Introduction
Methods
Study Population
Measures
Statistical Analyses
Ethics
Results
Latent Class Model and Polydrug Use Class Membership
Latent class model | Class 1 Polydrug poly-route injection (%, n) | Class 2 Opiate-stimulant poly-injection (%, n) | Class 3 Non-injection stimulant co-use (%, n) | Class 4 Opiate-opioid poly-injection (%, n) | Class 5 Single drug injection (%, n) | All classes (%, n) | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Class probabilities | 9% | 124 | 7% | 97 | 12% | 174 | 16% | 217 | 56% | 790 | 100% | 1402 |
Primary drug injecteda
| ||||||||||||
Primarily injected opiatesb
| 56% | 69 | 94% | 91 | 58% | 102 | 93% | 201 | 87% | 689 | 82% | 1152 |
Primarily injected ATS | 27% | 33 | 4% | 4 | 42% | 73 | 6% | 13 | 13% | 102 | 16% | 223 |
No primary drug | 17% | 22 | 2% | 2 | 0% | 0 | 1% | 3 | 0% | 0 | 2% | 27 |
Other drugs and route of administration | ||||||||||||
Injected other opiate/opioid | 100% | 41 | 54% | 52 | 0% | 0 | 100% | 217 | 0% | 0 | 23% | 310 |
Injected other stimulant(s)c
| 100% | 107 | 100% | 97 | 0% | 0 | 0% | 0 | 0% | 0 | 15% | 204 |
Other opiate/opioid (non-injection)d
| 100% | 52 | 0% | 0 | 34% | 59 | 0% | 0 | 0% | 0 | 8% | 111 |
Other stimulant (non-injection) | 100% | 104 | 0% | 0 | 87% | 151 | 0% | 0 | 0% | 0 | 19% | 255 |
Number other drug(s) injected | ||||||||||||
One | 64% | 79 | 46% | 45 | 0% | 0 | 97% | 211 | 0% | 0 | 24% | 335 |
Two | 30% | 37 | 45% | 44 | 0% | 0 | 3% | 6 | 0% | 0 | 6% | 87 |
Three | 6% | 8 | 8% | 8 | 0% | 0 | 0% | 0 | 0% | 0 | 1% | 16 |
Citya
| ||||||||||||
St Petersburg | 34% | 42 | 76% | 74 | 8% | 14 | 94% | 205 | 60% | 476 | 58% | 811 |
Kohtla-Järve | 66% | 82 | 24% | 23 | 92% | 160 | 6% | 12 | 40% | 314 | 42% | 591 |
Correlates of Polydrug Class Membership
All PWID (n = 1402)a
| Class 1 Polydrug poly-route injection (n = 124) | Class 2 Opiate-stimulant poly-injection (n = 97) | Class 3 Non-injection stimulant co-use (n = 174) | Class 4 Opiate-opioid poly-injection (n = 217) | Class 5 Single drug injection (n = 790) | Pearson’s X2
| X2 p-valueb
| |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Demographic characteristics | ||||||||||||||
Female gender | 24% | 335 | 28% | 35 | 23% | 22 | 31% | 54 | 21% | 45 | 23% | 179 | 8.26 | 0.082 |
Age <30 years | 38% | 535 |
45%
c
|
56
| 41% | 40 |
52%
c
|
90
| 36% | 77 | 34% | 272 | 21.8 | 0.000 |
Completed secondary school | 26% | 359 | 27% | 34 | 26% | 25 |
25%
c
|
43
| 22% | 47 | 27% | 210 | 19.4 | 0.013 |
Completed higher education | 7% | 96 | 3% | 4 | 6% | 6 | 1% | 2 | 11% | 23 | 8% | 61 | ||
Non-Russian | 10% | 145 |
19%
c
|
23
| 5% | 5 |
17%
c
|
30
| 7% | 14 | 9% | 73 | 25.3 | 0.000 |
Non-regular income | 47% | 657 | 48% | 59 | 46% | 45 |
29%
c
|
49
| 48% | 105 | 51% | 399 | 28.5 | 0.000 |
City (Kohtla-Järve) | 42% | 591 | 66% | 82 | 24% | 23 | 92% | 160 | 6% | 12 | 40% | 314 | 340.9 | 0.000 |
Service characteristicsd
| ||||||||||||||
Drug/substitution treatment | 12% | 161 | 5% | 6 | 10% | 10 | 15% | 26 | 12% | 25 | 12% | 94 | 7.7 | 0.103 |
Contact with NSP | 43% | 570 | 54% | 62 |
28%
c
|
26
|
77%
c
|
125
|
19%
c
|
40
| 44% | 317 | 143.9 | 0.000 |
Injecting risk behaviours (last month) | ||||||||||||||
Injecting < 5 years | 7% | 96 |
11%
c
|
13
| 4% | 4 |
14%
c
|
24
| 2% | 5 | 6% | 50 | 24.2 | 0.000 |
Injecting daily or more | 31% | 427 | 42% | 52 |
53%
c
|
51
|
20%
c
|
34
|
37%
c
|
81
| 27% | 209 | 50.7 | 0.000 |
Injected ≥ twice a day | 46% | 642 |
61%
c
|
76
|
70%
c
|
68
| 43% | 74 |
50%
c
|
107
| 40% | 317 | 47.1 | 0.000 |
Shared needles/syringes | 36% | 502 | 31% | 38 |
55%
c
|
53
|
11%
c
|
19
|
57%
c
|
122
| 34% | 270 | 105.3 | 0.000 |
Lent needles/syringes | 37% | 520 | 32% | 39 |
57%
c
|
55
|
15%
c
|
25
|
53%
c
|
114
| 37% | 287 | 78.3 | 0.000 |
Shared drug paraphernalia | 42% | 594 | 35% | 43 |
58%
c
|
56
|
16%
c
|
27
|
64%
c
|
139
| 42% | 329 | 105.7 | 0.000 |
Filled from working syringe | 33% | 462 | 33% | 41 |
47%
c
|
46
|
13%
c
|
23
| 40% | 86 | 34% | 266 | 44.4 | 0.000 |
Sexual risk behaviours (last 6 months) | ||||||||||||||
Any sex in last 6 months | 78% | 1092 | 81% | 100 |
87%
c
|
84
|
85%
c
|
146
| 74% | 160 | 76% | 602 | 13.0 | 0.011 |
≥2 sex partners | 43% | 447 | 42% | 36 |
54%
c
|
45
|
32%
c
|
43
|
54%
c
|
87
| 41% | 236 | 20.8 | 0.000 |
Regular sex partner injects | 56% | 438 | 60% | 42 | 67% | 33 |
57%
c
|
70
|
73%
c
|
63
| 51% | 230 | 18.3 | 0.001 |
Casual sex partner injects | 58% | 218 | 63% | 27 | 66% | 27 | 52% | 24 |
78%
c
|
46
| 50% | 94 | 16.3 | 0.003 |
Ever paid for sex | 5% | 54 | 9% | 8 | 4% | 3 | 6% | 8 | 2% | 3 | 6% | 32 | 4.7 | 0.319 |
Serological markerse
| ||||||||||||||
HIV test positive | 58% | 818 | 53% | 66 | 61% | 59 | 60% | 105 | 59% | 127 | 58% | 461 | 1.87 | 0.759 |
HCV reactive | 74% | 441 | 72% | 59 | 65% | 15 | 73% | 116 | 75% | 9 | 77% | 242 | 2.75 | 0.599 |
HSV positive | 32% | 185 | 31% | 24 | 39% | 9 | 27% | 43 | 50% | 6 | 34% | 103 | 4.28 | 0.368 |
Adjusted odds ratios (95% CI) | ||||
---|---|---|---|---|
Reference group: Class 5 single drug injection | Class 1 Polydrug polyroute injection | Class 2 Opiate-stimulant poly-injection | Class 3 Non-injection stimulant co-use | Class 4 Opiate-opioid poly-injection |
Demographic and services | ||||
Female gender | 1.1 (0.7–2.0) | 0.8 (0.4–1.7) | 1.4 (0.9–2.1) | 0.8 (0.5–1.2) |
Age <30 | 1.3 (0.9–1.8) | 1.7 (1.0–2.9) | 1.5 (1.0–2.2) | 1.6 (1.1–2.3)a
|
Non-Russian | 1.8 (1.1–3.1)a
| 0.8 (0.3–2.1) | 1.1 (0.6–1.9) | 1.6 (1.1–2.4)a
|
Completed secondary school | 0.8 (0.5–1.3) | 0.9 (0.5–1.6) | 0.7 (0.5–1.0)c
| 0.9 (0.5–1.5) |
Non-regular income | 1.0 (0.7–1.6) | 0.7 (0.4–1.2) | 0.6 (0.5–0.7)c
| 0.8 (0.5–1.1) |
City (Kohtla-Järve) | 3.4 (1.7–6.6)a
| 0.5 (0.3–1.0) | 14.9 (7.8–28.9)c
| 0.1 (0.1–0.2)a
|
Service characteristicsb
| ||||
Contact with NSP (last 6 weeks) | 0.7 (0.4–1.3) | 0.7 (0.4–1.3) | 1.0 (0.6–1.6) | 0.9 (0.6–1.3) |
Drug treatment (last 12 months) | 0.3 (0.1–1.5) | 0.4 (0.2–1.6) | 0.7 (0.3–1.5) | 0.7 (0.2–2.3) |
Injecting risk behaviours (last month) | ||||
Injecting <5 years | 1.1 (0.7–1.9) | 1.6 (0.4–6.3) | 0.7 (0.4–1.3) | 1.8 (0.5–5.9) |
Injected daily or more | 2.5 (1.1–5.7)a
| 3.0 (1.5–5.8)a
| 0.9 (0.5–1.5) | 1.3 (1.0–1.8) |
Injected ≥ twice a day | 2.7 (1.3–5.9)a
| 4.0 (2.3–6.9)a
| 1.1 (0.8–1.6) | 1.6 (1.1–2.4)a
|
Shared needles/syringes | 2.5 (1.3–4.8)a
| 2.3 (1.7–3.2)a
| 1.6 (0.7–4.0) | 1.6 (1.1–2.4)a
|
Lent needles/syringes | 1.0 (0.5–1.9) | 2.4 (1.4–3.9)a
| 0.9 (0.5–1.7) | 1.4 (0.9–1.9) |
Shared paraphernalia | 2.7 (1.4–4.9)a
| 1.8 (1.2–2.7)a
| 2.4 (0.9–6.9) | 1.2 (0.9–1.7) |
Filled from working syringe | 3.6 (2.3–5.8)a
| 1.8 (1.1–3.1)a
| 3.2 (1.4–7.2)a
| 0.7 (0.5–1.1) |
Sexual risk behaviours (last 6 months) | ||||
Any sex in last 6 months | 1.1 (0.6–2.2) | 1.9 (1.1–3.5)a
| 1.5 (1.1–2.2)a
| 0.9 (0.6–1.1) |
≥2 sex partners | 1.2 (0.8–1.8) | 1.7 (1.2–2.4)a
| 1.1 (0.8–1.5) | 1.6 (1.2–2.1)a
|
Regular sex partner injects | 1.5 (0.8–3.2) | 1.9 (0.8–4.4) | 1.2 (0.9–1.6) | 3.2 (2.1–4.9)a
|
Casual sex partner injects | 1.7 (1.0–2.9) | 1.3 (0.5–3.5) | 1.1 (0.5–2.6) | 2.1 (1.1–3.9)a
|
Ever paid for sex | 1.0 (0.4–2.4) | 0.6 (0.2–1.7) | 0.5 (0.2–1.2) | 0.5 (0.1–1.9) |
Serological markersc
| ||||
HIV test positive | 0.7 (0.4–1.3) | 1.1 (0.7–1.8) | 0.9 (0.7–1.3) | 1.3 (0.9–1.8) |
HCV reactive | 0.7 (0.2–2.3) | 0.6 (0.1–2.9) | 0.8 (0.5–1.3) | 0.8 (0.2–4.2) |
HSV positive | 0.6 (0.3–1.1) | 1.1 (0.5–2.8) | 0.6 (0.4–1.0) | 2.0 (0.6–6.6) |
Discussion
Class 1 Polydrug polyroute injection | Class 2 Opiate-stimulant poly-injection | Class 3 Non-injection stimulant co-use | Class 4 Opiate-opioid poly-injection |
---|---|---|---|
– | ↑ <30 years old | ↑ <30 years old | ↑ <30 years old |
↑ non- Russian ethnicity | – | – | ↑ non- Russian ethnicity |
– | – | ↓ Secondary education | – |
– | – | ↑ Non-regular income | – |
– | – | – | – |
↑ Kohtla-Järve | – | ↑ Kohtla-Järve | ↑ St Petersburg |
↑ Frequent injecting | ↑ Frequent injecting | – | =Frequent injecting |
↑ Intense injecting | ↑ Intense injecting | – | ↑ Intense injecting |
↑ Shared needles/syringes | ↑ Shared needles/syringes | – | ↑ Shared needles/syringes |
↑ Sharing paraphernalia | ↑ Sharing paraphernalia | – | – |
↑ Back-loaded | ↑ Back-loaded | ↑ Back-loaded | – |
– | ↑ Any sex last 6 months | ↑ Any sex last 6 months | – |
– | ↑ Multiple sex partners | – | ↑ Multiple sex partners |
– | – | – | ↑ Regular sex partner injects |
– | – | – | ↑ Casual sex partner injects |