Table 4.

Association of pyridostigmine bromide use with chronic illness in BChE subgroups: evaluation using two case definitions

	Use of PB by all Gulf War veterans (n = 304)			Use of PB by butyrylcholinesterase genetic subgroups
				Common BChE variants (U/U and U/K) (n = 276)			Less common BChE variants (K/K, U/AK, U/A, A/F, AK/F) (n = 28)
Case definition	% cases exposed	% controls exposed	OR (95% C.I.)	% cases exposed	% controls exposed	OR (95% C.I.)	% cases exposed	% controls exposed	OR (95% C.I.)
GWI (Kansas case definition)*	72%	44%	3.21 (1.97–5.24)	69%	46%	2.68 (1.62–4.44)	92%	23%	40.00 (3.58–447)
CMI (CDC case definition)↑	63%	46%	1.99 (1.23–3.22)	62%	49%	1.73 (1.05–2.84)	78%	22%	11.37 (1.65–78.4)

BChE = butyrylcholinesterase, PB = pyridostigmine bromide, CDC = U.S. Centers for Disease Control and Prevention, OR = prevalence odds ratio, C.I. = confidence interval.

^*Gulf War illness, as defined in Steele [1].

^↑Chronic multisymptom illness, as defined in Fukuda et al. [32].