OBJECTIVE To classify a cohort of depressed adolescents recruited to the UK IMPACT trial, according to trajectories of symptom change. We examined for predictors and compared the data-driven categories of patients with a priori operational definitions of treatment response. METHOD Secondary data analysis using growth mixture modelling (GMM). Missing data were imputed. Trajectories of self-reported depressive symptoms were plotted using scores taken at six nominal time points over 86 weeks from randomisation in all 465 patients. RESULTS A piecewise GMM categorised patients into two classes with initially similar and subsequently distinct trajectories. Both groups had a significant decline in depressive symptoms over the first 18 weeks. Eighty-four per cent (84.1%, n = 391) of patients were classed as 'continued-improvers' with symptoms reducing over the duration of the study. A further class of 15.9% (n = 74) of patients were termed 'halted-improvers' with higher baseline depression scores, faster early recovery but no further improvement after 18 weeks. Presence of baseline comorbidity somewhat increased membership to the halted-improvers class (OR = 1.40, CI: 1.00-1.96). By end of study, compared with classes, a clinical remission cut-off score (≤27) and a symptom reduction score (≥50%) indexing treatment response misclassified 15% and 31% of cases, respectively. CONCLUSIONS A fast reduction in depressive symptoms in the first few weeks of treatment may not indicate a good prognosis. Halted improvement is only seen after 18 weeks of treatment. Longitudinal modelling may improve the precision of revealing differential responses to treatment. Improvement in depressive symptoms may be somewhat better in the year after treatment than previously considered.

中文翻译：

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青少年单相重性抑郁症治疗期间和治疗后抑郁症状的变化轨迹。

目的 根据症状变化的轨迹，对招募到英国 IMPACT 试验的抑郁青少年队列进行分类。我们检查了预测因素，并将数据驱动的患者类别与治疗反应的先验操作定义进行了比较。方法 使用生长混合模型 (GMM) 进行二次数据分析。缺失的数据被估算。使用所有 465 名患者随机分组后 86 周内六个标称时间点的分数绘制自我报告的抑郁症状的轨迹。结果 分段 GMM 将患者分为最初相似和随后不同轨迹的两类。在最初的 18 周内，两组的抑郁症状均显着下降。84%（84.1%，n = 391）的患者被归类为“持续改善者” 在研究期间症状减轻。另一类 15.9% (n = 74) 的患者被称为“停止改善者”，其基线抑郁评分较高，早期恢复较快，但 18 周后没有进一步改善。基线合并症的存在在一定程度上增加了停止改进类的成员（OR = 1.40，CI：1.00-1.96）。到研究结束时，与分类相比，指示治疗反应的临床缓解截止评分 (≤27) 和症状减轻评分 (≥50%) 分别错误分类了 15% 和 31% 的病例。结论 在治疗的最初几周内，抑郁症状的快速减轻可能并不表明预后良好。只有在治疗 18 周后才能看到停止的改善。纵向建模可以提高揭示对治疗的不同反应的精度。