Table 3.

Interaction analysis according to sex and age among groups

Sub-group	Variable		Survival duration (yr)					Multiple cox regression (ref. maintenance)				Interaction analysisa
			Median	CI	Mean	SE		HR	CI	pvalue		HR	CI	pvalue
ATX and MPH	Sex	Male	1.47	1.23−1.74	2.99	0.15		1.00	-	-		1.00	-	-
		Female	1.41	0.85−1.85	2.46	0.22		1.18	0.98−1.41	0.0772
COM		Male	5.36	1.76−8.75	5.51	0.70		1.00	-	-		0.34	0.12−0.99	0.0481
		Female	10.67	0.43−ND	7.92	1.56		0.19	0.05−0.70	0.0131
SEP		Male	3.78	3.00−6.70	4.95	0.42		1.00	-	-		1.16	0.65−2.04	0.6190
		Female	2.94	0.73−5.30	3.77	0.70		1.53	0.88−2.66	0.1302
ATX and MPH	Age (yr)	< 18	1.62	1.38−1.87	2.98	0.15		1.00	-	-		1.00	-	-
		≥ 18	1.10	0.72−1.36	2.50	0.25		1.21	1.01−1.46	0.0410
COM		< 18	7.53	2.87−10.41	6.40	0.68		1.00	-	-		1.60	0.60−4.30	0.3505
		≥ 18	0.91	0.10−ND	1.14	0.35		6.85	1.94−24.25	0.0029
SEP		< 18	3.67	2.68−5.30	4.79	0.43		1.00	-	-		0.87	0.50−1.51	0.6222
		≥ 18	3.78	2.15−7.05	4.18	0.57		1.17	0.69−1.99	0.5653

ATX, group treated with atomoxetine only; MPH, group treated with methylphenidate only; SEP, group exposed to ATX and MPH but separately used; COM, group exposed to ATX and MPH with combined use; CI, confidence interval; HR, hazard ratio; SE, standard error; ND, not detected.

^aWilcoxon rank sum test, adjusted by age, sex.