Epidemiological and clinical factors associated with post-exertional malaise severity in patients with myalgic encephalomyelitis/chronic fatigue syndrome

Table 2 Epidemiological and clinical patients’ characteristics associated with post-exertional malaise severity in an adjusted model

	p-value	OR [95% CI]^a
Post-exertional malaise severity quartiles
Quartile 1	Reference
Quartile 2	0.25
Quartile 3	0.03
Quartile 4	0.002
Variables
Age at onset^b	0.03	1.8 [1.1–3.0]
Sex (female)	0.30	0.7 [0.4–1.3]
Neurosensory, perceptual and motor disturbances	0.20	6.5 [0.4–108.6]
Sleep disturbances	0.25	4.7 [0.3–65.5]
Susceptibility to viral infections	0.009	2.1 [1.2 –3.7]
Respiratory manifestations	0.06	1.7 [1.0–2.9]
Loss of thermostatic instability	0.24	1.6 [0.7–3.7]

Multivariate analysis was performed with ordinal regression. All variables including age at disease onset, sex, and symptom clusters of ME ICC criteria [3] were included in the initial model. The initial model did not meet the validation conditions: the model significantly differed from the intercept (p = 0.04) but failed to validate the proportional odds assumption (p = 0.015). The final model was created by removing the variables one by one with a descending stepwise method until validation of both the parallel lines test (p = 0.242) and the test on -2log-likelihood ratio from the intercept (p = 0.009)
^aOdds Ratio with 95% Confidence interval
^bAge as a categorical variable with a cut-off ≥ the median age of the study population (32 years)

ISSN: 1479-5876