The observational retrospective study published online in Addiction estimated retention in OAT, specifically methadone and buprenorphine, and its relationship with person, treatment, and prescriber characteristics in a cohort of 22,577 people entering OAT for the first time in New South Wales, Australia, between 1st August 2001 and 31st December 2015.

Lead author, Ms Chrianna Bharat, a PhD candidate at NDARC, said, “Methadone compared to buprenorphine was associated with improved retention, but this effect varied by the date of first treatment.”

The study found new evidence in factors impacting retention in OAT.

“Being an Aboriginal or Torres Strait Islander person, younger, having a past-year psychotic diagnosis, or having four or more criminal offences in the year prior to treatment were all associated with an increased risk of leaving treatment,” said Ms Bharat.

The study found that most people in the cohort were male (69 per cent) and non-Indigenous (77 per cent), with a median age of 29 years.

“At first OAT entry, the percent of people initiating on methadone reduced over time (74.2 per cent in 2001 to 38.3 per cent in 2015),” said Ms Bharat.

The report also found that people whose prescriber had a longer tenure of OAT prescribing were at a reduced risk of leaving treatment compared to those whose prescribers had less experience.

“An example of this would be a prescriber with three years of OAT prescribing tenure, an increase of five years prescribing experience was associated with a 6 per cent reduction in odds of the person leaving treatment,” said Ms Bharat.

In terms of where a prescriber worked, there was no association found between a person’s time in OAT and either a prescriber’s peer group size or whether they were prescribing from multiple locations.”

Ms Bharat highlighted the need to recognise and address barriers to treatment retention at each of the person, prescriber, and system levels.

“Examining explanations for the improvement in buprenorphine retention over time could help to inform the processes needed to optimise retention, while greater education and mentorship programs could be considered as possible strategies to support prescribers in improving retention of OAT for people prescribed buprenorphine and methadone,” said Ms Bharat.

Professor Michael Farrell, Director of NDARC said, “this important long-term study highlights improved treatment retention with buprenorphine which may be related to experienced clinicians’ skill fully inducting patients onto buprenorphine.”

Read the full paper here