Retention of participants in opiate substitution programs in low and middle-income countries: An international systematic review

Background: Opiate substitution therapy (OST) is a key component in overdose prevention, reducing opiate use and risk of blood borne virus infection. By retaining participants in OST programs for longer periods of time, more permanent changes in drug use and risk behavior can be achieved. Studies in high income countries have established a 50% average12-month follow-up retention rate as an indicator of a successful OST program. However, we do not have the same systematic understanding of OST program participant retention in low and middle-income countries (LMIC).

Methods: Utilizing PRISMA guidelines we conducted a systematic review to identify OST program studies that measured retention, over time, for participants in OST programs in LMIC. Retention was measured for participants by length of follow-up, type of OST treatment, and OST dosage.

Results: A total of 58 OST program studies were included in the review. Overall average retention after 12 months was 54.3%. Overall average retention was moderately good for both buprenorphine (48.3%) and methadone (56.6%), after 12 months of treatment. Among programs utilizing methadone, there was no statistically significant difference in average retention by dosage level, and the ten highest and lowest dosage programs obtained similar average retention levels after 12 months.

Conclusion: LMIC have successfully achieved the average 50% retention minimum among OST participants after 12 months, and average retention in LMIC is comparable to established OST programs in high-income countries. These results are promising, as higher retention over time is associated with greater changes in drug use and associated risky behaviors.