Recent meta-analysis in schizophrenia report that patients treated with long-acting injectable antipsychotics (LAI) show a significant improvement in hallucinations. However, little evidence supports their efficacy in non-prominent hallucinations in delusional disorder (DD) patients.

To examine treatment effectiveness of LAI antipsychotics (PPLAI and RLAI) with other oral antipsychotics in DD with non-prominent hallucinations.

A prospective and observational study was carried out by including 60 consecutive cases of DD outpatients, as part of the DEVCODEL Study. All patients were followed up for at least 6 months. Outcome variables: Scores in PANSS, HRSD-17 items, PSP for functionality, and C-SSRS for suicide. To investigate whether differences between treatment groups were biased by confounding variables, scores in assessment scales at 6 months served as dependent variables, and hallucinatory and treatment groups were included as between-subject factors when analysis of covariance (ANCOVA) was applied.

24(40%) patients had non-prominent hallucinations. Although not statistically significant, when uncorrected for influencing factors, DD patients receiving PPLAI or RLAI (n=27;45.5%) were less frequently treated with antidepressants (32%vs.68%) and showed lower suicidality (44.4%vs.55.6%). Patients treated with PPLAI or RLAI had lower scores in psychotic symptoms and suicidal ideation intensity, and higher functionality. After adjustment, patients with non-prominent hallucinations receiving PPLAI or RLAI showed a tendency of improvement in functionality, lower scores in PANSS positive (p=0.003) and negative (p=0.047) subscales, and suicidal ideation severity (p<0.001) compared to those treated with oral antipsychotics.

Non-prominent hallucinatory patients treated with PPLAI or RLAI showed a significant improvement in psychopathology and suicidal ideation.