Pill or needle? Determinants of the preference for long-acting injection over oral treatment in people facing chronic illness.

Although long-acting injection (LAI) is presented as first line treatment option for patients with psychosis, negative attitudes toward this galenic negatively impact the selection of this treatment option. However, these negative attitudes may not be confined to patients but also observed in the general population. A web-based study on 1807 participants was conducted during which participants imagined that they had a particular chronic illness based on clinical vignettes (mental illnesses: schizophrenia, depression; somatic illnesses: multiple sclerosis, rheumatoid arthritis). The frequency of relapse and the intensity of symptoms were experimentally manipulated in the vignettes. Participants rated their subjective distress associated with each vignette, their belief in the effectiveness of treatment, and their treatment preference regarding medication. We examined under which conditions LAI was preferred over pills. Statistical analyses were performed using Bayesian methods. Results showed that participants preferred LAI over pills in 40.5% to 50.8% of cases. LAI was more preferred for illnesses with low frequency of relapse, low subjective distress, and for somatic than for mental illnesses. The perceived advantage for LAI over pills and the belief about the better efficiency of LAI were the main factors that drove the preference for LAI. Keeping in mind some advantages of LAI, the public negative representations of injections might partially influence patients' prejudices against LAI. These attitudes should be named and discussed with the patients when LAI seems to represent a relevant therapeutic option.