Heightened clinical suspicion of pulmonary embolism and disregard of the D-dimer assay: a contemporary trend in an era of increased access to computed tomography pulmonary angiogram?

BACKGROUND: Prospective studies have shown that utilising qualitative D-dimers in those with a low Wells pre-test probability (PTP) of pulmonary embolism (PE) have significantly reduced the number of computed tomography pulmonary angiograms (CTPA) being performed. These studies have been based on a PE prevalence of approximately 6% in the low PTP group. AIM: This study compares the diagnostic approach to PE in the study institution to well-established guidelines. The study also re-examines the cost-benefit analyses of qualitative d-dimers and CTPA in the low PTP group. METHODS: A retrospective study of 169 consecutive CTPA requested in the emergency department of a major teaching hospital during a 12-month period. RESULTS: The prevalence of PE was 0% (0/65), 11.7% (9/77) and 0% (0/2) in the low, moderate and high Wells PTP groups respectively, and 6.3% (9/144) overall. PTP was documented in 10 (6.9%) cases, and the qualitative Clearview Simplify D-dimer was only ordered in 33.8% (22/65) of low PTP subjects. The false positive D-dimer rate was 90.2% (37/41). Cost-benefit analysis and assay performance defines a narrow range of low PTP PE prevalence between 1% and 5% for the utilisation of the qualitative D-dimer assay. CONCLUSIONS: The overall prevalence of PE in subjects undergoing CTPA was significantly lower compared with data in the literature. The authors recommend warranted clinical suspicion of PE should be confirmed by a senior physician prior to placing a patient in the PE work-up pathway. In such patients, the qualitative D-dimer assay should be utilised if PTP is low, and the exclusionary efficiency of the D-dimer will be improved in the setting of higher PE prevalence in this subgroup. Hospitals should audit local PE prevalence, as cost-benefit analyses raises questions about the effectiveness of D-dimers when PE prevalence is very low in the low PTP subgroup.

Detecting patients with Alzheimer's disease suitable for drug treatment: comparison of three methods of assessment.

BACKGROUND: Therapy to enhance cholinergic function in the brain is under evaluation for the treatment of Alzheimer's disease. Tetrahydroaminoacridine (tacrine) has recently received a product licence in the United States of America for the treatment of Alzheimer's disease, and the licence application in the United Kingdom will shortly be reviewed. It is therefore possible that this drug will become available for use in the UK in due course. There will then be a need for screening procedures for a large number of elderly patients to decide whether or not they have dementia and, if so, whether it is the result of Alzheimer's disease and is suitable for treatment with the new drug. METHOD: A total of 246 patients aged 75 years or over in two general practices in Bristol were assessed to investigate the potential workload such screening would engender. Three different assessment schedules for the diagnosis of dementia were compared--the mini-mental state examination, the Kew test, and the abbreviated mental test score. RESULTS: None of the assessment schedules was found to be particularly onerous, with median times for administration of five, three and two minutes, respectively. A score of 23 or less on the mini-mental state examination was taken as the main cut-off point for further evaluation. Sixty six patients obtained this score--in 25 the low score reflected factors other than dementia, and 11 others declined further assessment. Of the remaining 30 patients only four had probable Alzheimer's disease at an appropriate level of severity for treatment, and lived with a carer who could ensure compliance and monitor side effects. Two of these patients were receiving conflicting medical treatment and a third declined therapy, leaving only one person for whom treatment could be prescribed. CONCLUSION: It seems likely that of those medically suitable for treatment, it may not be possible to prescribe tacrine for an appreciable proportion. Nevertheless, all potential patients should be screened as the procedures involved are not onerous and at least some of those found suitable for treatment are likely to benefit from this new approach.