Table 3.

Multivariate analysis of severe post-exertional malaise in the group of elevated lactate.

	p-value	OR [95% CI]
Sex (male)	0.42	1.46 [0.58–3.66]
Age at onset disease ≥34 years	0.93	1.04 [0.46–2.31]
PEM score ≥12	0.03	2.47 [1.10–5.55]
Reactive depression	0.81	0.86 [0.37–2.17]
Fibromyalgia	0.52	0.570[0.23–2.12]
Irritable bowel syndrome	0.31	0.66 [0.29–1.48]
Serum zinc deficit	0.44	1.41 [0.59–3.35]
Serum 25-hydroxyvitamin D deficit	0.38	1.45 [0.63–3.33]
Low plasma cortisol levels	0.77	1.16 [0.43–3.17]

Notes: OR [95% CI]: Odds Ratio with 95% Confidence interval; PEM: post-exertional malaise; Multivariate analysis was performed with logistic regression. The variable to explain was the lactate group (elevated or normal). The variables included in the model were those present in the table as well treated sleep apnoea syndrome (p = 0.10) and treated Hashimoto’s thyroiditis (p = 0.41).