Skip to main content

Table 6 Factors associated with the presence of exclusionary condition among subjects classified as chronic fatigue syndrome (CFS) at clinic evaluation

From: An evaluation of exclusionary medical/psychiatric conditions in the definition of chronic fatigue syndrome

Characteristics    Exclusionary condition Odds ratio (OR)
  All Yes No Unadjusted ORs Adjusted ORs
  n = 210 n = 100 (48%) n = 110 (52%) (95% CI) (95% CI)
Telephone Classification         
   CFS-like 169 80.48 85 50.30 84 49.70 1.75 (0.87-3.54) 1.48 (0.61-3.56)
   Unwell 41 19.52 15 36.59 26 63.41 1.00 1.00
Age (years), mean (standard deviation, SD) 45.06 (9.65) 45.99 (8.98) 44.22 (10.19) 1.21 (0.92-1.59) 1.06 (0.74-1.54)
Sex         
   Male 38 18.10 18 47.37 20 52.63 0.99 (0.49-2.00) 1.65 (0.69-3.92)
   Female 172 81.90 82 47.67 90 52.33 1.00 1.00
Race         
   Black 35 16.67 14 40.00 21 60.00 0.67 (0.32-1.40) 0.56 (0.20-1.52)
   Other 13 6.19 5 38.46 8 61.54 0.63 (0.20-1.99) 0.62 (0.15-2.51)
   White 162 77.14 81 50.00 81 50.00 1.00 1.00
Residential areas         
   Rural 106 50.48 54 50.94 52 49.06 2.28 (0.99-5.29) 1.47 (0.51-4.20)
   Urban 72 34.29 36 50.00 36 50.00 2.20 (0.91-5.30) 1.53 (0.55-4.27)
   Metropolitan 32 15.24 10 31.25 22 68.75 1.00 1.00
Body mass index (kg/m2), mean (SD) 28.69 (5.18) 29.50 (5.42) 27.95 (4.87) 1.36 (1.03-1.79) 1.47 (1.05-2.06)
Multidimensional fatigue inventory        Per SD increment Per SD increment
   General fatigue 17.05 (2.36) 17.34 (2.09) 16.79 (2.57) 1.27 (0.96-1.70) 1.22 (0.81-1.84)
   Physical fatigue 14.52 (3.31) 14.88 (3.22) 14.19 (3.38) 1.24 (0.94-1.63) 0.83 (0.52-1.34)
   Reduced Activity 11.96 (4.10) 12.33 (4.19) 11.63 (4.02) 1.19 (0.90-1.56) 0.83 (0.54-1.26)
   Reduced Motivation 12.44 (3.38) 13.05 (3.63) 11.89 (3.05) 1.43 (1.07-1.89) 1.44 (0.94-2.20)
   Mental fatigue 14.05 (3.75) 14.49 (3.72) 13.65 (3.75) 1.25 (0.95-1.65) 1.19 (0.80-1.77)
SF-36        Per SD increment Per SD increment
   Physical functioning 57.37 (24.54) 52.83 (24.01) 61.45 (24.40) 0.70 (0.53-0.92) 0.77 (0.28-2.12)
   Role physical 9.05 (19.45) 5.50 (13.09) 12.27 (23.40) 0.67 (0.48-0.93) 0.63 (0.40-1.00)
   Bodily pain 38.30 (19.86) 35.66 (18.93) 40.70 (20.46) 0.77 (0.58-1.02) 0.60 (0.27-1.31)
   Social functioning 49.82 (24.74) 47.25 (26.03) 52.16 (23.39) 0.82 (0.62-1.08) 1.24 (0.62-2.46)
   Mental health 54.27 (22.15) 52.04 (21.59) 56.29 (22.55) 0.82 (0.63-1.08) 1.38 (0.55-3.46)
   Role emotional 27.46 (37.36) 23.66 (35.23) 30.90 (39.03) 0.82 (0.62-1.08) 0.94 (0.55-1.61)
   Vitality 22.29 (16.21) 21.55 (16.96) 22.95 (15.54) 0.92 (0.70-1.20) 1.20 (0.72-1.99)
   General health 40.17 (19.46) 38.10 (20.87) 42.05 (17.97) 0.81 (0.62-1.07) 0.99 (0.51-1.92)
   PCS* 36.67 (9.92) 35.31 (9.91) 37.91 (9.81) 0.77 (0.58-1.01) 1.47 (0.17-12.75)
   MCS* 36.75 (12.58) 35.75 (12.78) 37.67 (12.39) 0.86 (0.65-1.13) 0.69 (0.12-3.99)
   HUI2* 61.94 (10.80) 59.95 (10.96) 63.76 (10.37) 0.69 (0.52-0.92) Not included
SI        Per SD increment Per SD increment
   SI_CFS 49.03 (16.60) 50.20 (15.94) 47.97 (17.17) 1.15 (0.87-1.50) 0.68 (0.42-1.11)
   SI_NCFS 36.98 (18.68) 39.95 (19.63) 34.24 (17.40) 1.37 (1.03-1.82) 1.47 (0.93-2.32)
  1. Note: adjusted ORs were obtained for the multiple logistic regression models including all variables in the table; p-value < 0.05 were in bold font.
  2. * Nichole's health utility index 2 (HUI2) was included in the multivariate model because it is a linear combination of 8 SF-36 subscales and strongly correlated with Physical Component Summary (PCS) and Mental Component Summary (MCS).
  3. CI: confidence interval; SI_CFS: symptom inventory summary score of 8 CFS symptoms; SI_NCFS: symptom inventory summary score of non-CFS symptoms