Table IV.

Comparison between persistent and non-persistent antibodies: ordinal and scalar variables

	Persistent	Non-persistent	p
Age (y)	63±17	64±18	NS
Follow-up (d)	236 (25–1363)	409 (104–1166)	0.012
N. of tests after first detection	1 (1–2)	2 (1–4)	<0.001
Initial score	3 (2–3)	2 (1–3)	<0.001
Maximum score	3 (2–4)	2 (2–3)	<0.001

Initial and maximum scores are ordinal variables. Age of the patient at the time of detection, length of follow-up, number of tests after first detection are scalar variables. Data are reported as means±1SD, or as medians with the interquartile range in parentheses, as appropriate. The statistical significance of the differences was evaluated using the Mann-Whitney U-test.