The characteristics of people who inject drugs in the United Kingdom: changes in age, duration, and incidence of injecting, 1980–2019, using evidence from repeated cross‐sectional surveys
Bibliographic record
Abstract
BACKGROUND AND AIMS: Mortality and drug treatment data suggest that the median age of people who inject drugs is increasing. We aimed to describe changes in the characteristics of people injecting drugs in the United Kingdom (UK). DESIGN: Repeat cross-sectional surveys and modelling. SETTING: Low-threshold services in the United Kingdom such as needle and syringe programmes. PARTICIPANTS: A total of 79 900 people who recently injected psychoactive drugs in the United Kingdom, recruited as part of the Unlinked Anonymous Monitoring Survey (England, Wales, Northern Ireland, 1990-2019) and Needle Exchange Surveillance Initiative (Scotland, 2008-2019). MEASUREMENTS: Age of people currently injecting, age at first injection, duration of injecting (each 1990-2019) and estimates of new people who started injecting (1980-2019). FINDINGS: In England, Wales and Northern Ireland between 1990 and 2019, the median age of people injecting increased from 27 (interquartile range [IQR], 24-31) to 40 (IQR, 34-46); median age at first injection increased from 22 (IQR, 19-25) to 33 (IQR, 28-39); and median years of injecting increased from 7 (IQR, 3-11) to 18 (IQR, 9-23). Values in Scotland and England were similar after 2008. The estimated number that started injecting annually in England increased from 5470 (95% prediction interval [PrI] 3120-6940) in 1980 to a peak of 10 270 (95% PrI, 8980-12 780) in 1998, and then decreased to 2420 (95% PrI, 1320-5580) in 2019. The number in Scotland followed a similar pattern, increasing from 1220 (95% PrI, 740-2430) in 1980 to a peak of 3080 (95% PrI, 2160-3350) in 1998, then decreased to a 270 (95% PrI, 130-600) in 2018. The timing of the peak differed between regions, with earlier peaks in London and the North West of England. CONCLUSIONS: In the United Kingdom, large cohorts started injecting psychoactive drugs in the 1980s and 1990s and many still inject today. Relatively few people started in more recent years. This has led to changes in the population injecting drugs, including an older average age and longer injecting histories.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".