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Articles by D. J Cohen
Total Records ( 7 ) for D. J Cohen
  J. M Stolker , K. F Kennedy , J. B Lindsey , S. P Marso , M. J Pencina , D. E Cutlip , L Mauri , N. S Kleiman , D. J Cohen and on behalf of the EVENT Investigators

Prediction of restenosis after percutaneous coronary intervention (PCI) remains challenging, and existing risk assessment algorithms were developed before the widespread adoption of drug-eluting stents (DES).

Methods and Results—

We used data from the EVENT registry to develop a risk model for predicting target lesion revascularization (TLR) in 8829 unselected patients undergoing DES implantation between 2004 and 2007. Using a split-sample validation technique, predictors of TLR at 1 year were identified from two thirds of the subjects (derivation cohort) using multiple logistic regression. Integer point values were created for each predictor, and the summed risk score (range, 0 to 10) was applied to the remaining sample (validation cohort). At 1 year, TLR occurred in 4.2% of patients, and after excluding stent thrombosis and early mechanical complications, the incidence of late TLR (more likely representing restenosis-related TLR) was 3.6%. Predictors of TLR were age <60, prior PCI, unprotected left main PCI, saphenous vein graft PCI, minimum stent diameter ≤2.5 mm, and total stent length ≥40 mm. Comparison of observed versus predicted rates of TLR according to risk score demonstrated good model fit in the validation set. There was more than a 3-fold difference in TLR rates between the lowest risk category (score=0; TLR rate, 2.2%) and the highest risk category (score ≥5; TLR rate, 7.5%).


The overall incidence of TLR remains low among unselected patients receiving DES in routine clinical practice. A simple risk model incorporating 6 readily available clinical and angiographic variables helps identify individuals at extremely low (<2%) and modestly increased (>7%) risk of TLR after DES implantation.

  S. V Arnold , D. A Morrow , Y Lei , D. J Cohen , E. M Mahoney , E Braunwald and P. S. Chan

Background— Angina in patients with coronary artery disease is associated with worse quality of life; however, the relationship between angina frequency and resource utilization is unknown.

Methods and Results— Using data from the MERLIN-TIMI 36 trial, we assessed the association between the extent of angina after an acute coronary syndrome (ACS) and subsequent cardiovascular resource utilization among 5460 stable outpatients who completed the Seattle Angina Questionnaire at 4 months after an ACS and who were then followed for an additional 8 months. Angina frequency was categorized as none (score, 100; 2739 patients), monthly (score, 61 to 99; 1608 patients), weekly (score, 31 to 60; 854 patients), and daily (score, 0 to 30; 259 patients). Multivariable regression models evaluated the association between angina frequency and overall costs attributable to cardiovascular hospitalizations, outpatient visits and procedures, and medications. As compared with no angina, overall costs increased in a graded fashion with higher angina frequency—no angina, $2928 (reference); monthly angina, $3909 (adjusted relative cost ratio, 1.29; 95% CI, 1.21 to 1.39); weekly angina, $4558 (adjusted relative cost ratio, 1.52; 95% CI, 1.48 to 1.67); and daily angina, $6949 (adjusted relative cost ratio, 2.32; 95% CI, 2.01 to 2.69; P for trend <0.001). Differences in costs were attributable primarily to higher rates of ACS hospitalization and coronary revascularization among patients with more severe angina.

Conclusion— Among stable outpatients after ACS, a direct graded relationship was found between higher angina frequency and healthcare costs. As compared with patients without angina, patients with daily angina had a >2-fold increase in resource utilization and incremental costs of $4000 after 8 months of follow-up.

  E. D Peterson , J. A Spertus , D. J Cohen , M. A Hlatky , A. S Go , B. G Vickrey , J. L Saver and P. C. Hinton

Background— The field of outcomes research seeks to define optimal treatment in practice and to promote the rapid full adoption of efficacious therapies into routine clinical care. The American Heart Association (AHA) formed the AHA Pharmaceutical Roundtable (PRT) Outcomes Research Centers Network to accelerate attainment of these goals. Participating centers were intended to carry out state-of-the-art outcomes research in cardiovascular disease and stroke, to train the next generation of investigators, and to support the formation of a collaborative research network.

Program— After a competitive application process, 4 AHA PRT Outcomes Research Centers were selected: Duke Clinical Research Institute; Saint Luke’s Mid America Heart Institute; Stanford University–Kaiser Permanente of Northern California; and University of California, Los Angeles. Each center proposed between 1 and 3 projects organized around a single theme in cardiovascular disease or stroke. Additionally, each center will select and train up to 6 postdoctoral fellows over the next 4 years, and will participate in cross-collaborative activities among the centers.

Conclusions— The AHA PRT Outcomes Research Centers Network is designed to further strengthen the field of cardiovascular disease and stroke outcomes research by fostering innovative research, supporting high quality training, and encouraging center-to-center collaborations.

  A. P Amin , S. P Marso , S. V Rao , J Messenger , P. S Chan , J House , K Kennedy , K Robertus , D. J Cohen and E. M. Mahoney

Although bivalirudin compared with unfractionated heparin with glycoprotein IIb/IIIa inhibitors reduces bleeding and hospitalization costs in patients undergoing percutaneous coronary intervention (PCI), little is known about the economic impact of bivalirudin versus heparin alone and at what threshold of procedural bleeding risk bivalirudin would be considered cost-effective.

Methods and Results—

A validated model was used to predict risk of major bleeding for 81 628 National Cardiovascular Data Registry (NCDR) CathPCI Registry patients from 2004 to 2006 who received unfractionated heparin only. Costs were derived from multiple sources including wholesale acquisition costs (for drugs) and single-center data (for PCI-related complications). Based on ISAR-REACT 3, we assumed that bivalirudin would reduce the risk of major bleeding by 33% compared with unfractionated heparin alone. A Markov model was used to estimate lost life expectancy associated with a major bleed. Major bleeding was predicted to occur in 2.2% of patients. Bivalirudin for all patients was estimated to increase costs by $571 per patient, yielding cost-effectiveness ratios of $287 473 per bleeding event averted and $1 173 360 per quality-adjusted life-year gained. Bivalirudin was cost saving for patients with a predicted bleeding risk >20% (0.16% of CathPCI population). At willingness-to-pay thresholds of $50K and $100K per quality-adjusted life-year gained, bivalirudin was cost-effective for patients with a bleeding risk ≥8% (2.5% patients) and ≥5% (7.9% patients), respectively.


This decision-analytic modeling study demonstrates that for patients undergoing PCI, substitution of bivalirudin for unfractionated heparin monotherapy is projected to increase costs for virtually all patients and would be considered cost-effective for only a minority of patients with a high bleeding risk. From a policy standpoint, studies such as this, aimed at identifying the appropriate risk threshold for initiating treatment, may help in the development of informed guidelines for the use of expensive therapies.

  M. R Reynolds , J Walczak , S. A White , D. J Cohen and D. J. Wilber

In patients with paroxysmal atrial fibrillation (AF), catheter ablation maintains sinus rhythm more effectively than antiarrhythmic drugs (AADs), but its effect on symptoms and quality of life (QOL) has not been fully characterized.

Methods and Results—

We evaluated symptoms and QOL in a multicenter, randomized trial comparing catheter ablation with AADs as second-line treatment for patients with paroxysmal AF. The Short Form (SF)-36 health survey and the AF Symptom Checklist were administered at baseline and 3, 6, and 9 months after a blanking or dose-titration period. The primary between-group comparisons were conducted at 3 months because of permitted crossover from AAD to ablation beyond this time. Additional analyses based on subsequent follow-up were performed, including the construction of mixed linear regression models to assess the impact of multiple factors on follow-up QOL scores.

At baseline in both the ablation (n=103) and the AAD (n=56) groups, 7 of 8 SF-36 scales were well below population norms, as were the physical (PCS) and mental (MCS) summary scores. At 3 months, the same 7 SF-36 scales were significantly (P<0.01) higher in the ablation than in the AAD group, as were the PCS (52.0±7.8 versus 47.1±10.6; P<0.01) and MCS (52.4±8.1 versus 46.6±9.8; P<0.01) scores, whereas symptom frequency (9.3±9.2 versus 19.0±12.6; P<0.001) and symptom severity (7.7±7.2 versus 16.2±10.0; P<0.001) were significantly reduced. In multivariable analysis, ablation and recurrent arrhythmias most strongly correlated with QOL changes over time.


For second-line therapy of paroxysmal AF, ablation is superior to AAD treatment at improving symptoms and QOL.

Clinical Trial Registration—

URL: Unique identifier: NCT00116428.

  E. M Mahoney , K Wang , H. H Keo , S Duval , K. G Smolderen , D. J Cohen , G Steg , D. L Bhatt , A. T Hirsch and on behalf of the Reduction of Atherothrombosis for Continued Health (REACH) Registry Investigators

Peripheral artery disease (PAD) is common and imposes a high risk of major systemic and limb ischemic events. The REduction of Atherothrombosis for Continued Health (REACH) Registry is an international prospective registry of patients at risk of atherothrombosis caused by established arterial disease or the presence of ≥3 atherothrombotic risk factors.

Methods and Results—

We compared the 2-year rates of vascular-related hospitalizations and associated costs in US patients with established PAD across patient subgroups. Symptomatic PAD at enrollment was identified on the basis of current intermittent claudication with an ankle-brachial index (ABI) <0.90 or a history of lower-limb revascularization or amputation. Asymptomatic PAD was diagnosed on the basis of an enrollment ABI <0.90 in the absence of symptoms. Overall, 25 763 of the total 68 236–patient REACH cohort were enrolled from US sites; 2396 (9.3%) had symptomatic and 213 (0.8%) had asymptomatic PAD at baseline. One- and cumulative 2-year follow-up data were available for 2137 (82%) and 1677 (64%) of US REACH patients with either symptomatic or asymptomatic PAD, respectively. At 2 years, mean cumulative hospitalization costs, per patient, were $7445, $7000, $10 430, and $11 693 for patients with asymptomatic PAD, a history of claudication, lower-limb amputation, and revascularization, respectively (P=0.007). A history of peripheral intervention (lower-limb revascularization or amputation) was associated with higher rates of subsequent procedures at both 1 and 2 years.


The economic burden of PAD is high. Recurring hospitalizations and repeat revascularization procedures suggest that neither patients, physicians, nor healthcare systems should assume that a first admission for a lower-extremity PAD procedure serves as a permanent resolution of this costly and debilitating condition.

  R. W Evans , W. H Applegate , D. M Briscoe , D. J Cohen , C. C Rorick , B. T Murphy and J. C. Madsen

Background and objectives: Immunosuppressive medications are essential in preventing kidney transplant rejection. Continuous insurance coverage for outpatient immunosuppressive medications remains a major issue. The objective of this study was to establish the prevalence and consequences of cost-related immunosuppressive medication nonadherence.

Design, setting, participants, & measurements: A descriptive survey of all U.S. kidney transplant programs (n = 254) was conducted. The response rate for the survey exceeded 99%. The main outcome measures included the following: transplant recipient concerns related to medication costs, ability to pay for medications, medication nonadherence and its consequences, and failure of transplant centers to place patients on the transplant waiting list.

Results: Continuous insurance coverage for outpatient immunosuppressive drugs is a problem having potentially grave consequences for the majority of kidney transplant recipients. More than 70% of kidney transplant programs report that their patients have an extremely or very serious problem paying for their medications. About 47% of the programs indicate that more than 40% of their patients are having difficulty paying for their immunosuppressive medications. In turn, 68% of the programs report deaths and graft losses attributable to cost-related immunosuppressive medication nonadherence. Some of the problems identified here are more significant for adult than pediatric patients.

Conclusions: The prevalence and consequences of cost-related immunosuppressive medication nonadherence among kidney transplant recipients have now been documented. The results presented here should serve as the necessary impetus for the development of health care policies supporting Medicare coverage of immunosuppressive medications for the life of the transplanted kidney.

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