Abstract The aim of this study was to describe and explain the prevalence and reasons for as needed medication (pro re nata, PRN) in a forensic psychiatric hospital. We reviewed the documents of 67 long-term inpatients (87% male) over the one-year study period and identified 8626 PRN events. Virtually all of the patients received PRN for physical reasons, just over half for psychiatric reasons, and just over one-third for insomnia. The number of PRN events per patient was unevenly distributed. The prevalence of PRN events for both psychiatric reasons (26%) and insomnia (14%) were associated with the female gender, more severe psychiatric symptoms, and lower daily functioning. Half of the patients did not receive PRN for psychiatric reasons. It is likely that the use of such medication was successfully mitigated with scheduled medication and psychosocial approaches. The high number of PRN events for physical reasons (60%) was not explained by the patient characteristics and urgent research is needed on this aspect. Protracted PRN use should be recognized in clinical practice, and consider more structured solutions to develop PRN protocols and evidence-based care. Future research should examine how PRN is integrated with patients’ regular treatment and non-pharmacological methods.

中文翻译：

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法医精神病医院的PRN药物事件：发生率和原因的文献分析

摘要这项研究的目的是描述和解释法医精神病医院按需药物治疗（普遍使用PRN）的发生率和原因。我们回顾了一年研究期间67例长期住院患者（男性占87％）的文献，并确定了8626例PRN事件。几乎所有患者由于身体原因接受PRN，因精神原因仅接受一半以上，因失眠而接受三分之一以上。每个患者的PRN事件数量分布不均。出于精神原因（26％）和失眠（14％）的PRN事件的患病率与女性，更严重的精神症状和较低的日常功能有关。一半的患者由于精神病原因未接受PRN。计划的药物治疗和社会心理方法有可能成功减轻此类药物的使用。由于身体原因，PRN事件的高发生率（60％）并未得到患者特征的解释，因此需要对此方面进行紧急研究。长期使用PRN应当在临床实践中得到认可，并考虑采用更结构化的解决方案来开发PRN方案和循证护理。未来的研究应检查PRN如何与患者的常规治疗和非药物方法相结合。并考虑采用更结构化的解决方案来开发PRN协议和循证护理。未来的研究应检查PRN如何与患者的常规治疗和非药物方法相结合。并考虑采用更结构化的解决方案来开发PRN协议和循证护理。未来的研究应检查PRN如何与患者的常规治疗和非药物方法相结合。