Table 3 Clinical/laboratory parameters and FDG uptake score—Univariate Analysis (using unpaired t test and ANOVA)

Age

Less than 30 years

10.44 ± 4.17

0.977

17.68 ± 8.31

0.828

30 to 50 years

10.19 ± 2.69

16.3 ± 4.41

More than 50 years

10.49 ± 4.43

15.85 ± 6.31

Duration of illness

Less than 6 months

11.16 ± 3.83

0.33

17.97 ± 6.62

0.33

Between 6 to 12 months

9.63 ± 2.13

15.25 ± 3.88

More than 12 months

8.98 ± 3.27

14.29 ± 4.88

Sex

Male vs. Female

10.33 ± 3.02 vs. 10.31 ± 3.65

0.99

17.60 ± 6.07 vs. 15.88 ± 5.62

0.44

Clinical diagnosis

Dermatomyositis

11.66 ± 3.34

0.041

19.34 ± 5.2

0.003

Polymyositis

8.89 ± 0

13.5 ± 0

Necrotizing myositis

9.31 ± 0.42

14.19 ± 1.79

Overlap myositis

7.64 ± 2.94

10.99 ± 4.11

Severity of limb weakness

Mild/moderate weakness

9.11 ± 3.06

0.004

14.69 ± 5.27

0.012

Severe weakness

12.74 ± 2.71

20.14 ± 5.09

Serum autoantibodies

Mi2B positivity vs. negative

12.47 ± 3.17 vs. 8.67 ± 2.56

0.001

20.56 ± 5.19 vs. 13.41 ± 4.02

0.000

MSA positive vs. negative

11.21 ± 2.96 vs. 8.24 ± 3.49

0.025

18.16 ± 5.24 vs. 12.68 ± 5.25

0.014

MAA positive vs. negative

7.48 ± 2.81 vs. 11.35 ± 2.99

0.004

11.47 ± 4.08 vs. 18.34 ± 5.19

0.002

ANA positive vs. negative

8.94 ± 3.29 vs. 10.82 ± 3.35

0.183

14.93 ± 6.67 vs. 17.09 ± 5.43

0.372

ESR

Less than 30 mm/hr

10.89 ± 2.84

0.536

17.33 ± 4.78

0.595

More than 30 mm/hr

9.97 ± 4.04

16.01 ± 6.76

Creatine Kinase

Less than 5 X ULN vs. More than 5 X ULN

6.46 ± 3.77 vs. 10.91 ± 2.97

0.012

9.27 ± 3.92 vs. 17.63 ± 5.18

0.005

SGOT

Normal

7.40 ± 4.05

0.077

10.91 ± 4.59

0.03

Above normal but less than 5 X ULN

10.36 ± 3.07

16.55 ± 5.03

More than 5 X ULN

12.48 ± 3.00

20.85 ± 6.50

SGPT

Normal

7.20 ± 3.16

0.007

10.74 ± 3.63

0.002

Above normal but less than 5 X ULN

10.53 ± 2.95

16.84 ± 5.28

More than 5 X ULN

13.25 ± 2.41

22.18 ± 2.64