Lamberts H, Oskam S K, Okkes I M
Academisch Medisch Centrum/Universiteit van Amsterdam, divisie Klinische Methoden & Public Health, afd. Huisartsgeneeskunde, Amsterdam.
Ned Tijdschr Geneeskd. 2005 Nov 12;149(46):2566-72.
To determine how, with the aid of the database of the Transition Project (www.transitionproject.nl), one can calculate posterior probabilities for general practice that provide insight into the clinical significance of the simultaneous occurrence of two events (a symptom and a diagnosis, or two diseases) in general practice.
Descriptive.
The use of the 'International classification of primary care' (ICPC) to code both the patient's reason for encounter and the diagnosis of the general practitioner in the Transition Project has resulted in a database for the period 1985-2002 with a total of 201,127 patient-years, in which the posterior probability of a diagnosis in the presence of a complaint or symptom is available in the form of an odds ratio. Also in the case of the simultaneous occurrence of 2 episodes of care (comorbidity) in a patient it is now possible to determine whether the ratio between the prior and the posterior probability indicates a clinically relevant relationship or that it is a chance finding. Such posterior probabilities have been calculated for the conditions otitis media, hypertension in diabetes mellitus, shortness of breath and heart failure. In the calculation ofthe prior and posterior probabilities, only 'certain' diagnoses were used.
For the diagnosis 'otitis media' in the age group 0-4 years, otalgia had the highest posterior probability (odds ratio: 15.77), with discharge from the ear taking second place (odds ratio: 8.59). 'Fever' contributed almost nothing. The odds ratio for hypertension in 45-74-year-old women with diabetes mellitus was 3.42. When the symptom was 'shortness of breath', the prior probability of heart failure in the age group 45-64 years was relatively low (2.0) but the posterior probability was relatively high (24.2). In this way, the combination of prior and posterior probabilities can provide support for the clinical work of the general practitioner. As a predictive variable for heart failure in the age group 65-74 years, 'ankle oedema' played an important role while 'fatigue' contributed nothing to the diagnosis. It was apparent from the database that the care for patients with heart failure often coincided with that for chronic diseases such as diabetes mellitus, hypertension, ischaemic heart disease, chronic obstructive pulmonary disease and atrial fibrillation. But the question whether there is a clinically relevant relationship could only be answered on the basis of the posterior probabilities: the highest odds ratio's were found for 'atrial fibrillation/atrial flutter' (32.5), 'chronic obstructive pulmonary disease' (22.5) and 'chronic skin ulcer' (20.2).
The calculation of prior and posterior probabilities on the basis of the database of the Transition Project makes it possible for general practitioners to determine the clinical relevance of their observations.
借助过渡项目数据库（www.transitionproject.nl），确定如何计算全科医疗中的后验概率，以深入了解全科医疗中两个事件（一种症状和一种诊断，或两种疾病）同时出现的临床意义。
描述性研究。
在过渡项目中使用“国际初级保健分类法”（ICPC）对患者的就诊原因和全科医生的诊断进行编码，从而形成了一个1985 - 2002年期间的数据库，总计201,127患者年，其中存在某种主诉或症状时诊断的后验概率以比值比的形式提供。对于患者同时出现2次医疗事件（共病）的情况，现在也能够确定先验概率与后验概率之间的比值是否表明存在临床相关关系，或者这只是一个偶然发现。已针对中耳炎、糖尿病合并高血压、呼吸急促和心力衰竭等病症计算了此类后验概率。在计算先验概率和后验概率时，仅使用“确定的”诊断。
对于0 - 4岁年龄组的“中耳炎”诊断，耳痛具有最高的后验概率（比值比：15.77），耳部流脓位居第二（比值比：8.59）。“发热”几乎没有影响。45 - 74岁患有糖尿病的女性中高血压的比值比为3.42。当症状为“呼吸急促”时，45 - 64岁年龄组中心力衰竭的先验概率相对较低（2.0），但后验概率相对较高（24.2）。通过这种方式，先验概率和后验概率的结合可为全科医生的临床工作提供支持。在65 - 74岁年龄组中，作为心力衰竭的预测变量，“踝部水肿”起重要作用，而“疲劳”对诊断没有贡献。从数据库中可以明显看出，对心力衰竭患者的护理常常与糖尿病、高血压、缺血性心脏病、慢性阻塞性肺疾病和心房颤动等慢性病的护理同时出现。但是否存在临床相关关系的问题只能根据后验概率来回答：“心房颤动/心房扑动”（32.5）、“慢性阻塞性肺疾病”（22.5）和“慢性皮肤溃疡”（20.2）的比值比最高。
基于过渡项目数据库计算先验概率和后验概率，使全科医生能够确定其观察结果的临床相关性。
