We are happy to clarify. Of the 667 patients, 265 opioid-dependent patients entered in-patient treatment for induction onto agonist maintenance treatment and were therefore excluded. Also, patients who left their respective clinics prematurely were not eligible for participation (n = 193); 11 were excluded owing to psychotic symptoms, 8 owing to pregnancy, and 17 owing to extreme ALT/AST values.

This left 173 opioid-dependent patients satisfying inclusion criteria. However, the virtually complete novelty of naltrexone implant treatment in Norway at the time of recruitment probably means that these results are a poor basis upon which to base estimates of demand for this form of treatment.

The randomised trial period was followed by an implantation or re-implantation opportunity for all patients, meaning that the proportion of patients who entered in-patient treatment again at the end of the study to detoxify or stabilise is probably higher than it would be in future clinical samples. Reporting it as a result or as part of a figure could be regarded as misleading.