Table 2.

Person‐years, mortality rates and risk ratios for DRP mortality, by interruptions to continuity of OST adjusted for covariates.

	DRP		DRP mortality rate	Unadjusted analysis			Adjusted analysis
	Person‐years (py)	Deaths	(per 100 py)	RR	95% CI	P‐value	aRR	95% CI	P‐value
Interruptions to OST continuitya
Weeks 1–4 following transfer between services	248	0	0.00	–	–	–	–	–	–
Weeks 1–4 out of treatment	–	–	1.29	3.29	1.18–9.16	0.022	4.04	1.43–11.43	0.009
Weeks 5–52 out of treatment	–	–	0.27	0.69	0.21–2.22	0.530	1.00	0.30–3.34	0.995
Weeks 1–4 of treatment initiationb	–	–	1.11	2.85	1.02–7.92	0.045	3.40	1.20–9.64	0.021
Weeks 5+ in treatment (same treatment provider)	11 266	44	0.39	1.00	–	–	1.00	–	–
Gender
Women	4336	25	0.58	1.72	1.01–2.93	0.045	1.89	1.09–3.28	0.023
Men	8964	30	0.33	1.00	–		1.00	–	–
Age (in years)				1.04	1.01–1.08	0.023	1.05	1.01–1.09	0.011
Median methadone dose (last treatment)
< 60 mg	4304	13	0.30	0.70	0.37–1.33	0.280	0.63	0.33–1.23	0.176
61–120 mg	8399	36	0.43	1.00	–		1.00	–	–
> 120 mg	597	6	1.01	2.35	0.99–5.57	0.050	2.32	0.97–5.52	0.058
History of incarceration
No	9595	40	0.42	1.00	–
Yes	3705	15	0.40	0.97	0.54–1.76	0.920
Mental and behavioural disordersc
No	4194	11	0.26	1.00	–		1.00	–	–
Yes	9106	44	0.48	1.84	0.95–3.57	0.070	1.62	0.83–3.16	0.158

^aContinuous treatment with the same treatment provider for ≥ 5 weeks was set as the reference group;

^bthe first 4 weeks of treatment initiation refers to initiation following a period out of treatment;

^cdetermined by the RxRisk tool mapped to ICD‐10 disease categories. OST = opioid substitution treatment; aRR = adjusted relative risk; RR = relative risk; DRP = drug‐related poisoning; CI= confidence interval.

Bold type highlights results for the primary exposure variable (interruptions to continuity of OST).