Predicting Fatal Drug Poisoning Among People Living with HIV-HCV Co-Infection.

BACKGROUND

Drug poisoning (overdose) is a public health crisis, particularly among people living with HIV and hepatitis C (HCV) co-infection. Identifying potential predictors of drug poisoning could help decrease drug-related deaths.

METHODS

Data from the Canadian Co-infection Cohort were used to predict death due to drug poisoning within 6 months of a cohort visit. Participants were eligible for analysis if they ever reported drug use. Supervised machine learning (stratified random forest with undersampling to account for imbalanced data) was used to develop a classification algorithm using 40 sociodemographic, behavioural, and clinical variables. Predictors were ranked in order of importance, and odds ratios and 95% confidence intervals (CIs) were generated using a generalized estimating equation regression.

RESULTS

Of 2,175 study participants, 1,998 met the eligibility criteria. There were 94 drug poisoning deaths, 53 within 6 months of a last visit. When applied to the entire sample, the model had an area under the curve (AUC) of 0.9965 (95% CI, 0.9941-0.9988). However, the false-positive rate was high, resulting in a poor positive predictive value (1.5%). Our model did not generalize well out of sample (AUC 0.6, 95% CI 0.54-0.68). The top important variables were addiction therapy (6 months), history of sexually transmitted infection, smoking (6 months), ever being on prescription opioids, and non-injection opioid use (6 months). However, no predictor was strong.

CONCLUSIONS

Despite rich data, our model was not able to accurately predict drug poisoning deaths. Larger datasets and information about changing drug markets could help improve future prediction efforts.