Objective: To determine the relationship between treatment duration and the efficacy of pharmacological treatment for reducing ADHD symptoms. Method: We conducted a systematic review of randomized, double-blind, placebo-controlled clinical trials investigating the efficacy of pharmacological interventions in patients with ADHD. The last bibliographic search was performed in April 15, 2019. The effect of treatment duration on efficacy was studied using meta-regression. Results: A total of 87 studies lasting from 3 to 28 weeks were included. Pharmacological treatment improved ADHD symptom severity by -7.35 points. Treatment duration did not moderate the efficacy of pharmacological treatment. Consistent results were found for psychostimulant drugs, methylphenidate, amphetamine derivatives, atomoxetine, and α2-agonists. A negative correlation was found between baseline ADHD severity efficacy (Coefficient = -.250, p = .013). Conclusion: The efficacy of pharmacological treatment for ADHD remains stable over time. A greater efficacy in more severe patients is suggested.

中文翻译：

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ADHD 药物治疗持续时间与疗效的关系：87 项随机对照临床试验的元分析和元回归。

目的：确定治疗持续时间与减轻多动症症状的药物治疗效果之间的关系。方法：我们对随机、双盲、安慰剂对照的临床试验进行了系统评价，这些试验调查了药物干预对 ADHD 患者的疗效。最后一次书目检索于 2019 年 4 月 15 日进行。使用元回归研究治疗持续时间对疗效的影响。结果：共纳入 87 项持续 3 至 28 周的研究。药物治疗使 ADHD 症状的严重程度提高了 -7.35 分。治疗持续时间不会影响药物治疗的疗效。精神兴奋剂、哌甲酯、苯丙胺衍生物、托莫西汀和α2-激动剂的结果一致。在基线 ADHD 严重程度疗效之间发现负相关（系数 = -.250，p = .013）。结论：药物治疗多动症的疗效随着时间的推移保持稳定。建议对更严重的患者有更大的疗效。