Table 1 Patient-reported baseline characteristics of chiropractic patients (a) and general practice patients (b)

All chiropractic patients (a)

n = 947

‘LBP alone’

n = 614 (67%)

‘LBP + pain above knee’

n = 219 (24%)

‘LBP + pain below knee’

n = 69 (7%)

‘LBP + signs of nerve root involvement’

n = 20 (2%)

Quebec missing

n = 25 (3%)

p-values^§

Age in years^a

43 (28, 59)

42 (27, 58)

45 (30, 60)

47 (32, 63)

48 (33, 66)

37 (23, 62)

<.01

Females^b

45 (42–48)

42 (38–45)

52 (45–58)

52 (40–64)

55 (32–76)

40 (22–61)

0.03

Physical work load^b

0.82

 - Sitting

23 (21–26)

23 (20–27)

25 (19–31)

22 (13–34)

18 (5–46)

22 (9–45)

 - Sitting/walking

34 (31–37)

34 (30–38)

34 (28–41)

38 (27–52)

41 (19–67)

22 (9–45)

 - Light physical work

21 (19–24)

22 (19–25)

20 (15–26)

17 (9–29)

6 (1–37)

35 (17–57)

 - Heavy physical work

21 (19–24)

21 (18–24)

21 (16–27)

23 (14–36)

35 (15–62)

22 (9–45)

Sick leave^b

22 (19–25)

20 (17–24)

26 (20–32)

28 (18–41)

24 (8–52)

14 (4–37)

0.23

Educational level^b

0.04

 - No qualification

9 (7–11)

9 (7–12)

10 (6–15)

6 (2–16)

11 (2–39)

-

 - Vocational training,

26 (23–29)

26 (23–30)

24 (18–30)

32 (22–45)

33 (14–60)

25 (11–47)

 - Higher education < 3 y

16 (13–18)

14 (12–17)

21 (16–27)

8 (3–18)

28 (11–55)

13 (4–34)

 - Higher education 3–4 y

34 (31–38)

33 (30–37)

36 (31–43)

37 (26–50)

28 (11–55)

42 (23–63)

 - Higher education >4 y

15 (13–18)

17 (14–21)

9 (6–14)

17 (9–28)

-

21 (8–43)

Duration of pain^b

0.02

 - 0–2 weeks

62 (59–66)

66 (62–70)

58 (52–65)

55 (42–66)

39 (18–65)

50 (30–70)

 - 2–4 weeks

14 (12–16)

14 (11–17)

13 (9–18)

11 (5–21)

22 (8–49)

17 (6–39)

 - 1–3 months

10 (9–13)

9 (7–11)

14 (10–20)

12 (6–23)

17 (5–44)

8 (2–30)

 - >3 months

13 (11–16)

11 (9–14)

14 (10–20)

23 (14–35)

22 (8–49)

25 (11–47)

Previous LBP episodes^b

0.03

 - 0 episodes

16 (14–19)

17 (14–20)

17 (12–22)

6 (2–15)

18 (51–46)

21 (8–43)

 - 1–3 episodes

35 (32–38)

37 (33–41)

33 (27–40)

27 (18–40)

24 (8–52)

29 (14–52)

 - >3 episodes

49 (45–52)

46 (42–50)

50 (44–57)

67 (54–77)

59 (33–81)

50 (30–70)

LBP last year^b

<0.001

 - ≤30 days

74 (72–77)

79 (76–82)

68 (61–74)

58 (46–70)

53 (27–78)

75 (53–89)

 - >30 days

26 (23–28)

21 (18–24)

32 (26–39)

42 (30–54)

47 (22–73)

25 (11–47)

LBP intensity^a

7 (3, 9)

7 (3, 9)

7 (4, 9)

8 (3, 9)

7 (3, 9)

8 (2, 10)

0.07

Leg pain intensity^a

2 (0, 7)

0 (0, 5)

4 (1, 7)

6 (2, 9)

8 (4, 9)

0 (0, 6)

<0.001

Recovery expectations^a

9 (4, 10)

10 (4, 10)

9 (4, 10)

8 (2, 10)

9 (1, 10)

10 (4, 10)

<0.001

Depressive symptoms^a

6 (1, 18)

5 (1, 17)

7.5 (2, 21)

9.5 (2, 21)

6 (2, 34)

7 (2, 19)

<0.001

Fear avoidance beliefs physical activity^a

13 (6, 20)

13 (6, 20)

12 (5, 19)

14 (2, 20)

12 (5, 20)

14 (6, 22)

0.08

Fear avoidance beliefs work^a

11 (3, 26)

10 (3, 26)

13 (2, 24)

12 (2, 31)

17.5 (5,31)

11 (4, 33)

0.10

Start Back Tool^b

<0.001

 - Low risk

54 (51–57)

60 (56–64)

41 (34–48)

44 (32–57)

35 (15–62)

46 (26–67)

 - Medium risk

38 (35–41)

34 (30–38)

47 (40–54)

48 (35–60)

41 (19–67)

42 (23–63)

 - High risk

8 (6–10)

6 (4–8)

13 (8–18)

8 (3–18)

24 (8–52)

13 (4–34)

Activity limitation^a

52 (17, 83)

52 (13, 83)

56 (26, 83)

57 (17, 83)

74 (17, 90)

59 (15, 85)

0.01

General health^a

70 (35, 90)

75 (37, 90)

70 (30, 90)

67 (34, 90)

70 (28, 97)

72 (40, 92)

<.01

All general practice patients (b)

n = 324

‘LBP alone’

n = 97 (48%)

‘LBP + pain above knee’

n = 42 (21%)

‘LBP + pain below knee’

n = 39 (19%)

‘LBP + signs of nerve root involvement’

n = 23 (11%)

Quebec missing

n = 123 (38%)

p-values^§

Age in years^a

46 (27–59)

46 (23–61)

47 (31–60)

49 (34–61)

45 (34–60)

44 (26–58)

0.48

Females^b

55 (49–60)

54 (43–63)

64 (48–78)

46 (31–62)

39 (21–61)

58 (49–67)

0.20

Physical work load^b

0.45

 - Sitting

14 (11–19)

19 (11–29)

6 (1–21)

11 (3–30)

37 (17–62)

18 (11–26)

 - Sitting/walking

32 (27–38)

33 (24–44)

34 (20–52)

36 (20–56)

-

30 (22–39)

 - Light physical work

28 (23–33)

23 (15–34)

23 (11–40)

32 (17–52)

32 (14–57)

31 (22–40)

 - Heavy physical work

25 (21–31)

25 (16–35)

37 (22–55)

21 (9–42)

32 (14–57)

22 (15–31)

Sick leave^b

40 (34–46))

34 (25–45)

54 (37–70))

39 (23–58)

56 (31–78)

37 (29–47)

0.12

Educational level^b

0.47

 - No qualification

20 (16–25)

16 (10–26)

26 (14–42)

26 (13–43)

20 (7–45)

19 (13–28)

 - Vocational training,

18 (14–23)

16 (10–26)

23 (12–40)

17 (8–34)

20 (7–45)

18 (12–26)

 - Higher education < 3 y

22 (18–27)

19 (12–29)

26 (14–42)

17 (8–34)

30 (13–55)

23 (16–31)

 - Higher education 3–4 y

29 (24–34)

31 (22–41)

18 (9–34)

34 (20–52)

25 (10–50)

31 (23–40)

 - Higher education >4 y

6 (4–9)

14 (8–23)

3 (0–17)

3 (0–19)

-

3 (1–8)

Duration of pain^b

0.03

 - 0–2 weeks

39 (33–44)

42 (32–53)

51 (35–67)

20 (9–37)

20 (7–45)

41 (32–50)

 - 2–4 weeks

14 (10–18)

15 (9–25)

5 (1–20)

17 (8–34)

15 (4–40)

14 (8–21)

 - 1–3 months

16 (12–21)

20 (13–30)

8 (2–23)

14 (6–31)

20 (7–45)

15 (10–23)

 - >3 months

32 (27–37)

22 (15–33)

35 (21–52)

49 (32–65)

45 (24–68)

31 (23–40)

Previous LBP episodes^b

0.03

 - 0 episodes

14 (11–19)

23 (15–34)

8 (2–23)

6 (1–21)

5 (1–32)

14 (9–22)

 - 1–3 episodes

24 (19–29)

16 (10–26)

37 (23–54)

23 (11–40)

25 (10–50)

25 (18–34)

 - >3 episodes

62 (56–67)

60 (50–70)

55 (39–71)

71 (54–84)

70 (45–87)

60 (51–69)

LBP last year^b

0.29

 - ≤30 days

51 (45–56)

56 (45–66)

53 (36–68)

37 (22–55)

45 (24–68)

51 (42–60)

 - >30 days

49 (44–55)

44 (34–55)

47 (32–64)

63 (45–78)

55 (32–76)

49 (40–58)

LBP intensity^a

7 (4, 9)

7 (4, 9)

8 (5, 10)

7 (4, 9)

7 (3, 10)

7 (4, 9)

0.35

Leg pain intensity^a

3 (0, 9)

0 (0, 6)

5 (0, 9)

7 (3, 9)

6 (4, 10)

3 (0, 9)

<0.001

Recovery expectations^a

6 (0, 10)

7 (2, 10)

8 (0, 10)

3 (0, 9)

5 (0, 7)

7 (1, 10)

<0.001

Depressive symptoms^a

9 (2, 26)

8 (2, 22)

7 (1, 27)

15 (2.6, 39)

10 (4, 28)

9 (2, 25)

0.09

Fear avoidance beliefs physical activity^a

14 (6, 21)

13 (3, 21)

15 (8, 20)

14.5 (5, 22)

17 (9, 24)

13.5 (6, 21)

0.01

Fear avoidance beliefs work^a

14 (3, 28)

11 (3, 27)

18 (6, 27)

16 (4, 30)

23 (12, 38)

14 (3, 29)

0.001

Start Back Tool^b

<0.001

 - Low risk

41 (36–47)

51 (40–62)

31 (17–50)

25 (13–44)

27 (9–57)

44 (35–54)

 - Medium risk

36 (30–41)

28 (19–39)

59 (41–75)

25 (13–44)

33 (13–63)

38 (29–47)

 - High risk

23 (18–28)

21 (14–32)

9 (3–27)

50 32–68)

40 17–68)

18 (12–26)

Activity limitation^a

61 (22, 87)

54 (17, 83)

61 (35, 87)

74 (14, 96)

72 (31, 91)

65 (22, 87)

<0.001

General health^a

60 (26, 90)

65 (35, 90)

60 (19, 90)

50 (20, 86)

50 (16, 74)

65 (25, 90)

0.005