Model-based evaluation and optimization of cardiac monitoring protocols for adjuvant treatment of breast cancer with trastuzumab.

PURPOSE: Trastuzumab treatment is associated with occurrence of cardiac toxicity, for which monitoring of the left ventricular ejection fraction (LVEF) is indicated. The performance of the currently used monitoring protocol as defined in the summary of product characteristics (SPC) is however unknown. The objective of this analysis was to develop a model-based framework for evaluation and optimization of cardiac monitoring strategies. METHODS: The model-based framework comprised a previously developed exposure-response model for trastuzumab induced changes in LVEF, and a protocol-execution model that allowed incorporation of treatment interventions as described by a monitoring protocol. Metrics for evaluation of toxicity, dose intensity and monitoring burden were defined to allow evaluation and optimization of cardiac monitoring protocols. RESULTS: The success of a protocol-defined dose reduction was improved from 40% for the SPC-based protocol, to 79% for a scoring-based protocol, thereby decreasing the observed severity of cardiotoxicity. Including adaptation based on risk-profile allowed reduction of the mean number of LVEF measurements by 19%. CONCLUSIONS: This model-based evaluation approach enabled evaluation and optimization of cardiac monitoring protocols that would be difficult to evaluate in a clinical setting. This approach can potentially be applied for other drugs that use repeated evaluation of continuous biomarkers for toxicity.

A model of hypertension and proteinuria in cancer patients treated with the anti-angiogenic drug E7080.

Hypertension and proteinuria are commonly observed side-effects for anti-angiogenic drugs targeting the VEGF pathway. In most cases, hypertension can be controlled by prescription of anti-hypertensive (AH) therapy, while proteinuria often requires dose reductions or dose delays. We aimed to construct a pharmacokinetic-pharmacodynamic (PK-PD) model for hypertension and proteinuria following treatment with the experimental VEGF-inhibitor E7080, which would allow optimization of treatment, by assessing the influence of anti-hypertensive medication and dose reduction or dose delays in treating and avoiding toxicity. Data was collected from a phase I study of E7080 (n = 67), an inhibitor of multiple tyrosine kinases, among which VEGF. Blood pressure and urinalysis data were recorded weekly. Modeling was performed in NONMEM, and direct and indirect response PK-PD models were evaluated. A previously developed PK model was used. An indirect response PK-PD model described the increase in BP best, while the probability of developing proteinuria toxicity in response to exposure to E7080, was best described by a Markov transition model. This model may guide clinical interventions and provide treatment recommendations for E7080, and may serve as a template model for other drugs in this class.

Contraindications for anticoagulation in older patients with atrial fibrillation; a narrative review.

BACKGROUND: Oral anticoagulation (OAC) is the most effective treatment to prevent strokes in patients with atrial fibrillation (AF). Many older patients are not prescribed OAC. OBJECTIVE: To explore which co-morbid conditions in older patients with AF have been associated with under-treatment with OAC, or were used as exclusion criteria for trials, or have been associated with increased risk of bleeding. METHODS: A Pubmed search was conducted with the terms elderly, atrial fibrillation, stroke risk, bleeding risk, intracranial haemorrhage, cognition, fall risk, renal dysfunction, alcohol abuse, malignancy, polypharmacy, NSAID, under-treatment, under-use and under-prescription. RESULTS: Higher age is associated with under-treatment. Patients with a higher risk of stroke show higher rates of bleeding complications. The associations of bleeding rates with possible contraindications are inconsistent. DISCUSSION: Published bleeding rates reflect selection bias, describing mainly relatively healthy older patients. The use of stratification schemes for stroke risk and for bleeding risk will have to be implemented. CONCLUSION: The decision to prescribe OAC in older patients with AF remains a challenging task since bleeding risk is difficult to estimate reliably. Stratification schemes may be helpful.

Reasons for undertreatment with oral anticoagulants in frail geriatric outpatients with atrial fibrillation: a prospective, descriptive study.

OBJECTIVES: The main aims of the study were to explore whether oral anticoagulation (OAC) for atrial fibrillation (AF) in geriatric outpatients is prescribed in accordance with international (American College of Cardiology/American Heart Association/European Society of Cardiology [ACC/AHA/ESC]) and Dutch national guidelines for the general practitioner (GP) and to identify whether age and selected co-morbid conditions are associated with undertreatment. As a secondary objective, we wanted to establish how many patients discontinue OAC because of major bleeding. METHODS: In 2004, at the first visit of all patients to the geriatric day clinic of the Slotervaart Hospital in Amsterdam, the Netherlands, demographic data, Mini-Mental State Examination score, medical history, Charlson Comorbidity Index score, and data on medication use and changes were documented. The presence of AF was established by assessment of medical history information obtained by the GP, the history taken from patients and their caregivers, and the results of clinical evaluation, including ECG findings. Associations between the use of OAC, demographic data and co-morbid conditions registered in the Dutch NHG (Nederlands Huisartsen Genootschap [Dutch College of General Practitioners]) standard for GPs as risk factors for stroke or contraindications to the use of OAC were analysed. The reasons for discontinuing OAC were assessed after 4 years by requesting the information from the anticoagulation services or the GP. RESULTS: At the time of the initial visit, 17.5% of the 807 outpatients had chronic AF (n = 135) or were known to have paroxysmal AF (n = 6). The mean age of the 141 patients in this cohort was 84.3 years (SD 6.2 years). Co-morbid conditions increasing the risk of stroke were present in 129 patients (91.5%). Contraindications to the use of OAC were observed in 118 patients (83.7%). Of the 116 patients with AF in their history before their visit, 57.8% were being treated with OAC at the time of their visit. After comprehensive geriatric assessment, 73 (51.8%) of the 141 patients with chronic or paroxysmal AF were continued on OAC. Of the 141 patients with chronic or paroxysmal AF, 110 (78.0%) had both extra stroke risk factors and contraindications to the use of OAC. Only increasing age was significantly and independently associated with not being prescribed anticoagulants (p < 0.001). At the 4-year follow-up, OAC had been discontinued in 5.5% of patients because of major bleeding; three patients (4.1%) taking OAC had died as a result of major bleeding, and one other patient had discontinued treatment because of a major, non-lethal bleeding episode. CONCLUSION: Applying the NHG standard for appropriate prescription, and disregarding age as a risk factor or contraindication, in this population, 14 of 141 patients (9.9%) were inappropriately prescribed OAC, salicylates or no prophylaxis. Since only patient age was associated with not prescribing OAC in this study, higher age still seems to be considered the most important contraindication to anticoagulation therapy. Implementation of better models for stratifying bleeding risk in the frail elderly is needed. After 4 years, the cumulative rate of bleeding causing discontinuation of anticoagulation therapy in this usual-care study of frail older patients was not alarmingly higher than in other usual-care studies.

Treatment of hypertension in an elderly outpatient population in the Netherlands.

BACKGROUND: The treatment of older patients with hypertension has been controversial-in addition to uncertainty regarding appropriate blood pressure (BP) targets in the very old, there are concerns that excessive BP lowering could result in adverse events such as falls, stroke, and cognitive problems. The Hypertension in the Very Elderly Trial (HYVET), however, found that lowering BP in patients aged > or =80 years was associated with decreased morbidity and mortality. OBJECTIVE: This study compared the findings of HYVET with data from a population of elderly outpatients with hypertension in a clinical practice setting. METHODS: This was a retrospective study of prospectively collected data from patients aged > or =80 years with a history of hypertension who visited a geriatric diagnostic day clinic in the Netherlands in 2004. The data were analyzed to determine how many patients were being prescribed antihypertensive medication, how many would have been eligible for HYVET, how many achieved adequate BP control, and whether reaching BP goals was associated with the number and type of antihypertensive medications received or with eligibility for HYVET. RESULTS: During 2004, 518 patients aged > or =80 years visited the geriatric diagnostic day clinic, of whom 147 met the criteria for inclusion in this study. One hundred forty-one patients (95.9%) were receiving antihypertensive medication, although only 52 (35.4%) would have been eligible for HYVET. Dementia, which was an exclusion criterion in HYVET, was the major reason for ineligibility (70 [47.6%]). Greater proportions of patients in this study had comorbidities compared with the HYVET population (stroke: 22.4% vs 6.7%, respectively; myocardial infarction: 7.5% vs 3.1%; heart failure: 11.6% vs 2.9%; diabetes mellitus: 21.1% vs 6.8%). At the time of the clinic visit, 50.3% of patients had adequate BP control, as defined in HYVET (systolic BP <150 mm Hg and diastolic BP <80 mm Hg). Levels of BP control were similar in patients who would and would not have been ineligible for HYVET. Only the mean (SD) number of antihypertensive medications received was significantly associated with the achievement of BP control compared with failure to achieve adequate BP control (2.2 [1.0] vs 1.8 [1.1], respectively; P < 0.05). CONCLUSIONS: Based on the findings of this study, the benefits of treating elderly patients with hypertension in clinical practice may be lower than those reported by HYVET. The study results support the current recommendation that all patients with hypertension should be treated with >1 antihypertensive medication if adequate control is not achieved at low doses of a single medication.

Cardiopulmonary imaging, functional and laboratory studies in sickle cell disease associated pulmonary hypertension.

Pulmonary hypertension (PHT) occurs in approximately 30% of adults with sickle cell disease (SCD) and is an independent risk factor for early death. In this study, we aimed to determine the value of general laboratory testing, plain chest radiography, electrocardiography (ECG), high-resolution computer tomography (HRCT) of the thorax, pulmonary function testing, and plasma N-terminal brain natriuretic peptide (NT-proBNP) and brain natriuretic peptide (BNP) in patients with SCD-related PHT. A cohort of 85 ambulatory sickle cell patients were prospectively screened for PHT with echocardiography (defined as a tricuspid regurgitation flow velocity of > or =2.5 m/sec). All patients were systematically evaluated by the aforementioned diagnostic tests comparing patients with and without PHT. The prevalence of PHT was 41% in HbSS/HbSbeta(0)-thalassemia patients and 13% in HbSC/HbSbeta(+)-thalassemia patients. No statistically significant differences were detected in ECG, chest radiography, HRCT, and pulmonary function testing between patients with and without PHT. The degree of anemia and renal dysfunction, but not the presence of PHT, were the most important determinants of plasma (NT-pro)BNP levels. The performed imaging and functional studies do not seem to be of value in identifying etiological conditions (such as airflow obstruction or parenchymal lung disease) nor do they offer clues to the presence of mild PHT in SCD.

Sickle cell disease-related organ damage occurs irrespective of pain rate: implications for clinical practice.

In daily clinical practice, the frequency of painful crises (pain rate) is an important parameter of sickle cell disease severity. We assessed the prevalence of sickle cell disease-related organ damage and complications and their relation to pain rate. Organ damage and history of vaso-occlusive complications were obtained via systematic screening of consecutive patients and by chart review. In 104 adult sickle cell patients pain rate was related to a history of acute chest syndromes, avascular osteonecrosis, iron overload, priapism and cholelithiasis. However, major disease-related complications, such as microalbuminuria and pulmonary hypertension, were detected in 23% and 24% respectively of patients without painful crises in the study period underlining the importance of systematic screening for developing organ damage in sickle cell patients irrespective of pain rate.

Large and medium-sized pulmonary artery obstruction does not play a role of primary importance in the etiology of sickle-cell disease-associated pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PHT) occurs in approximately 30% of adult patients with sickle-cell disease (SCD) and is a risk factor for early death. The potential role of pulmonary artery obstruction, whether due to emboli or in situ thrombosis, in the etiology of SCD-related PHT is unknown. METHODS: Consecutive SCD patients were screened for PHT (defined as a tricuspid regurgitant jet flow velocity > or = 2.5 m/s) employing echocardiography and were evaluated for pulmonary artery obstruction with ventilation-perfusion (VQ) scintigraphy. RESULTS: Fifty-three HbSS, 6 HbSbeta(0)-thalassemia, 20 HbSC, and 6 HbSbeta(+)-thalassemia patients were included. The overall prevalence of PHT was 41% in HbSS/HbSbeta(0)-thalassemia patients and 13% in HbSC/HbSbeta(+)-thalassemia patients. High-probability VQ defects (Prospective Investigation of Pulmonary Embolism Diagnosis criteria) were detected in two patients, one of whom had PHT. In HbSS/HbSbeta(0)-thalassemia patients with PHT, 19 patients (86%), 2 patients (9%), and 1 patient (5%) had low-, intermediate-, or high-probability scan results as compared to 30 patients (97%), 1 patient (3%), and 0 patients (0%) in HbSS/HbSbeta(0)-thalassemia patients without PHT (p = 0.31). In HbSC/HbSbeta(+)-thalassemia patients with PHT, 3 patients (100%), 0 patients (0%), and 0 patients (0%) had low-, intermediate-, and a high-probability scan as compared to 19 patients (90%), 1 patient (5%), and 1 patient (5%) in HbSC/HbSbeta(+)-thalassemia patients without PHT (p = 0.86). There were no statistical differences in irregular distribution of the radiopharmaceutical or nonspecific signs associated with PHT between patients with and without PHT. CONCLUSIONS: Although small pulmonary artery obstruction cannot be excluded, large to medium-sized pulmonary artery obstruction is an unlikely primary causative factor in SCD-related PHT.

Dengue disease severity in Indonesian children: an evaluation of the World Health Organization classification system.

BACKGROUND: Dengue disease severity is usually classified using criteria set up by the World Health Organization (WHO). We aimed to assess the diagnostic accuracy of the WHO classification system and modifications to this system, and evaluated their potential practical usefulness. METHODS: Patients, admitted consecutively to the hospital with severe dengue, were classified using the WHO classification system and modifications to this system. Treating physicians were asked to classify patients immediately after discharge. We calculated the sensitivity of the various classification systems for the detection of shock and the agreement between the various classification systems and the treating physician's classification. RESULTS: Of 152 patients with confirmed dengue, sixty-six (43%) had evidence of circulatory failure. The WHO classification system had a sensitivity of 86% (95%CI 76-94) for the detection of patients with shock. All modifications to the WHO classification system had a higher sensitivity than the WHO classification system (sensitivity ranging from 88% to 99%). The WHO classification system was in only modest agreement with the intuitive classification by treating physicians whereas several modified classification systems were in good agreement. CONCLUSION: The use of the WHO classification system to classify dengue disease severity is to be questioned, because it is not accurate in correctly classifying dengue disease severity and it lacks sufficient agreement with clinical practice.

ADAMTS13 activity in sickle cell disease.

Sickle red blood cell (SRBC)-endothelial adhesion plays a central role in sickle cell disease (SCD)-related vaso-occlusion. As unusually large von Willebrand factor (ULVWF) multimers mediate SRBC-endothelial adhesion, we investigated the activity of ADAMTS13, the metalloprotease responsible for cleaving ULVWF multimers, in SCD. ADAMTS13 activity was determined using a quantitative immunoblotting assay. VWF:Ag and VWF:RCo were determined using commercial assays. The high-molecular-weight VWF multimer percentage was determined by employing gel electrophoresis. ADAMTS13 activity was similar among asymptomatic patients (n = 8), patients at presentation with a painful crisis (n = 23), and healthy controls. ADAMTS13/VWF:Ag ratios were lower in patients compared to healthy HbAA controls, with the lowest values at presentation with a painful crisis (P = 0.02). Division of samples in those with VWF:RCo/VWF:Ag ratios < 0.70 and those with ratios >or= 0.70 revealed significantly more samples with ratios >or= 0.70 (P = 0.01) collected during painful crises. ULVWF multimers were detected in 6 patient samples and in 1 control sample. ADAMTS13/VWF:Ag ratios were inversely related to the duration of symptoms at presentation with an acute vaso-occlusive event (r(s)-0.67, P = 0.002). Although SCD is characterized by elevated VWF:Ag levels, no severe ADAMTS13 deficiency was detected in our patients.

Prognostic value of echocardiographically assessed right ventricular dysfunction in patients with pulmonary embolism.

BACKGROUND: Echocardiographically assessed right ventricular dysfunction is increasingly used to guide more aggressive therapy in hemodynamically stable patients with acute pulmonary embolism (PE). However, the prognostic value of right ventricular dysfunction in these patients is still unclear. METHODS: We systemically reviewed the literature to assess the prevalence of echocardiographic right ventricular dysfunction and the association with adverse outcomes in patients with PE who had this condition. The methodologic quality of each study was scored. Absolute risks of the outcome events were calculated for each study separately, and positive predictive values of PE-related mortality were determined for normotensive patients. RESULTS: Seven studies were included. All had methodologic shortcomings, but they suggested an at least 2-fold increased risk of PE-related mortality in patients with right ventricular dysfunction, the prevalence of which varied from 40% to 70%. However, this seems to be less convincing in hemodynamically stable patients. The only 2 studies that allowed for an estimation of the accuracy in normotensive patients showed low positive predictive values of echocardiographic right ventricular dysfunction for PE-related in-hospital mortality (positive predictive value, 4% and 5% in the 2 studies). CONCLUSION: It remains unclear whether echocardiographic right ventricular dysfunction is a prevalent and reliable predictor of adverse outcomes in hemodynamically stable patients with acute PE.

Oral contraceptives and inherited thrombophilia: a gene-environment interaction with a risk of venous thrombosis?

There are indications in the literature that asymptomatic women with an inherited thrombophilic defect who use oral contraceptive have an increased risk of venous thrombosis. There are no consistent data regarding the thrombotic risk in users of oral contraceptives with an inherited thrombophilic defect and personal history of venous thrombosis. Selective genetic screening on the basis of clinical judgment, and family and personal history, instead of universal screening, may be useful before oral contraceptives are prescribed. Nonetheless, the actual risks and benefits of such practice remain to be examined.

Travel and the risk of symptomatic venous thromboembolism.

Whether long-distance travel and symptomatic venous thromboembolism (VTE) are associated is debated. On the basis of the available literature a fair risk estimate cannot be obtained. We estimated an accurate odds ratio for the relationship between recent travelling and symptomatic VTE. From three case-control studies consisting of 788 and 170 patients with clinically suspected deep vein thrombosis (DVT) and 989 patients with clinically suspected pulmonary embolism (PE) referred for diagnostic work-up, a pooled odds ratio for the relation between travel and symptomatic VTE was calculated. Cases were patients in whom the diagnosis was confirmed according to a diagnostic management strategy, whereas controls were patients in whom the diagnosis was excluded and who had an uneventful clinical follow-up. Patients were seen in the period April 1997 to September 2000. Travel history was recorded prior to diagnostic work-up. The pooled odds ratio for the association between any travel and symptomatic venous thromboembolism was 0.9 (95% CI: 0.6-1.4). The median travel time was 7 h (quartile range 4 to 10 h). Separate analyses performed for different types of transport (plane, car, bus or train) yielded comparable odds ratios. The analysis for duration of travelling showed an increased odds ratio of 2.5 (95% CI: 1.0-6.2) in the category of 10-15 h of travelling. This study shows that the average traveller does not have an increased risk for symptomatic venous thromboembolism. Only very long travelling (more than 10 h) may be associated with venous thromboembolic disease.

Embolus location affects the sensitivity of a rapid quantitative D-dimer assay in the diagnosis of pulmonary embolism.

D-dimer blood tests have been suggested to rule out pulmonary embolism. Despite evidence of the safety of withholding anticoagulant treatment in patients with suspected pulmonary embolism and a normal D-dimer assay result, clinicians remain reluctant to use a D-dimer assay as a sole diagnostic test. This prospective study in 314 consecutive inpatients and outpatients investigates the relation between the diagnostic accuracy of D-dimer plasma concentration and pulmonary embolus location. Plasma D-dimer levels were measured using a quantitative immunoturbidimetric method. A strict protocol of ventilation-perfusion scintigraphy, pulmonary angiography, and spiral computed tomography was used to arrive at a final diagnosis and to assess the largest pulmonary artery in which embolus was visible. The influence of embolus location on the diagnostic accuracy was evaluated using the Kruskal-Wallis test and receiver operator characteristics (ROC) analysis. There was a strong correlation between plasma D-dimer concentration and embolus location (Kruskal-Wallis, p < 0.001). Thus, the assay showed greater accuracy in excluding segmental or larger emboli (sensitivity = 93%) than subsegmental emboli (sensitivity = 50%). D-dimer concentration and the accuracy of D-dimer assays are clearly dependent on embolus location and smaller, subsegmental emboli may be missed when D-dimer assays are used as a sole test to exclude pulmonary embolism.