Understanding the health and service needs of diverse populations of pharmaceutical opioid users: Cohort studies of dependent users in treatment, and people who inject drugs

Background: This technical report summarises and compares the data collected across two time periods from two groups who use pharmaceutical opioids, those seeking treatment for PO dependence and those that inject drugs regularly. Methods: Six local health districts were utilised to recruit the treatment cohort (n=108). The cohort of people who inject drugs (PWID) were recruited through established studies at the National Drug and Alcohol Research Centre (NDARC) and snowballing ( n=133). For the treatment cohort, baseline interviews were conducted between July 2013 and April 2014 and 94% completed a three month follow up interview (n=102). For the PWID cohort, rolling cohort entry occurred between July 2013 and June 2014, and the follow up interview rate was 76%. Data were collected on a range of physical and mental health domains, substance use and treatment experience.

Results: Both cohorts reported high levels of mental and physical health co-morbidity, with a general pattern of more severe physical and mental health problems among the treatment cohort. Substance use was generally stable over the two interviews in both cohorts, with those newer in treatment reporting greater reduction in opioid use in the POUT cohort, and a reduction in oxycodone injection in the PWID cohort.

Conclusions: These studies represent the first Australian studies to examine pharmaceutical opioid use in detail in diverse clinical populations. Findings highlight complexities in treatment presentations with multiple co-morbid health conditions and significant numbers reporting current chronic pain amongst both cohorts. Ongoing monitoring of harms in these cohorts is essential - both cohorts displayed complex clinical profiles. Despite low levels of illicit drug use and injection among the treatrment cohort participants, this cohort typically displayed more severe clinical profiles. Despite this, the treatment cohort reported high levels of retention and low levels of substance use at the follow-up interview, and reported generally positive treatment experiences. Mental health interventions for both these cohorts are warranted.