Desmond D W, Bagiella E, Moroney J T, Stern Y
Department of Neurology, Columbia University, College of Physicians and Surgeons, New York, NY, USA.
Arch Neurol. 1998 Mar;55(3):390-4. doi: 10.1001/archneur.55.3.390.
Given that prevalence surveys may underestimate the magnitude of the association between an exposure and a disease with high morbidity or mortality, we investigated the effects of patient attrition on estimates of the frequency of dementia following ischemic stroke.
We examined 251 patients 3 months after stroke and diagnosed dementia in 66 (26.3%) based on the results of neuropsychological and functional assessments and modified criteria from the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Those 251 patients were drawn from a larger cohort of 297 patients, with the majority of the remaining 46 patients being unavailable for assessment due to death, severe stroke, or comorbid medical disorders. Using the coefficients in a logistic model of the clinical determinants of dementia based on the 251 patients who were examined, we calculated the probability of dementia for each of the 46 patients who were not examined. We considered a patient to have dementia when that probability was higher than the mean of the median probabilities of dementia in the groups of patients with and without dementia who completed the examinations.
The sensitivity and specificity of our diagnostic method were 75.8% and 72.4%, respectively. We recognized dementia in 21 (45.7%) of the 46 unavailable patients, a significantly higher frequency than among examined patients. Additional analyses determined that the factors that increased the risk of becoming unavailable for follow-up, which included more severe stroke, left and right hemisphere infarct locations, and a history of prior stroke, are similar to the factors that increase the risk of dementia after stroke.
Our findings suggest that dementia is differentially associated with early patient attrition, potentially resulting in the underestimation of its frequency and underrecognition of its importance as an outcome of ischemic stroke.
鉴于患病率调查可能低估高发病率或高死亡率疾病的暴露因素与疾病之间关联的程度，我们研究了患者失访对缺血性卒中后痴呆症发生率估计的影响。
我们在卒中后3个月对251例患者进行了检查，并根据神经心理学和功能评估结果以及《精神障碍诊断与统计手册》第三版修订本中的标准，诊断出66例（26.3%）患有痴呆症。这251例患者来自一个297例患者的更大队列，其余46例患者中的大多数因死亡、严重卒中或合并症而无法进行评估。利用基于接受检查的251例患者的痴呆症临床决定因素逻辑模型中的系数，我们计算了46例未接受检查患者中每例患痴呆症的概率。当该概率高于完成检查的痴呆症患者组和非痴呆症患者组的中位数概率均值时，我们认为该患者患有痴呆症。
我们诊断方法的敏感性和特异性分别为75.8%和72.4%。我们在46例无法评估的患者中识别出21例（45.7%）患有痴呆症，这一频率显著高于接受检查的患者。进一步分析确定，增加失访风险的因素，包括更严重的卒中、左右半球梗死部位以及既往卒中史，与增加卒中后痴呆症风险的因素相似。
我们的研究结果表明，痴呆症与早期患者失访存在差异关联，这可能导致对其发生率的低估以及对其作为缺血性卒中结局重要性的认识不足。
