Table 1.

Basic characteristics of the study participants where P-values refer to the Kruskal-Wallis test and the Pearson’s χ2 test for quantitative and categorical variables, respectively.

	ME/CFS_S0 (n = 42)	ME/CFS_S1 (n = 42)	ME/CFS_S2 (n = 92)	ME/CFS_S3 (n = 46)	MS (n = 46)	P-value
Age						0.007
Mean (SD)	44.5 (10.7)	41.0 (13.0)	43.4 (10.9)	41.1 (10.5)	48.8 (7.10)
Median [Min, Max]	44.0 [23.0, 60.0]	42.5 [18.0, 60.0]	44.0 [18.0, 59.0]	42.0 [19.0, 57.0]	50.5 [31.0, 58.0]
Gender						0.578
Female	33 (78.6%)	32 (76.2%)	74 (80.4%)	32 (69.6%)	38 (82.6%)
Male	9 (21.4%)	10 (23.8%)	18 (19.6%)	14 (30.4%)	8 (17.4%)
ME/CFS Diagnosis						0.143
1994 CDC Only	9 (21.4%)	9 (21.4%)	6 (6.5%)	6 (13.0%)	NA
2003 CCC Only	0 (0%)	1 (2.4%)	1 (1.1%)	1 (2.2%)	NA
1994 CDC/2003 CCC	33 (78.6%)	32 (76.2%)	85 (92.4%)	39 (84.8%)	NA
Disease course						0.317
Constantly getting worse	4 (9.5%)	4 (9.5%)	16 (17.4%)	8 (17.4%)	10 (21.7%)
Constantly improving	0 (0%)	1 (2.4%)	0 (0%)	1 (2.2%)	0 (0%)
No change	1 (2.4%)	1 (2.4%)	7 (7.6%)	2 (4.3%)	2 (4.3%)
Relapsing and remitting	3 (7.1%)	4 (9.5%)	6 (6.5%)	8 (17.4%)	10 (21.7%)
Fluctuating	16 (38.1%)	15 (35.7%)	30 (32.6%)	11 (23.9%)	14 (30.4%)
Missing Data	18 (42.9%)	17 (40.5%)	33 (35.9%)	16 (34.8%)	10 (21.7%)
Disease Severity						0.007
Mild/Moderate	38 (90.5%)	38 (90.5%)	64 (69.6%)	34 (73.9%)	NA
Severe	4 (9.5%)	4 (9.5%)	28 (30.4%)	12 (26.1%)	NA
Disease Onset (Infection)						NA
Don't know	42 (100%)	0 (0%)	0 (0%)	0 (0%)	14 (30.4%)
No, did not have an infection at onset	0 (0%)	42 (100%)	0 (0%)	0 (0%)	22 (47.8%)
Yes, but not confirmed by a lab test	0 (0%)	0 (0%)	92 (100%)	0 (0%)	1 (2.2%)
Yes, confirmed by a lab test	0 (0%)	0 (0%)	0 (0%)	46 (100%)	0 (0%)
Missing Data	0 (0%)	0 (0%)	0 (0%)	0 (0%)	9 (19.6%)
Disease Duration						0.754
Mean (SD)	12.7 (8.39)	11.8 (8.60)	12.1 (8.52)	13.2 (8.22)	NA (NA)
Median [Min, Max]	11.4 [1.40, 37.0]	10.3 [1.60, 38.0]	11.2 [0.200, 39.9]	12.0 [1.10, 29.3]	NA [NA, NA]
Missing	1 (2.4%)	2 (4.8%)	2 (2.2%)	0 (0%)	46 (100%)