Skip to main content
. 2023 Feb 27;34:100718. doi: 10.1016/j.lanwpc.2023.100718

Table 3.

Cox regression of factors associated with HIV incidence among the people who inject drugs (PWID) attending the drop-in centres in Kachin, 2008–2020.

Group Model 1; all sites, 2008–2020
 Model 2; HPN and MGG, 2008–2020
 Model 3; all sites, 2012–2020
 Model 4; HPN and MGG, 2012–2020
aHR (adjusted) 95% CI p-value aHR (adjusted) 95% CI p-value aHR (adjusted) 95% CI p-value aHR (adjusted) 95% CI p-value
Male PWID 1 1 1 1
Female PWID 1.09 0.54–2.20 0.814 0.78 0.25–2.46 0.670 1.04 0.49–2.21 0.916 0.58 0.18–1.85 0.358
Age <25 yrsa n/a n/a n/a n/a
Age ≥25 yrsa n/a n/a n/a n/a
Hopin 1 1 1 1
Mogaung 0.76 0.56–0.92 0.009 0.82 0.65–1.04 0.103 0.75 0.59–0.96 0.023 0.98 0.77–1.23 0.842
Myitkyina 1.26 0.97–1.65 0.085 n/a 1.21 0.92–1.59 0.178 n/a
Year of HIV test 0.85 0.81–0.88 <0.001 0.91 0.87–0.95 <0.001 0.88 0.84–0.93 <0.001 0.893 0.88–0.99 0.023
Length of follow-up <3 yrsa n/a n/a 1 1
Length of follow-up ≥3 yrsa n/a n/a 0.58 0.43–0.78 <0.001 0.58 0.41–0.81 0.001
Injected within 6 wks 1.74 1.35–2.25 <0.001 n/a 1.90 1.47–2.46 <0.001 n/a
Not injected within 6 wks 1 n/a 1 n/a
No response recordedb 1.12 0.59–2.13 0.730 n/a 0.75 0.53–1.06 0.107 n/a
Shared needles within 6 wks 2.00 1.48–2.70 <0.001 2.37 1.74–3.23 <0.001 n/a n/a
Not shared within 6 wks 1 1 n/a n/a
No response recordedb 0.58 0.31–1.09 0.089 0.43 0.33–0.58 <0.001 n/a n/a
NSP mediumc n/a n/a 1 1
NSP lowc n/a n/a 1.08 0.80–1.45 0.618 0.89 0.63–1.27 0.536
NSP highc n/a n/a 0.78 0.60–1.01 0.061 0.64 0.48–0.84 <0.001
Reports no polydrug used 1 n/a 1 n/a
Reports polydrug used 0.98 0.63–1.51 0.924 n/a 1.08 0.70–1.67 0.716 n/a
No response recorded 0.82 0.59–1.13 0.227 n/a 0.68 0.48–0.97 0.033 n/a
IDU duration <2 yrs 1 1 1 1
IDU duration 2–<5 yrs 0.54 0.34–0.86 0.010 0.55 0.31–0.97 0.039 0.45 0.28–0.73 0.001 0.47 0.26–0.83 0.009
IDU duration 5–<10 yrs 0.22 0.13–0.35 <0.001 0.20 0.11–0.35 <0.001 0.20 0.12–0.32 <0.001 0.18 0.10–0.32 <0.001
IDU duration ≥10 yrs 0.14 0.08–0.23 <0.001 0.13 0.07–0.24 <0.001 0.13 0.07–0.21 <0.001 0.11 0.06–0.21 <0.001
No response recorded 0.18 0.11–0.30 <0.001 0.18 0.09–0.33 <0.001 0.16 0.09–0.27 <0.001 0.14 0.08–0.27 <0.001
Never on OAT during follow-upe n/a 1 n/a 1
Prior to starting OATe n/a 0.88 0.67–1.15 0.345 n/a 0.87 0.66–1.15 0.324
After OAT stoppede n/a 0.96 0.59–1.57 0.880 n/a 1.08 0.66–1.77 0.769
Currently on OATe n/a 0.50 0.37–0.68 <0.001 n/a 0.36 0.27–0.48 <0.001

Multiple adjusted models (numbered 1–4) were required as information linking PWID to opioid agonist therapy (OAT) was only available at Hopin (HPN) and Mogaung (MGG), and NSP coverage was available from 2012 to 2020. Model 1 included PWID at all sites but excluding OAT, model 2 analysed the same variables with the addition of OAT, but was restricted to PWID from Hopin (HPN) and Mogaung (MGG). Models 3 (all sites) and 4 (HPN and MGG, including OAT) were similar, but also included NSP coverage with length of follow-up being restricted to 2012–2020. Adjusted Hazard ratios (aHR) are given, with 95% confidence intervals (95% CI) and p-values (p). The reference group is indicated with a value 1, and n/a (not applicable) is used to indicate that analyses in these variables were not included in the model.

a

Age was excluded from the regression analysis as it was co-linear with IDU duration. Length of follow up was only included in models 3 and 4 as there were no PWID with <3 yrs of follow up prior to 2012.

b

25.1% of PWID were not asked if they had injected within the last 6 weeks, and 45.6% were not asked if they had shared needles in the last 6 weeks.

c

Needle and syringe provision (NSP) coverage was defined by calculating the median coverage over 6-month periods between 2012 and 2020. A low coverage period was assigned if the number of syringes distributed was below the lower quartile of the 6-monthly number of syringes distributed over 2012–2020, while a high coverage period was assigned if the number of syringes distributed was above the upper quartile; otherwise, the period was assigned as being medium coverage (see Supplementary Table S1).

d

Polydrug use was recorded as ‘yes’ for PWID taking multiple different classes of drugs. This was typically heroin or other opiates plus either amphetamines, yama (a mixture of methamphetamine and caffeine widely used in South East Asia) or alcohol. The majority of PWID in the study reported taking either heroin and/or opiates, which were considered the same drug class and recorded as ‘no polydrug use’. Polydrug use was excluded from the OAT adjusted models 2 and 4 as polydrug use is very rare in HPN (reported by n = 1).

e

For the analysis of OAT, ‘Prior to starting OAT’ includes all test records of PWID that take OAT during follow-up but have not started yet. ‘After OAT stopped’ includes all test records of PWID that take OAT during follow-up but have now stopped taking OAT. ‘Never on OAT’ during follow-up includes test records of PWID who never took OAT. ‘Currently on OAT’ includes the test records of PWID after their start date of taking OAT and excludes test records of PWID after they discontinued OAT.