Table 3.
Sub-group analyses on primary outcome (full-analysis set).
| Analysis—baseline sub-group | SoC (n = 156) | BUP-XR (n = 158) | Adjusted IRR (95% CI) | p-value |
|---|---|---|---|---|
| CGI-S—extremely mild–mild vs. moderate–extremely severe | ||||
| Treatment group | 102.84 (6.19) | 121.48 (4.91) | 1.06 (1.01–1.12) | 0.029 |
| CGI-S | 0.68 (0.52–0.88) | 0.004 | ||
| Interaction | 1.32 (1.25–1.39) | 0.001 | ||
| CGI-S (extremely mild–mild) | 119.97 (2.66) | 127.17 (1.73) | ||
| CGI-S (moderate–extremely) | 81.53 (11.82) | 114.23 (11.88) | ||
| Cocaine use—use in past 28 days | ||||
| Treatment group | 104.59 (7.59) | 122.74 (5.07) | 1.05 (0.99–1.12) | 0.092 |
| Cocaine use | 118.10 (3.56) | 124.59 (3.48) | 0.78 (0.55–1.11) | 0.172 |
| Interaction | 1.24 (0.94–1.63) | 0.124 | ||
| Benzodiazepines—use in past 28 days | ||||
| Treatment group | 104.35 (9.93) | 123.42 (4.79) | 1.19 (1.04–1.35) | 0.010 |
| Benzodiazepine use | 104.10 (10.82) | 123.41 (5.22) | 1.01 (0.93–1.10) | 0.827 |
| Interaction | 0.99 (0.91–1.07) | 0.821 | ||
| Time in treatment before study enrolment—less than 28 days vs. 28 days or more | ||||
| Treatment group | 104.09 (8.44) | 122.11 (5.59) | 1.13 (1.08–1.18) | 0.001 |
| Time (longer) | 109.91 (4.56) | 124.07 (3.09) | 0.80 (0.54–1.19) | 0.271 |
| Interaction | 1.18 (0.94–1.46) | 0.144 | ||
| COVID-19 restrictions—recruitment before vs. aftera | ||||
| Treatment group | 104.53 (10.02) | 123.70 (4.67) | 1.19 (1.06–1.34) | 0.004 |
| Recruitment before restrictions | 108.35 (9.21) | 126.62 (3.36) | 1.05 (0.96–1.14) | 0.271 |
| Interaction | 0.98 (0.91–1.07) | 0.684 |
Analysis period is day 0–168; All means adjusted.
All analysis is mixed-effects, negative binomial regression with baseline drug injecting status (fixed effect), treatment clinic (random intercept), and treatment group x sub-group interaction.
BUP-XR, extended-release buprenorphine; CGI-I, Clinical Global Impression–Severity; IRR, incidence rate ratio; SoC, standard-of-care.
a
Recruitment paused in first study clinic on 20 March 2020 (n = 76); recruitment resumed in all study clinics on 12 June 2020 (n = 238).