Mono- and poly-therapy with benzodiazepines or Z-drugs: Results from a tertiary-care Addiction Unit study

Background: Using benzodiazepines (BZDs) or Z-drugs in poly-therapy is a critical issue. Objective: Identifying factors influencing the use of BZDs/Z-drugs in poly- vs mono-therapy in patients with or without substance use disorders (SUDs). Methods: 986 inpatients were analysed. Socio-demographic and clinical variables were collected. BZD/Z-drug doses were compared via the Defined Daily Dose (DDD) and standardized as diazepam dose equivalents. Mann-Whitney, Chi-square, Fisher test, hierarchical multivariate regression analyses were run referring to the whole sample and to subjects with current SUDs, lifetime SUDs, current and lifetime SUDs, non-SUDs. Results: In the whole sample the variance of being mono- vs poly-therapy users was explained by BZD/Z-drug formulation, DDD, duration of treatment, age of first BZDs/Z-drugs use (ΔR2 = 0.141, p < 0.001). Among those with current SUDs (ΔR2 = 0.278, p = 0.332) or current and lifetime SUDs (ΔR2 = 0.154, p = 0.419), no variables explained the variance of being mono-vs poly-therapy users. Among lifetime SUDs subjects, the variance of being mono- vs poly-therapy users was explained by BZD/Z-drug formulation and age of first BZD/Z-drug use (ΔR2 = 0.275, p < 0.001). Among non-SUDs subjects, the variance of being mono- vs poly-therapy users was explained by DDD and duration of treatment (ΔR2 = 0.162, p = 0.001). Conclusions: Tablets, high drug doses, long duration of treatment, and early age of first use were more likely associated to poly- than mono-therapy. This suggests that patients have different clinical features and a pharmacological prescription should be tailored to them also based on the variables here analysed.