2)	-0.1 (-0.2, -0.0)*	-0.3 (-0.7, 0.0)	-0.2 (-0.6, 0.1)	-0.5 (-0.8, -0.1)*
12 wk	4.0 (1.5)	4.0 (1.3)	4.2 (1.4)	4.0 (1.4)	3.8 (1.4)	4.1 (1.5)	-0.1 (-0.2, 0.0)	-0.3 (-0.7, 0.1)	-0.4 (-0.8, 0.1)	-0.3 (-0.8, 0.1)
24 wk	4.1 (1.5)	3.9 (1.2)	4.3 (1.5)	3.8 (1.2)	3.8 (1.3)	4.1 (1.5)	-0.1 (-0.2, 0.1)	-0.5 (-0.9, -0.1)	-0.3 (-0.7, 0.1)	-0.3 (-0.7, 0.1)
39 wk	4.1 (1.6)	4.0 (1.3)	4.1 (1.4)	4.1 (1.4)	4.0 (1.5)	4.1 (1.4)	-0.1 (-0.2, 0.1)	-0.2 (-0.6, 0.2)	-0.1 (-0.5, 0.4)	-0.3 (-0.8, 0.1)
52 wk	4.0 (1.6)	4.0 (1.3)	4.1 (1.3)	4.1 (1.3)	3.8 (1.5)	4.0 (1.5)	-0.1 (-0.3, 0.0)	-0.2 (-0.6, 0.2)	-0.3 (-0.7, 0.2)	-0.4 (-0.9, 0.0)
6 to 52 wk							-0.1 (-0.2, -0.0)*	-0.3 (-0.6, 0.0)	-0.2 (-0.6, 0.1)	-0.4 (-0.7, -0.0)*
CGH-related disability (36–78 scale)†
0 wk	58.7 (4.6)	56.1 (4.9)	58.5 (4.6)	56.0 (5.2)	57.2 (5.1)	57.9 (4.4)
6 wk	52.4 (6.5)	51.2 (6.2)	54.1 (5.9)	52.1 (5.8)	49.7 (7.0)	51.3 (6.1)	-1.3 (-2.0, -0.6)*	-2.4 (-4.6, -0.3)*	-4.5 (-6.7, -2.3)*	-3.6 (-5.8, -1.4)*
12 wk	52.7 (6.7)	50.1 (6.6)	54.0 (6.5)	51.5 (6.2)	49.4 (6.8)	50.3 (6.9)	-1.4 (-2.1, -0.7)*	-2.1 (-4.3, 0.1)	-4.4 (-6.6, -2.2)*	-3.8 (-6.0, -1.5)*
24 wk	52.2 (7.6)	50.4 (6.7)	52.6 (5.9)	50.4 (7.1)	51.4 (7.6)	50.4 (7.8)	-0.9 (-1.7, -0.1)*	-2.4 (-4.8, -0.1)*	-2.2 (-4.6, 0.2)	-3.1 (-5.5, -0.7)*
39 wk	52.5 (7.8)	50.8 (7.3)	53.8 (6.4)	51.1 (7.1)	51.0 (8.3)	50.6 (8.1)	-1.0 (-1.9, -0.2)*	-2.3 (-4.8, 0.2)	-2.8 (-5.4, -0.3)*	-3.3 (-5.9, -0.7)*
52 wk	52.5 (7.6)	50.3 (7.2)	53.4 (6.7)	51.1 (6.6)	50.6 (7.9)	50.3 (8.1)	-1.1 (-1.9, -0.3)*	-2.0 (-4.4, 0.5)	-3.0 (-5.4, -0.5)*	-3.4 (-5.9, -0.9)*
6 to 52 wk							-1.1 (-1.8, -0.5)*	-2.3 (-4.1, -0.4)*	-3.4 (-5.3, -1.4)*	-3.4 (-5.3, -1.5)*
Perceived CGH pain change since baseline (-10–10 scale)†					Anchors: “Pain has decreased” (-10 to -1); “No change” (0); “Pain has increased” (1 to 10).
6 wk	-3.6 (3.0)	-2.7 (2.9)	-2.1 (2.9)	-2.6 (2.6)	-3.6 (2.7)	-4.1 (3.2)	-0.7 (-1.0, -0.3)*	-0.5 (-1.5, 0.5)	-1.6 (-2.6, -0.5)*	-1.8 (-2.9, -0.8)*
12 wk	-3.2 (2.9)	-2.6 (2.9)	-1.4 (2.5)	-2.8 (2.7)	-3.5 (3.1)	-3.6 (2.9)	-0.6 (-0.9, -0.3)*	-1.1 (-2.1, -0.1)*	-2.1 (-3.1, -1.1)*	-1.8 (-2.8, -0.7)*
24 wk	-2.5 (3.0)	-2.8 (3.2)	-1.8 (2.8)	-1.8 (2.6)	-3.2 (3.3)	-3.8 (3.5)	-0.6 (-0.9, -0.2)*	0.3 (-0.8, 1.3)	-1.3 (-2.3, -0.2)*	-1.4 (-2.5, -0.3)*
39 wk	-2.7 (3.5)	-2.5 (3.4)	-1.5 (3.0)	-2.5 (3.5)	-3.2 (3.3)	-3.2 (3.6)	-0.4 (-0.8, -0.0)*	-0.3 (-1.5, 0.9)	-1.4 (-2.6, -0.2)*	-1.0 (-2.2, 0.3)
52 wk	-2.9 (3.5)	-3.1 (3.6)	-2.1 (3.3)	-2.2 (3.3)	-3.6 (3.8)	-4.0 (3.5)	-0.6 (-1.0, -0.2)*	0.4 (-0.9, 1.6)	-1.4 (-2.6, -0.1)*	-1.4 (-2.7, -0.2)*
6 to 52 wk							-0.6 (-0.8, -0.3)*	-0.2 (-1.1, 0.6)	-1.5 (-2.4, -0.7)*	-1.5 (-2.4, -0.6)*
					Anchors: “No symptoms” (1); “Much better” (2); “Somewhat better” (3); “A little better”(4); No change” (5);
Perceived CGH global improvement since baseline (1–9 scale)†					“A little worse” (6); “Somewhat worse” (7);“Much worse” (8); ”As bad as it could be” (9).
6 wk	3.1 (1.3)	3.5 (1.2)	4.0 (1.2)	3.6 (1.2)	2.9 (1.0)	2.9 (1.2)	-0.4 (-0.5, -0.3)*	-0.4 (-0.8, 0.0)	-1.1 (-1.6, -0.7)*	-1.1 (-1.5, -0.7)*
12 wk	3.2 (1.2)	3.5 (1.3)	4.1 (1.1)	3.4 (1.1)	3.0 (1.2)	3.0 (1.2)	-0.4 (-0.5, -0.2)*	-0.6 (-1.0, -0.2)*	-1.2 (-1.6, -0.8)*	-1.0 (-1.4, -0.6)*
24 wk	3.4 (1.2)	3.5 (1.4)	3.9 (1.3)	3.7 (1.2)	3.2 (1.3)	3.0 (1.1)	-0.3 (-0.4, -0.2)*	-0.1 (-0.5, 0.3)	-0.7 (-1.2, -0.3)*	-0.8 (-1.3, -0.4)*
39 wk	3.4 (1.4)	3.6 (1.3)	4.1 (1.2)	3.7 (1.3)	3.1 (1.3)	3.2 (1.4)	-0.3 (-0.5, -0.2)*	-0.2 (-0.7, 0.2)	-0.9 (-1.4, -0.4)*	-0.8 (-1.3, -0.3)*
52 wk	3.5 (1.3)	3.5 (1.4)	3.9 (1.3)	3.8 (1.3)	3.1 (1.2)	3.2 (1.3)	-0.3 (-0.4, -0.1)*	0.0 (-0.5, 0.5)	-0.8 (-1.3, -0.3)*	-0.7 (-1.1, -0.2)*
6 to 52 wk							-0.3 (-0.4, -0.2)*	-0.3 (-0.6, 0.1)	-0.9 (-1.3, -0.6)*	-0.9 (-1.2, -0.5)*
					Anchors: “Extremely doubtful” (1); “Doubtful” (2); “A little doubtful” (3); “Unsure” (4);
Confidence care is working (1–7 scale)‡					“A little certain” (5); “Certain” (6); “Extremely certain” (7).
6 wk	5.1 (1.7)	4.8 (1.8)	3.8 (2.0)	4.7 (1.6)	5.8 (1.0)	5.4 (1.6)	0.6 (0.4, 0.8)*	0.9 (0.3, 1.4)*	2.0 (1.4, 2.6)*	1.6 (1.0, 2.2)*
12 wk	5.0 (1.7)	4.7 (1.6)	3.8 (1.8)	4.7 (1.4)	5.6 (1.2)	5.3 (1.7)	0.5 (0.3, 0.7)*	0.7 (0.1, 1.2)*	1.8 (1.2, 2.3)*	1.3 (0.8, 1.9)*
24 wk	4.7 (1.6)	4.7 (1.7)	4.0 (1.8)	4.4 (1.6)	5.3 (1.4)	5.2 (1.5)	0.4 (0.2, 0.6)*	0.2 (-0.4, 0.7)	1.3 (0.7, 1.9)*	1.0 (0.4, 1.5)*
39 wk	4.8 (1.6)	4.6 (1.7)	3.8 (2.0)	4.6 (1.4)	5.2 (1.4)	5.1 (1.6)	0.4 (0.2, 0.6)*	0.6 (0.1, 1.2)*	1.3 (0.8, 1.9)*	1.1 (0.5, 1.6)*
52 wk	4.6 (1.7)	4.6 (1.7)	3.6 (1.9)	4.3 (1.6)	5.2 (1.4)	5.1 (1.6)	0.5 (0.3, 0.7)*	0.6 (-0.0, 1.1)	1.6 (1.0, 2.1)*	1.3 (0.7, 1.9)*
6 to 52 wk							0.5 (0.3, 0.6)*	0.6 (0.1, 1.1)*	1.6 (1.1, 2.1)*	1.3 (0.7, 1.8)*
					Anchors: “Extremely dissatisfied” (1); “Dissatisfied” (2); “Somewhat dissatisfied” (3);
Satisfaction with care (1–6 scale)‡					“Some what satisfied”(4); “Satisfied” (5); “Extremely satisfied” (6).
6 wk	4.9 (1.2)	5.0 (1.1)	4.3 (1.4)	4.7 (1.2)	5.4 (0.7)	5.3 (1.0)	0.3 (0.2, 0.5)*	0.4 (0.0, 0.8)*	1.1 (0.7, 1.5)*	0.9 (0.6, 1.3)*
12 wk	4.8 (1.3)	4.9 (1.1)	4.2 (1.4)	4.8 (1.2)	5.4 (0.7)	5.2 (1.0)	0.3 (0.2, 0.5)*	0.5 (0.1, 0.9)*	1.1 (0.7, 1.5)*	0.9 (0.5, 1.3)*
24 wk	4.7 (1.3)	4.9 (1.1)	4.2 (1.4)	4.7 (1.2)	5.3 (0.8)	5.2 (0.9)	0.4 (0.2, 0.5)*	0.5 (0.1, 0.9)*	1.1 (0.7, 1.6)*	1.0 (0.5, 1.4)*
39 wk	4.7 (1.3)	4.8 (1.2)	4.1 (1.5)	4.5 (1.2)	5.2 (0.8)	5.0 (1.1)	0.3 (0.2, 0.4)*	0.3 (-0.1, 0.8)	1.1 (0.6, 1.5)*	0.7 (0.3, 1.2)*
52 wk	4.7 (1.3)	4.8 (1.2)	4.1 (1.5)	4.6 (1.1)	5.2 (0.8)	5.1 (1.1)	0.3 (0.2, 0.5)*	0.4 (0.0, 0.8)*	1.1 (0.7, 1.5)*	0.9 (0.5, 1.3)*
6 to 52 wk							0.3 (0.2, 0.5)*	0.4 (0.0, 0.8)*	1.1 (0.8, 1.5)*	0.9 (0.5, 1.3)*
Would seek same therapy in the future (1-5 scale)‡					Anchors: “Strongly disagree” (1); “Strongly agree” (5).
6 wk	3.7 (1.4)	3.5 (1.3)	2.6 (1.6)	3.5 (1.2)	4.2 (1.0)	4.1 (1.1)	0.5 (0.3, 0.6)*	0.9 (0.5, 1.4)*	1.6 (1.1, 2.0)*	1.4 (1.0, 1.9)*
12 wk	3.7 (1.5)	3.6 (1.3)	2.6 (1.5)	3.7 (1.3)	4.3 (1.0)	4.1 (1.2)	0.5 (0.3, 0.6)*	1.0 (0.5, 1.4)*	1.7 (1.3, 2.2)*	1.3 (0.9, 1.8)*
24 wk	3.7 (1.4)	3.5 (1.4)	2.7 (1.4)	3.4 (1.4)	4.2 (1.0)	4.1 (1.2)	0.5 (0.3, 0.6)*	0.6 (0.2, 1.1)*	1.5 (1.1, 2.0)*	1.3 (0.9, 1.8)*
39 wk	3.7 (1.4)	3.5 (1.4)	2.6 (1.5)	3.6 (1.4)	4.2 (1.0)	4.1 (1.2)	0.5 (0.3, 0.6)*	0.9 (0.4, 1.3)*	1.6 (1.1, 2.0)*	1.3 (0.9, 1.8)*
52 wk	3.7 (1.5)	3.5 (1.4)	2.5 (1.6)	3.5 (1.3)	4.2 (1.1)	4.0 (1.2)	0.5 (0.4, 0.7)*	0.9 (0.5, 1.4)*	1.7 (1.3, 2.2)*	1.5 (1.0, 1.9)*
6 to 52 wk							0.5 (0.3, 0.6)*	0.9 (0.4, 1.3)*	1.6 (1.2, 2.0)*	1.4 (0.9, 1.8)*
Days with non-CGH headaches (last 4 wk)†
0 wk	2.3 (2.7)	2.3 (3.0)	2.3 (3.1)	2.4 (3.0)	2.3 (2.4)	2.2 (3.1)
6 wk	2.2 (3.0	1.9 (2.8)	2.4 (2.9)	2.3 (3.1)	1.7 (2.5)	2.0 (3.7)	-0.1 (-0.5, 0.2)	-0.2 (-1.2, 0.9)	-0.5 (-1.6, 0.6)	-0.4 (-1.4, 0.6)
12 wk	2.1 (3.6)	1.8 (2.8)	1.8 (3.0)	2.3 (2.9)	1.6 (2.1)	2.1 (4.5)	0.1 (-0.2, 0.5)	0.5 (-0.6, 1.6)	0.1 (-1.0, 1.2)	0.6 (-0.5, 1.7)
24 wk	2.3 (3.6)	1.9 (3.4)	1.6 (2.7)	2.4 (3.0)	2.3 (3.3)	1.8 (4.5)	-0.0 (-0.4, 0.4)	0.5 (-0.7, 1.7)	0.7 (-0.5, 1.9)	-0.1 (-1.3, 1.1)
39 wk	1.9 (2.8)	1.9 (3.5)	1.6 (1.9)	2.3 (4.0)	1.7 (2.4)	1.9 (3.7)	-0.0 (-0.4, 0.4)	0.4 (-0.7, 1.6)	0.2 (-0.9, 1.3)	0.1 (-1.1, 1.2)
52 wk	2.1 (3.5)	1.7 (3.5)	1.4 (1.8)	2.0 (3.3)	1.5 (2.7)	2.5 (5.1)	0.2 (-0.2, 0.6)	0.3 (-0.9, 1.5)	0.2 (-1.0, 1.4)	0.8 (-0.4, 2.0)
6 to 52 wk							0.0 (-0.3, 0.4)	0.3 (-0.5, 1.1)	0.1 (-0.7, 1.0)	0.2 (-0.9, 1.3)
Days with neck pain (last 4 wk)†
0 wk	18.8 (7.2)	17.9 (7.8)	19.2 (7.6)	18.8 (7.2)	18.2 (8.0)	17.1 (7.3)
6 wk	14.1 (9.0)	14.0 (8.7)	16.8 (9.0)	14.7 (8.4)	12.3 (8.4)	12.3 (9.0)	-1.7 (-2.5, -0.9)*	-2.0 (-4.5, 0.6)	-4.8 (-7.4, -2.2)*	-4.7 (-7.3, -2.1)*
12 wk	13.2 (9.0)	11.7 (9.1)	15.2 (9.6)	13.5 (8.6)	12.2 (8.8)	8.7 (8.1)	-2.0 (-2.9, -1.2)*	-1.4 (-4.1, 1.3)	-3.4 (-6.1, -0.7)*	-6.2 (-8.9, -3.4)*
24 wk	13.3 (9.6)	12.2 (9.4)	13.4 (9.4)	14.4 (9.6)	12.6 (9.8)	10.4 (9.0)	-1.4 (-2.3, -0.4)*	0.7 (-2.2, 3.6)	-2.1 (-5.0, 0.8)	-3.7 (-6.6, -0.7)*
39 wk	12.1 (9.3)	11.1 (9.3)	12.9 (10.1)	12.4 (9.5)	11.1 (8.8)	10.0 (8.8)	-1.0 (-2.0, -0.1)*	-0.3 (-3.2, 2.6)	-2.0 (-4.9, 1.0)	-2.9 (-5.8, 0.1)
52 wk	12.0 (9.9)	11.3 (9.3)	13.1 (9.6)	12.3 (9.9)	11.2 (9.7)	10.1 (9.2)	-1.1 (-2.0, -0.1)*	-0.4 (-3.3, 2.6)	-2.2 (-5.2, 0.8)	-2.9 (-5.9, 0.0)
6 to 52 wk							-1.4 (-2.2, -0.7)*	-0.7 (-2.9, 1.6)	-2.9 (-5.2, -0.6)*	-4.1 (-6.4, -1.8)*
Average neck pain intensity in last 4 wk (0–10 scale)†					Anchors: “No pain” (0); “As bad as pain could be” (10).
0 wk	4.6 (1.5)	4.6 (1.5)	4.5 (1.5)	4.5 (1.4)	4.5 (1.5)	4.8 (1.5)
6 wk	3.5 (1.6)	3.9 (1.8)	4.1 (1.7)	3.9 (1.4)	3.2 (1.8)	3.7 (1.8)	-0.2 (-0.4, -0.1)*	-0.3 (-0.9, 0.2)	-0.8 (-1.3, -0.2)*	-0.7 (-1.2, -0.1)*
12 wk	3.7 (1.7)	3.6 (1.8)	4.0 (1.8)	3.7 (1.4)	3.4 (1.8)	3.5 (1.9)	-0.2 (-0.4, -0.1)*	-0.3 (-0.9, 0.2)	-0.6 (-1.2, -0.1)*	-0.7 (-1.2, -0.1)*
24 wk	3.7 (1.9)	3.8 (1.8)	3.9 (1.7)	3.9 (1.9)	3.6 (1.9)	3.7 (2.0)	-0.2 (-0.3, 0.0)	-0.1 (-0.7, 0.5)	-0.5 (-1.1, 0.1)	-0.4 (-1.0, 0.2)
39 wk	3.8 (1.9)	3.7 (1.9)	3.9 (1.8)	4.0 (1.9)	3.5 (2.0)	3.6 (1.9)	-0.2 (-0.4, 0.0)	0.1 (-0.5, 0.6)	-0.4 (-1.0, 0.1)	-0.4 (-1.0, 0.2)
52 wk	3.6 (2.1)	3.5 (1.8)	3.8 (1.9)	3.5 (1.8)	3.2 (2.0)	3.7 (2.1)	-0.1 (-0.3, 0.1)	-0.3 (-0.9, 0.3)	-0.7 (-1.3, -0.1)*	-0.3 (-0.9, 0.3)
6 to 52 wk							-0.2 (-0.3, -0.1)*	-0.2 (-0.6, 0.2)	-0.6 (-1.0, -0.2)*	-0.5 (-0.9, -0.1)*
EuroQol “Health State Today” (0–100 visual analog scale)‡					Anchors: “worst imaginable health state” (0); “best imaginable health state” (100).
0 wk	74.4 (13.7)	76.7 (13.2)	74.9 (13.7)	76.3 (11.3)	76.1 (13.9)	74.8 (15.0)
12 wk	77.1 (11.4)	80.6 (12.1)	78.2 (11.2)	77.8 (14.0)	81.5 (9.4)	78.4 (12.1)	1 (-1, 2)	-2 (-6, 2)	2 (-3, 6)	1 (-4, 5)
24 wk	77.7 (12.4)	80.8 (11.7)	78.5 (12.3)	81.3 (10.5)	80.2 (11.0)	77.6 (14.3)	0 (-1, 2)	2 (-2, 7)	2 (-3, 6)	0 (-4, 5)
39 wk	77.0 (12.9)	81.3 (11.3)	76.7 (13.3)	79.9 (10.1)	81.0 (12.2)	79.8 (12.9)	1 (-0, 3)	2 (-2, 7)	3 (-2, 7)	3 (-1, 8)
52 wk	77.1 (13.7)	81.2 (12.8)	76.1 (15.6)	79.5 (12.3)	81.2 (13.1)	80.2 (12.2)	1 (-0, 3)	2 (-3, 7)	4 (-1, 9)	4 (-1, 9)
6 to 52 wk							1 (-0, 2)	1 (-3, 5)	2 (-2, 6)	2 (-2, 6)
Days taking medication for CGH (last 4 wk)†
0 wk	6.3 (4.9)	6.3 (4.6)	5.6 (4.5)	5.9 (4.0)	6.6 (5.4)	7.0 (4.8)
6 wk	4.6 (4.1)	4.4 (4.6)	4.8 (4.9)	4.5 (4.0)	4.5 (4.4)	4.3 (4.2)	-0.3 (-0.7, 0.2)	-0.3 (-1.8, 1.2)	-0.6 (-2.2, 0.9)	-0.7 (-2.3, 0.8)
12 wk	4.1 (5.0)	4.0 (4.0)	4.2 (4.0)	4.2 (4.6)	4.1 (5.3)	3.7 (3.9)	-0.3 (-0.8, 0.2)	-0.1 (-1.6, 1.5)	-0.6 (-2.1, 1.0)	-0.9 (-2.5, 0.7)
24 wk	4.4 (4.8)	3.6 (3.6)	4.1 (3.4)	3.9 (4.3)	3.8 (4.6)	4.0 (4.3)	-0.2 (-0.7, 0.3)	-0.4 (-2.0, 1.1)	-1.0 (-2.5, 0.5)	-0.5 (-2.1, 1.0)
39 wk	3.6 (4.5)	3.7 (4.2)	3.0 (3.2)	3.8 (3.9)	3.8 (5.2)	4.0 (4.8)	0.0 (-0.5, 0.5)	0.3 (-1.3, 1.9)	0.1 (-1.6, 1.7)	0.1 (-1.5, 1.7)
52 wk	3.8 (4.6)	4.1 (4.4)	3.9 (3.8)	4.5 (4.7)	3.9 (5.4)	3.5 (3.9)	-0.3 (-0.8, 0.2)	0.2 (-1.4, 1.8)	-0.4 (-2.1, 1.2)	-0.8 (-2.5, 0.8)
6 to 52 wk							-0.2 (-0.6, 0.2)	-0.1 (-1.3, 1.2)	-0.5 (-1.9, 0.9)	-0.6 (-1.8, 0.7)

SD, standard deviation; CI, confidence interval; UWS, University of Western States; NWHSU, Northwestern Health Sciences University; SMT, spinal manipulation; CGH, cervicogenic headache; VAS, visual analog scale.

Unadjusted means are from original data without imputation; slopes and mean differences are computed from imputed data and adjusted for baseline covariates. Longitudinal profiles using generalized estimating equations are indicated by lines labeled “6 to 52” weeks.

^*p<.05.

^†Lower scores are favorable; negative signs of slopes and risk differences favor higher doses of manipulation.

^‡Higher scores are favorable; positive signs of slopes and risk differences favor higher doses of manipulation.