Management of older patients with suspected venous thromboembolism

Abstract

To correctly exclude the presence of venous thromboembolism without the need for further diagnostic work-up, so-called diagnostic decision rules -based on a weighed combination of signs and symptoms - have been developed. We performed a prospective validation study of these strategies in frail older out of hospital patients with suspected venous thromboembolism. Venous thromboembolism occurred in 36% of the study participants. This prevalence was much higher than in previous studies in populations of younger adult patients (reporting a prevalence between 7% and 20%) which resulted in a higher probability of venous thromboembolism within the patients with a ‘very low risk’: the failure rate in patients who had a low score on the clinical decision rule and a normal D-dimer test was 6% in our study versus below 2% in previous studies. A normal D-dimer test can rule out venous thromboembolism in patients with a non-high clinical probability according to a clinical decision rule. Since D-dimer levels increase with age, D-dimer testing is less useful to exclude venous thromboembolism in older patients if the conventional cut-off value (500 µg/L) above which the test is considered abnormal is applied.As potential solution of this problem, an age-adjusted cut-off value (age*10 µg/L) in patients >50 years for the D-dimer test was proposed. We validated this age-adjusted D-dimer cut-off value in older primary care patients with suspected deep vein thrombosis. Next, we examined the accuracy of age-adjusted D-dimer levels with a systematic review and bivariate random effects meta-analysis. We found that the proportion of patients with a non-high clinical probability in whom D-dimer testing could exclude venous thromboembolism was only 12.4% in those aged more than 80 years. Application of age-adjusted cut-off values increased the specificity without modifying the sensitivity which remained above 97% in all age categories and would result in correctly avoided imaging examinations in 30 to 42% of patients over 60 years with a non-high probability as compared to 12 to 33% when the conventional cut-off value would be applied. We also focussed on physicians’ considerations in their decision-making to either refer for or to withhold additional diagnostic investigations in nursing home patients. Referral for additional diagnostic investigations was withheld in four out of ten nursing home patientsfor whomimaging examination for suspected venous thromboembolism was indicated (i.e. high-risk patients based on clinical decision rule or D-dimer test). Patients in whom diagnostic investigations were withheld had a higher mortality rate than referred patients, but when adjusted for the probability of being referred (i.e. the propensity score), there was no relation of non-diagnosis decisions to mortality. For a better understanding of the elderly care physicians’ decisions, in-depth interviews were performed and analysed using the grounded theory approach. In their decisions to forgo diagnostic investigations, physicians incorporated the estimated relative impact of the potential disease (the severity of symptoms and the estimated prognosis in the light of the patients’ chronic condition); the potential benefits of diagnostic investigations and whether performing investigations agreed with pre-established management goals in advance care planning.