Predictors of poor health and heroin use in methadone-treated injecting heroin users: The importance of methadone dosage and crack cocaine use
Felicia Heidebrecht, Jenny Corless, Mary Bell Macleod and Lynne Dawkins
Methadone is used world-wide as a first choice treatment for opioid dependency, and higher doses are generally associated with higher rates of treatment retention and heroin abstinence. However, methadone also poses risks in combination with other depressant drugs, especially at higher doses, the most critical being respiratory overdose. Research suggests that heroin use in methadone treatment is more common for dual users of heroin and crack/cocaine. In addition, more frequent intravenous (IV) use and poor technique increase the risk of health complications. Dual users injecting drugs might therefore be at higher risk of physical health deterioration, especially when prescribed higher doses of methadone.
The aim of this study was to explore the physical health, hepatitis C status and heroin use of IV drug users in methadone treatment by comparing high (≥70 mg daily) vs. low (<70 mg daily) doses, and the route of crack administration.
Study design: Retrospective study
Participants: Current or previous intravenous users of heroin in methadone treatment in two services in London, UK
Sample characteristics: N=255, mean age 45.8 ± 9 years; 78.0 % male;
Data collection: clinical records;
Predictors: methadone dose, alcohol use, crack use, crack injection, mental health, combined duration of drug use and treatment;
Outcomes: IV use-related physical health, hepatitis C infection, current heroin use;
Statistical analyses: Chi square, t tests, logistic regressions.
Sample characteristics: N=36, mean age 46.5 ± 8.0 years; 75.0 % male;
Data collection: clinical records and face-to-face interviews covering the history of drug use, treatment, living situation and physical health;
Predictors: methadone dose, alcohol use, crack injection, mental health, duration of crack use, duration of heroin use, duration of methadone treatment, total duration of IV use, duration of IV use while in treatment, use of high-risk injection sites (groin, neck), cardiovascular risk, homelessness, injecting technique;
Outcome: IV use-related physical health;
Statistical analyses: Chi square, t tests, bivariate associations.
The combined duration of drug use and treatment (OR=1.06, 95% CI: 1.03–1.09), frequent alcohol use (OR=1.92, 95% CI: 1.02–3.61), intravenous crack use (OR=3.29, 95% CI: 1.85–5.86) and high dose of methadone ( OR=1.82, 95% CI: 1.06–3.13) correlated positively with poor physical health.
The duration of drug use and treatment correlated negatively with heroin use (OR=0.97, 95% CI: 0.94-0.99). Higher dose of methadone predicted heroin abstinence only for those not using crack (OR=10.60, 95% CI: 2.28-49.15). On high dose participants with a mental health condition were less likely to use heroin, whereas on low dose the opposite was found (OR=0.12, 95% CI: 0.03-0.49).
The combined duration of drug use and treatment (OR=1.06, 95% CI: 1.03-1.09) and the intravenous use of crack ( OR=2.34, 95% CI: 1.31- 4.16) correlated positively with hepatitis C infection.
Compared to low dose, more participants on high dose experienced frequent overdoses (47% vs. 24%), and used high-risk injection sites (groin, neck) (67% vs 24%). Their most frequent reason for stopping IV use was due to difficulty finding veins on a high-risk site, or a related severe health complication, whereas many participants on low dose switched to smoking when not able to find veins at lower-risk sites.
Duration of treatment (OR=1.16, 95% CI: 1.04–1.29) but not of drug use, high methadone dose (OR=5.50, 95% CI: 1.23–23.69), duration of IV use while in treatment (OR=1.33, 95% CI: 1.88–1.63), and the use of high risk injection sites ( OR=10.0, 95% CI: 2.06–48.56) were positively associated with poor health. Cardiovascular risk, homelessness and injecting technique did not predict poor health.
For the majority of those participants who transitioned to high-risk injecting sites and/or experienced severe physical health complications, those events took place after the start of the first methadone treatment episode.
Although high doses of methadone have been associated with better treatment retention and heroin abstinence, this study shows that
a) dosage can affect a range of outcomes in different ways and
b) there may be important individual differences that need to be taken into consideration when optimizing methadone dosage such as crack use and injecting, alcohol use and mental health.