Table 2 Environmental exposures documented in selected juvenile idiopathic inflammatory myopathy phenotypes

Exposures within 1 Year of Diagnosis

Infections

 Any Infection

49 (56.3)

5 (35.7)

4 (80.0)

0.294

19 (57.6)

18 (60.0)

6 (35.3)

9 (64.3)

0.135

 Gastroenteritis

9 (10.3)

1 (7.1)

1 (20.0)

0.468

4 (12.1)

3 (10.0)

0 (0.0)^d

4 (28.6)^d

0.032^d

NC^d

 Strep Throat

20 (23.2)

2 (14.3)

1 (20.0)

0.729

4 (12.1)

9 (31.0)

3 (17.6)

5 (35.7)

0.102

 URI

13 (14.9)

1 (7.1)

0 (0.0)

0.685

5 (15.2)

5 (16.7)

2 (11.8)

1 (7.1)

0.647

 Influenza

7 (8.0)

0 (0.0)

0 (0.0)

0.589

4 (12.1)

1 (3.3)

1 (5.9)

1 (7.1)

0.357

UV Exposure

 Any Sunburn

43 (50.0)

8 (57.1)

3 (60.0)

0.775

16 (48.5)

14 (46.7)

6 (37.5)

8 (57.1)

0.549

 Median Number of Sunburns

0.5 [0.0–2.0]

1.0 [0.0–1.5]

1.0 [0.0–1.0]

0.823

0.0 [0.0–20.0]

0.0 [0.0–2.0]

0.0 [0.0–1.0]

1.0 [0.0–1.3]

0.786

Heavy Exercises

 Any Heavy Exercise

29 (33.3)

6 (42.9)

2 (40.0)

0.550

9 (27.3)

8 (26.7)

8 (47.0)

8 (57.1)

0.091

 Exercise Resulting in Muscle Pain

18 (20.7)

4 (28.6)

1 (20.0)

0.498

3 (9.0)^e

6 (20.0)

5 (29.4)

6 (42.9)^e

0.013^e

7.5^e (1.6–30.5)

 Prolonged Running

15 (17.2)

2 (14.3)

0 (0.0)

0.579

3 (9.0)^f

4 (13.3)

6 (35.3)^f

2 (14.3)

0.047^f

5.5^f (1.3–21.8)

 Heavy Sports Activity

24 (27.6)

6 (42.9)

1 (20.0)

0.344

8 (24.2)

6 (20.0)

8 (47.0)

7 (50.0)

0.074

Medications

 Any Medication

59 (67.8)

10 (71.4)

5 (100)

0.316

21 (63.6)

21 (70.0)

10 (58.8)^d

13 (92.9)^d

0.045^d

9.1^d (1.1–109.0)

 Antibiotics

42 (48.5)

5 (37.5)

3 (60.0)

0.561

15 (46.9)

16 (53.3)

5 (29.4)

8 (57.1)

0.138

 NSAIDs

24 (28.2)

7 (50.0)

1 (25.0)

0.125

9 (29.0)

10 (33.3)

4 (23.5)

5 (35.7)

0.529

 Seizure Medication

0 (0.0)

0 (0.0)

1 (20.0)

0.054

0 (0.0)

0 (0.0)

0 (0.0)

1 (7.1)

0.298

Immunizations

 Any Immunization

50 (57.5)^a

10 (71.4)^b

0 (0.0)^a,b

0.017^a

NC^a

21 (63.6)

17 (56.7)

9 (52.9)

8 (57.1)

0.549

0.011^b

NC^b

 Influenza

37 (42.5)

7 (50.0)

0 (0.0)

0.080

15 (45.5)

14 (46.7)

5 (29.4)

6 (42.9)

0.356

 Hepatitis B

0 (0.0)^c

2 (15.4)^c

0 (0.0)

0.016^c

NC^c

2 (6.3)

0 (0.0)

0 (0.0)

0 (0.0)

0.492

Weight at Diagnosis

 Overweight/Obese

23 (26.7)

1 (7.1)

1 (20.0)

0.117

10 (31.3)

7 (23.3)

2 (11.8)

3 (21.4)

0.174

 Underweight

6 (7.0)^c

6 (42.9)^c

0 (0.0)

0.002^c

10.0^c (2.8–34.0)

3 (9.4)

4 (13.3)

1 (5.9)

3 (21.4)

0.304

Major Psychosocial Stressors

 Death or Illness of Significant Person

6 (6.9)

1 (7.1)

0 (0.0)

0.999

0 (0.0)

3 (10.0)

2 (11.8)

2 (14.3)

0.084

Exposures Beyond 1 Year of Diagnosis

Major Psychosocial Stressors (within 5 Years of Diagnosis)

 Death or Illness of Significant Person

17 (19.5)

4 (28.6)

1 (20.0)

0.482

4 (12.1)^e

9 (30.0)

2 (11.8)

6 (42.9)^e

0.045^e

5.4^e (1.3–19.6)

Smoke Exposure

 Maternal Smoking during Pregnancy

3 (5.2)

0 (0.0)

0 (0.0)

0.999

1 (4.3)

0 (0.0)

2 (18.2)

0 (0.0)

0.118

 Parental Smoking during Pregnancy

7 (13.2)

0 (0.0)

1 (50.0)

0.222

2 (10.0)

1 (5.3)

2 (18.2)

1 (16.7)

0.430

 Secondhand Smoke Exposure

7 (8.0)

3 (21.4)

2 (40.0)

0.073

3 (9.1)

2 (6.7)

2 (11.8)

2 (14.3)

0.581

Pregnancy Complications

 C Section Birth

23 (36.5)

2 (28.6)

0 (0.0)

0.546

9 (37.5)

8 (40.0)

4 (33.3)

3 (33.3)

0.999

 Birth < 37 weeks

12 (19.3)

3 (42.9)

0 (0.0)

0.169

3 (12.5)

6 (31.6)

4 (33.3)

2 (22.2)

0.153

 Preeclampsia or Gestational Hypertension

4 (6.3)

0 (0.0)

0 (0.0)

0.999

0 (0.0)

3 (15.0)

1 (8.3)

1 (11.1)

0.086

Breastfed

 Breastfed for any period

48 (78.7)

7 (100.0)

3 (100.0)

0.331

17 (70.8)

19 (95.0)^g

7 (58.3)^g

8 (88.9)

0.020^g

13.6^g (1.7–166.1)

 Breastfed for more than 6 months

25 (52.1)

5 (71.4)

1 (33.3)

0.443

7 (41.2)^e

11 (57.9)

2 (28.6)^d

8 (88.9)^d,e

0.035^d

20.0^d (1.5–256.5)

0.036^e

11.4^e (1.2–137.2)

Soy Formula

13 (21.0)

0 (0.0)

1 (33.3)

0.333

6 (26.1)

3 (15.0)

3 (27.3)

0 (0.0)

0.150