Table 1. Characteristics of the study population.

Phase	variable	case	control	P
Training set	Mean age, years ± SD	61.07 ± 9.15	60.23 ± 9.09	0.725*
(case = 30, control = 30)	Sex
	Male	28 (82.9%)	26 (84.0%)	0.671†
	Female	2 (17.1%)	4 (16.0%)
Validation set	Mean age, years ± SD	63.20 ± 6.19	62.33 ± 6.48	0.598*
(case = 30, control = 30)	Sex
	Male	28 (93.3%)	27 (90/0%)	1.000†
	Female	2 (6.7%)	3 (10.0%)
Testing set
(case = 90, control = 90)	Mean age, years ± SD	61.78 ± 9.21	62.37 ± 8.77	0.651*
	Sex
	Male	72 (80.0%)	70 (77.8%)	0.855†
	Female	18 (20.0%)	20 (22.2%)

^*P for student t tests

^†P for χ² tests.