Sethi D, Wheeler J, Rodrigues L C, Fox S, Roderick P
MRC Epidemiology and Medical Care Unit, Wolfson Institute of Preventive Medicine, St Bartholomew's and the Royal London Hospital School of Medicine and Dentistry, UK.
Int J Epidemiol. 1999 Feb;28(1):106-12. doi: 10.1093/ije/28.1.106.
One of the aims of the Study of Infectious Intestinal Disease (IID) in England is to estimate the incidence of IID presenting to general practice. This sub-study aims to estimate and correct the degree of under-ascertainment in the national study.
Cases of presumed IID which presented to general practice in the national study had been ascertained by their GP. In 26 general practices, cases with computerized diagnoses suggestive of IID were identified retrospectively. Cases which fulfilled the case definition of IID and should have been ascertained to the coordinating centre but were not, represented the under-ascertainment. Logistic regression modelling was used to identify independent factors which influenced under-ascertainment.
The records of 2021 patients were examined, 1514 were eligible and should have been ascertained but only 974 (64%) were. There was variation in ascertainment between the practices (30% to 93%). Patient-related factors independently associated with ascertainment were: i) vomiting only as opposed to diarrhoea with and without vomiting (OR 0.37) and ii) consultation in the surgery as opposed to at home (OR 2.18). Practice-related factors independently associated with ascertainment were: i) participation in the enumeration study component (OR 1.78), ii) a larger number of partners (OR 0.3 for 7-8 partners); iii) rural location (OR 2.27) and iv) previous research experience (OR 1.92). Predicted ascertainment percentages were calculated according to practice characteristics.
Under-ascertainment of IID was substantial (36%) and non-random and had to be corrected. Practice characteristics influencing variation in ascertainment were identified and a multivariate model developed to identify adjustment factors which could be applied to individual practices. Researchers need to be aware of factors which influence ascertainment in acute epidemiological studies based in general practice.
英国感染性肠道疾病研究（IID）的目标之一是估计全科医疗中感染性肠道疾病的发病率。这项子研究旨在估计并纠正全国性研究中漏报的程度。
在全国性研究中，全科医疗中疑似感染性肠道疾病的病例由其全科医生确定。在26家全科诊所中，对计算机诊断提示感染性肠道疾病的病例进行回顾性识别。符合感染性肠道疾病病例定义且本应上报至协调中心但未上报的病例，代表了漏报情况。采用逻辑回归模型来识别影响漏报的独立因素。
检查了2021名患者的记录，其中1514名符合条件且本应上报，但只有974名（64%）被上报。各诊所之间的上报情况存在差异（30%至93%）。与上报独立相关的患者因素为：i）仅呕吐而非伴有或不伴有呕吐的腹泻（比值比0.37），以及ii）在诊所就诊而非在家就诊（比值比2.18）。与上报独立相关的诊所因素为：i）参与计数研究部分（比值比1.78），ii）更多的合伙人数量（7 - 8名合伙人时比值比0.3）；iii）农村地区（比值比2.27）以及iv）既往研究经验（比值比1.92）。根据诊所特征计算预测上报百分比。
感染性肠道疾病的漏报情况严重（36%）且非随机，必须加以纠正。识别了影响上报差异的诊所特征，并开发了一个多变量模型来识别可应用于各个诊所的调整因素。研究人员需要意识到在基于全科医疗的急性流行病学研究中影响上报的因素。
