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Table 5 MFI, SF-36 and Symptom Inventory Criteria for CFS - Comparison of CFS Cases identified with Two Methods of Applying the 1994 Case Definition

From: Methods of applying the 1994 case definition of chronic fatigue syndrome – impact on classification and observed illness characteristics

  CFS Classification (non-overlapping categories)
Criteria Both Methods Method 1 Only Method 2 Only
  (n=44; M1/M2) (n=15; only M1) (n=27; only M2)
(1) MFI Criterion (one of two cutoffs)    
 (i) General Fatigue ≥ 13* 42 (95.45 %) 9 (60.00 %) 26 (96.30 %)
 (ii) Reduced Activity ≥ 10 34 (77.27 %) 7 (46.67 %) 18 (66.67 %)
 Met at least one* 44 (100 %) 11 (73.33 %) 27 (100 %)
(2) SF-36 Criterion (one of four cutoffs)    
 (iii) Physical Functioning ≤ 70* 32 (72.73 %) 3 (20.00 %) 14 (51.85 %)
 (iv) Role Physical ≤ 50* 33 (75.00 %) 4 (26.67 %) 19 (70.37 %)
 (v) Social Functioning ≤ 75* 42 (95.45 %) 11 (73.33 %) 25 (92.59 %)
 (vi) Role Emotional ≤ 66.67 29 (65.91 %) 6 (40.00 %) 11 (40.74 %)
 Met at least one* 44 (100 %) 11 (73.33 %) 27 (100 %)
(3) CDC Symptom Criterion (Both cutoffs)    
 (vii) ≥ 4 CFS Symptoms lasting ≥ 6 months 44 (100 %) 15 (100 %) 27 (100 %)
 (viii) Summary Score ≥ 25* 44 (100 %) 5 (33.33 %) 27 (100 %)
 Met both 44 (100 %) 5 (33.33 %) 27 (100 %)
Meet all criteria (1),(2), (3) 44 (100 %) 0 27 (100 %)
Meets SF-36 Criterion based on Role Emotional Alone 0 0 0
  Total number of criteria (i)-(viii) met (8 maximum)    
   1   1 (6.67 %)  
   2   1 (6.67 %)  
   3   3 (20.00 %)  
   4 2 (4.55 %) 5 (33.33 %) 1 (3.70 %)
   5 7 (15.91 %) 3 (20.00 %) 7 (25.93 %)
   6 4 (9.09 %) 1 (6.67 %) 8 (29.63 %)
   7 15 (34.09 %) 1 (6.67 %) 8 (29.63 %)
   8 16 (36.36 %) 0 3 (11.11 %)
  1. * indicates p-values < 0.05 for χ2 testing of the independence across three groups