van Loo Hanna M, Schoevers Robert A, Kendler Kenneth S, de Jonge Peter, Romeijn Jan-Willem
Interdisciplinary Center Psychopathology and Emotion Regulation (ICPE), Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, Virginia.
Depress Anxiety. 2016 Feb;33(2):143-52. doi: 10.1002/da.22453. Epub 2015 Dec 1.
High rates of psychiatric comorbidity are subject of debate: To what extent do they depend on classification choices such as diagnostic thresholds? This paper investigates the influence of different thresholds on rates of comorbidity between major depressive disorder (MDD) and generalized anxiety disorder (GAD).
Point prevalence of comorbidity between MDD and GAD was measured in 74,092 subjects from the general population (LifeLines) according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) criteria. Comorbidity rates were compared for different thresholds by varying the number of necessary criteria from ≥ 1 to all nine symptoms for MDD, and from ≥ 1 to all seven symptoms for GAD.
According to DSM thresholds, 0.86% had MDD only, 2.96% GAD only, and 1.14% both MDD and GAD (odds ratio (OR) 42.6). Lower thresholds for MDD led to higher rates of comorbidity (1.44% for ≥ 4 of nine MDD symptoms, OR 34.4), whereas lower thresholds for GAD hardly influenced comorbidity (1.16% for ≥ 3 of seven GAD symptoms, OR 38.8). Specific patterns in the distribution of symptoms within the population explained this finding: 37.3% of subjects with core criteria of MDD and GAD reported subthreshold MDD symptoms, whereas only 7.6% reported subthreshold GAD symptoms.
Lower thresholds for MDD increased comorbidity with GAD, but not vice versa, owing to specific symptom patterns in the population. Generally, comorbidity rates result from both empirical symptom distributions and classification choices and cannot be reduced to either of these exclusively. This insight invites further research into the formation of disease concepts that allow for reliable predictions and targeted therapeutic interventions.
精神疾病共病率较高一直是个有争议的话题：它们在多大程度上取决于诸如诊断阈值等分类选择？本文研究了不同阈值对重度抑郁症（MDD）和广泛性焦虑症（GAD）共病率的影响。
根据《精神疾病诊断与统计手册》（DSM-IV-TR）标准，对来自普通人群（生命线研究）的74092名受试者测量了MDD和GAD的共病点患病率。通过将MDD所需标准数量从≥1个症状变化到全部9个症状，以及将GAD所需标准数量从≥1个症状变化到全部7个症状，比较了不同阈值下的共病率。
根据DSM阈值，仅患有MDD的占0.86%，仅患有GAD的占2.96%，同时患有MDD和GAD的占1.14%（优势比（OR）为42.6）。MDD较低的阈值导致共病率更高（9个MDD症状中≥4个症状时为1.44%，OR为34.4），而GAD较低的阈值对共病率几乎没有影响（7个GAD症状中≥3个症状时为1.16%，OR为38.8）。人群中症状分布的特定模式解释了这一发现：符合MDD和GAD核心标准的受试者中，37.3%报告有阈下MDD症状，而只有7.6%报告有阈下GAD症状。
由于人群中特定的症状模式，MDD较低的阈值增加了与GAD的共病率，但反之则不然。一般来说，共病率既源于经验性的症状分布，也源于分类选择，不能仅仅归结于其中任何一个因素。这一见解促使人们进一步研究疾病概念的形成，以便进行可靠的预测和有针对性的治疗干预。
