Table 2.

Factors possibly associated with positive urine morphine test in MMT participants

Variable	N	Number of urine test positive (%)	OR (95 % CI)	P
Cumulative years of heroin use
<5	101	40 (39.6 %)	1
5–9	134	56 (41.8 %)	1.10 (0.65–1.85)	0.736
10–14	190	85 (44.7 %)	1.24 (0.76–2.02)	0.400
≥15	168	73 (43.5 %)	1.17 (0.71–1.94)	0.536
Missing	5	2 (40.0 %)	–	–
Dosages of heroin use per time (g)
<0.5	197	94 (47.7 %)	1
0.5–0.9	212	85 (40.1 %)	0.73 (0.50–1.09)	0.121
≥1.0	187	77 (41.2 %)	0.77 (0.51–1.15)	0.198
Missing	2	0 (0.0 %)	–	–
Frequency of heroin use in one-day
<3	285	111 (38.9 %)	1
≥3	312	144 (46.2 %)	1.34 (0.97–1.86)	0.076
Missing	1	1 (100.0 %)	–	–
Route of heroin use
Inhalation	315	123 (39.0 %)	1
Inhalation + Injection	82	47 (57.3 %)	2.10 (1.28–3.43)	0.003
Injection	196	86 (43.9 %)	1.22 (0.85–1.75)	0.280
Missing	5	0 (0.0 %)	–	–
Daily MMT dosages (mg)
<60	336	140 (41.7 %)	1
60–80	191	71 (37.2 %)	0.83 (0.58–1.19)	0.312
>80	70	45 (64.3 %)	2.52 (1.48–4.30)	0.001
Missing	1	0 (0.0 %)	–	–
Cumulative years of methadone treatment
≤1	65	22 (33.8 %)	1
>1–3	156	68 (43.6 %)	1.51 (0.83–2.76)	0.180
>3–6	223	100 (44.8 %)	1.59 (0.89–2.83)	0.116
>6	152	65 (42.8 %)	1.46 (0.80–2.68)	0.221
Missing	2	1 (50.0 %)	–	–