A systematic review and meta-analysis has estimated that the incidence of iatrogenic opioid dependence or abuse in patients prescribed opioids for pain is almost 1 in 20.

Researchers from the University of Dundee carried out systematic searches of six online databases (Embase, Medline, PubMed, Cinahl Plus, Web of Science, and OpenGrey) to find relevant studies. A ‘grey’ literature search and a manual reference search of included articles were also undertaken.

The study’s objective was to estimate the incidence of iatrogenic opioid dependence or abuse in patients with pain who had been prescribed opioid analgesic therapy.

After reviewing more than 3,000 papers, 12 studies, judged as good or fair quality, that met the inclusion criteria were chosen for analysis.

These studies covered a total of 310,408 participants. There was little within-study risk for bias, and no significant publication bias was identified. The main measure used was the event rate i.e. the proportion of the total population developing dependence or abuse.

A random effects model (DerSimonian-Laird method) for data analysis provided a pooled incidence of opioid dependence or abuse of 4.7%. However, the authors did note substantial heterogeneity among study effects and the incidence ranged from 0.2% to 34.2%.

Sensitivity analyses indicated that the diagnostic criteria used for opioid dependence or abuse (i.e. differences between DSM-IV and ICD-9 criteria) accounted for 20% of this variance in study effects and length of exposure to opioid analgesics accounted for a further 18%. Studies deemed of good quality were associated with a significantly lower incidence (3.1%) than those of fair quality (15.1%).

Strong opioids were associated with a significantly lower incidence (0.7%) than weak opioids (5.5%). Rates of dependence and abuse were found to be lower among those prescribed opioids for a longer period, 3 months or more (2.3%), than in those prescribed opioids for a varied period (10.7%).

Prescribing of opioids in the management of chronic non-cancer pain has been increasing in recent years, and prescribers need to balance their desire to provide relief from pain against the risks of contributing to physical dependence, addiction and diversion of prescribed opioids.

This paper provides useful additional information that will assist in getting the balance right.

The study authors caution that differences in aetiology, pain severity or the nature of the pain may account for these counter-intuitive findings.

They conclude: ‘There is a need for well designed, rigorously controlled, adequately powered prospective experimental studies examining the incidence – rather than prevalence –

of iatrogenic opioid dependence and abuse after analgesic prescribing.’

Dr Jez Thompson

Higgins C, Smith BH, Matthews K. Incidence of iatrogenic opioid dependence or abuse in patients with pain who were exposed to opioid analgesic therapy: a systematic review and meta-analysis. Br J Anaesthesia 2018;120(6):1335-44