Programs from the Centers for Medicare and Medicaid Services simultaneously promote strategies to lower hospital admissions and readmissions. However, there is concern that hospitals in communities that successfully reduce admissions may be penalized, as patients that are ultimately hospitalized may be sicker and at higher risk of readmission. We therefore examined the relationship between changes from 2010 to 2013 in admission rates and thirty-day readmission rates for elderly Medicare beneficiaries. We found that communities with the greatest decline in admission rates also had the greatest decline in thirty-day readmission rates, even though hospitalized patients did grow sicker as admission rates declined. The relationship between changing admission and readmission rates persisted in models that measured observed readmission rates, risk-standardized readmission rates, and the combined rate of readmission and death. Our findings suggest that communities can reduce admission rates and readmission rates in parallel, and that federal policy incentivizing reductions in both outcomes does not create contradictory incentives.
IMPORTANCE: Dual antiplatelet therapy after percutaneous coronary intervention (PCI) reduces ischemia but increases bleeding.
OBJECTIVE: To develop a clinical decision tool to identify patients expected to derive benefit vs harm from continuing thienopyridine beyond 1 year after PCI.
DESIGN, SETTING, AND PARTICIPANTS: Among 11,648 randomized DAPT Study patients from 11 countries (August 2009-May 2014), a prediction rule was derived stratifying patients into groups to distinguish ischemic and bleeding risk 12 to 30 months after PCI. Validation was internal via bootstrap resampling and external among 8136 patients from 36 countries randomized in the PROTECT trial (June 2007-July 2014).
EXPOSURES: Twelve months of open-label thienopyridine plus aspirin, then randomized to 18 months of continued thienopyridine plus aspirin vs placebo plus aspirin.
MAIN OUTCOMES AND MEASURES: Ischemia (myocardial infarction or stent thrombosis) and bleeding (moderate or severe) 12 to 30 months after PCI.
RESULTS: Among DAPT Study patients (derivation cohort; mean age, 61.3 years; women, 25.1%), ischemia occurred in 348 patients (3.0%) and bleeding in 215 (1.8%). Derivation cohort models predicting ischemia and bleeding had c statistics of 0.70 and 0.68, respectively. The prediction rule assigned 1 point each for myocardial infarction at presentation, prior myocardial infarction or PCI, diabetes, stent diameter less than 3 mm, smoking, and paclitaxel-eluting stent; 2 points each for history of congestive heart failure/low ejection fraction and vein graft intervention; -1 point for age 65 to younger than 75 years; and -2 points for age 75 years or older. Among the high score group (score ≥2, n = 5917), continued thienopyridine vs placebo was associated with reduced ischemic events (2.7% vs 5.7%; risk difference [RD], -3.0% [95% CI, -4.1% to -2.0%], P < .001) compared with the low score group (score <2, n = 5731; 1.7% vs 2.3%; RD, -0.7% [95% CI, -1.4% to 0.09%], P = .07; interaction P < .001). Conversely, continued thienopyridine was associated with smaller increases in bleeding among the high score group (1.8% vs 1.4%; RD, 0.4% [95% CI, -0.3% to 1.0%], P = .26) compared with the low score group (3.0% vs 1.4%; RD, 1.5% [95% CI, 0.8% to 2.3%], P < .001; interaction P = .02). Among PROTECT patients (validation cohort; mean age, 62 years; women, 23.7%), ischemia occurred in 79 patients (1.0%) and bleeding in 37 (0.5%), with a c statistic of 0.64 for ischemia and 0.64 for bleeding. In this cohort, the high-score patients (n = 2848) had increased ischemic events compared with the low-score patients and no significant difference in bleeding.
CONCLUSION AND RELEVANCE: Among patients not sustaining major bleeding or ischemic events 1 year after PCI, a prediction rule assessing late ischemic and bleeding risks to inform dual antiplatelet therapy duration showed modest accuracy in derivation and validation cohorts. This rule requires further prospective evaluation to assess potential effects on patient care, as well as validation in other cohorts.
TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00977938.
BACKGROUND: Cardiac implantable electric devices are commonly used to treat heart failure. Little is known about temporal and geographic variation in use of cardiac resynchronization therapy (CRT) devices in usual care settings.
METHODS AND RESULTS: We identified new CRT with pacemaker (CRT-P) or defibrillator generators (CRT-D) implanted between 2008 and 2013 in the United States from a commercial claims database. For each implant, we characterized prior medication use, comorbidities, and geography. Among 17 780 patients with CRT devices (median age 69, 31% women), CRT-Ps were a small and increasing share of CRT devices, growing from 12% to 20% in this study period. Compared to CRT-D recipients, CRT-P recipients were older (median age 76 versus 67), and more likely to be female (40% versus 30%). Pre-implant use of β-blockers and angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers was low in both CRT-D (46%) and CRT-P (31%) patients. The fraction of CRT-P devices among all new implants varied widely across states. Compared to the increasing national trend, the share of CRT-P implants was relatively increasing in Kansas and relatively decreasing in Minnesota and Oregon.
CONCLUSIONS: In this large, contemporary heart failure population, CRT-D use dwarfed CRT-P, though the latter nearly doubled over 6 years. Practice patterns vary substantially across states and over time. Medical therapy appears suboptimal in real-world practice.
BACKGROUND: Older recipients of implantable cardioverter-defibrillators (ICDs) are at increased risk for short-term mortality in comparison with younger patients. Although hospice use is common among decedents aged >65, its use among older ICD recipients is unknown.
METHODS AND RESULTS: Medicare patients aged >65 matched to data in the National Cardiovascular Data Registry - ICD Registry from January 1, 2006 to March 31, 2010 were eligible for analysis (N=194 969). The proportion of ICD recipients enrolled in hospice, cumulative incidence of hospice admission, and factors associated with time to hospice enrollment were evaluated. Five years after device implantation, 50.9% of patients were either deceased or in hospice. Among decedents, 36.8% received hospice services. The cumulative incidence of hospice enrollment, accounting for the competing risk of death, was 4.7% (95% confidence interval [CI], 4.6%-4.8%) within 1 year and 21.3% (95% CI, 20.7%-21.8%) at 5 years. Factors most strongly associated with shorter time to hospice enrollment were older age (adjusted hazard ratio, 1.77; 95% CI, 1.73-1.81), class IV heart failure (versus class I; adjusted hazard ratio, 1.79; 95% CI, 1.66-1.94); ejection fraction <20 (adjusted hazard ratio, 1.57; 95% CI, 1.48-1.67), and greater hospice use among decedents in the patients' health referral region.
CONCLUSIONS: More than one-third of older patients dying with ICDs receive hospice care. Five years after implantation, half of older ICD recipients are either dead or in hospice. Hospice providers should be prepared for ICD patients, whose clinical trajectories and broader palliative care needs require greater focus.
OBJECTIVES: To characterize hospital phenotypes by their combined utilization pattern of percutaneous coronary interventions (PCI), coronary artery bypass grafting (CABG) procedures, and intensive care unit (ICU) admissions for patients hospitalized for acute myocardial infarction (AMI).
RESEARCH DESIGN: Using the Premier Analytical Database, we identified 129,138 hospitalizations for AMI from 246 hospitals with the capacity for performing open-heart surgery during 2010-2013. We calculated year-specific, risk-standardized estimates of PCI procedure rates, CABG procedure rates, and ICU admission rates for each hospital, adjusting for patient clinical characteristics and within-hospital correlation of patients. We used a mixture modeling approach to identify groups of hospitals (ie, hospital phenotypes) that exhibit distinct longitudinal patterns of risk-standardized PCI, CABG, and ICU admission rates.
RESULTS: We identified 3 distinct phenotypes among the 246 hospitals: (1) high PCI-low CABG-high ICU admission (39.2% of the hospitals), (2) high PCI-low CABG-low ICU admission (30.5%), and (3) low PCI-high CABG-moderate ICU admission (30.4%). Hospitals in the high PCI-low CABG-high ICU admission phenotype had significantly higher risk-standardized in-hospital costs and 30-day risk-standardized payment yet similar risk-standardized mortality and readmission rates compared with hospitals in the low PCI-high CABG-moderate ICU admission phenotype. Hospitals in these phenotypes differed by geographic region.
CONCLUSIONS: Hospitals differ in how they manage patients hospitalized for AMI. Their distinctive practice patterns suggest that some hospital phenotypes may be more successful in producing good outcomes at lower cost.
Background Thirty-day risk-standardized mortality rates after acute myocardial infarction are commonly used to evaluate and compare hospital performance. However, it is not known whether differences among hospitals in the early survival of patients with acute myocardial infarction are associated with differences in long-term survival. Methods We analyzed data from the Cooperative Cardiovascular Project, a study of Medicare beneficiaries who were hospitalized for acute myocardial infarction between 1994 and 1996 and who had 17 years of follow-up. We grouped hospitals into five strata that were based on case-mix severity. Within each case-mix stratum, we compared life expectancy among patients admitted to high-performing hospitals with life expectancy among patients admitted to low-performing hospitals. Hospital performance was defined by quintiles of 30-day risk-standardized mortality rates. Cox proportional-hazards models were used to calculate life expectancy. Results The study sample included 119,735 patients with acute myocardial infarction who were admitted to 1824 hospitals. Within each case-mix stratum, survival curves of the patients admitted to hospitals in each risk-standardized mortality rate quintile separated within the first 30 days and then remained parallel over 17 years of follow-up. Estimated life expectancy declined as hospital risk-standardized mortality rate quintile increased. On average, patients treated at high-performing hospitals lived between 0.74 and 1.14 years longer, depending on hospital case mix, than patients treated at low-performing hospitals. When 30-day survivors were examined separately, there was no significant difference in unadjusted or adjusted life expectancy across hospital risk-standardized mortality rate quintiles. Conclusions In this study, patients admitted to high-performing hospitals after acute myocardial infarction had longer life expectancies than patients treated in low-performing hospitals. This survival benefit occurred in the first 30 days and persisted over the long term. (Funded by the National Heart, Lung, and Blood Institute and the National Institute of General Medical Sciences Medical Scientist Training Program.).
Public reporting of health care data continues to proliferate as consumers and other stakeholders seek information on the quality and outcomes of care. Medicare's Hospital Compare website, the U.S. News & World Report hospital rankings, and several state-level programs are well known. Many rely heavily on administrative data as a surrogate to reflect clinical reality. Clinical data are traditionally more difficult and costly to collect, but more accurately reflect patients' clinical status, thus enhancing the validity of quality metrics. We describe the public reporting effort being launched by the American College of Cardiology and partnering professional organizations using clinical data from the National Cardiovascular Data Registry (NCDR) programs. This hospital-level voluntary effort will initially report process of care measures from the percutaneous coronary intervention (CathPCI) and implantable cardioverter-defibrillator (ICD) registries of the NCDR. Over time, additional process, outcomes, and composite performance metrics will be reported.
OBJECTIVE: Antipsychotic use among young children has grown rapidly despite a lack of approval by the U.S. Food and Drug Administration (FDA) for broad use in this age group. Characteristics of physicians who prescribed antipsychotics to young children were identified, and prescribing patterns involving young children and adults were compared.
METHODS: Physician-level prescribing data from IMS Health's Xponent database were linked with American Medical Association Masterfile data and analyzed. The sample included all U.S. psychiatrists and a random sample of 5% of family medicine physicians who wrote at least ten antipsychotic prescriptions per year from 2008 to 2011 (N=31,713). Logistic and hierarchical binomial regression models were estimated to examine physician prescribing for children ages zero to nine, and the types and numbers of ingredients used for children versus adults ages 20 to 64 were compared.
RESULTS: Among antipsychotic prescribers, 42.2% had written at least one antipsychotic prescription for young children. Such prescribing was more likely among physicians age ≤39 versus ≥60 (odds ratio [OR]=1.70) and physicians in rural versus nonrural areas (OR=1.11) and was less likely among males (OR=.93) and graduates of a top-25 versus a lower-ranked U.S. medical school (OR=.87). Among physicians who prescribed antipsychotics to young children and adults, 75.0% of prescriptions for children and 35.7% of those for adults were for drugs with an FDA-approved indication for that age. Fewer antipsychotic agents were prescribed for young children (median=2) versus adults (median=7).
CONCLUSIONS: Prescribing antipsychotics for young children was relatively common, but prescribing patterns differed between young children and adults.
BACKGROUND AND OBJECTIVE: Women of color (WOC) (African American, Hispanic, Native American/Alaskan Native, and Asian American) faculty remain disproportionately underrepresented among medical school faculty and especially at senior ranks compared with White female faculty. The barriers or facilitators to the career advancement of WOC are poorly understood. The Women and Inclusion in Academic Medicine (WIAM) study was developed to characterize individual, institutional and sociocultural factors that influence the entry, progression and persistence, and advancement of women faculty in academic medical careers with a focus on WOC.
METHODS: Using a purposive sample of 13 academic medical institutions, we collected qualitative interview data from 21 WOC junior faculty and quantitative data from 3,127 (38.9% of 8,053 eligible women) respondents via an online survey. To gather institutional data, we used an online survey and conducted 23 key administrative informant interviews from the 13 institutions. Grounded theory methodology will be used to analyze qualitative data. Multivariable analysis including hierarchical linear modeling will be used to investigate outcomes, such as the inclusiveness of organizational gender climate and women faculty's intent to stay.
CONCLUSION: We describe the design, methods, rationale and limitations of one of the largest and most comprehensive studies of women faculty in academic medicine with a focus on WOC. This study will enhance our understanding of challenges that face women, and, especially WOC, faculty in academic medicine and will provide solutions at both the individual and institutional levels.
BACKGROUND: Regional variation in US Medicare prescription drug spending is driven by higher prescribing of costly brand-name drugs in some regions. This variation likely arises from differences in the speed of diffusion of newly-approved medications. Second-generation antipsychotics were widely adopted for treatment of severe mental illness and for several off-label uses. Rapid diffusion of new psychiatric drugs likely increases drug spending but its relationship to non-drug spending is unclear. The impact of antipsychotic diffusion on drug and medical spending is of great interest to public payers like Medicare, which finance a majority of mental health spending in the US.
AIMS: We examine the association between physician adoption of new antipsychotics and antipsychotic spending and non-drug medical spending among disabled and elderly Medicare enrollees.
METHODS: We linked physician-level data on antipsychotic prescribing from an all-payer dataset (IMS Health's XponentTM) to patient-level data from Medicare. Our physician sample included 16,932 US. psychiatrists and primary care providers with > 10 antipsychotic prescriptions per year from 1997-2011. We constructed a measure of physician adoption of 3 antipsychotics introduced during this period (quetiapine, ziprasidone and aripiprazole) by estimating a shared frailty model of the time to first prescription for each drug. We then assigned physicians to one of 306 U.S. hospital referral regions (HRRs) and measured the average propensity to adopt per region. Using 2010 data for a random sample of 1.6 million Medicare beneficiaries, we identified 138,680 antipsychotic users. A generalized linear model with gamma distribution and log link was used to estimate the effect of region-level adoption propensity on beneficiary-level antipsychotic spending and non-drug medical spending adjusting for patient demographic and socioeconomic characteristics, health status, eligibility category, and whether the antipsychotic was for an on- vs. off-label use.
RESULTS: In our sample, mean patient age was 62 years, 42% were male, and 86% had low-income. Half of antipsychotic users in Medicare had an on-label indication. The weighted average propensity to adopt the three new antipsychotics varied four-fold across HRRs. For every one standard deviation increase in the propensity to adopt there was a 5% increase in antipsychotic spending after adjusting for covariates (adjusted ratio of spending 1.05, 95% CI 1.01-1.08, p = 0.005). Physician propensity to adopt new antipsychotics was not associated with non-drug medical spending (adjusted ratio 0.96, 95% CI 0.91-1.01, p < 0.117).
DISCUSSION: These findings suggest wide regional variation in physicians' propensity to adopt new antipsychotic medications. While physician adoption of new antipsychotics was positively associated with antipsychotic expenditures, it was not associated with non-drug spending. Our analysis is limited to Medicare and may not generalize to other payers. Also, claims data do not allow for the measurement of health outcomes, which would be important to evaluate when calculating the value of rapid vs. slow technology adoption.
BACKGROUND: Academic medical centers (AMCs) have increasingly adopted conflict of interest policies governing physician-industry relationships; it is unclear how policies impact prescribing.
OBJECTIVES: To determine whether 9 American Association of Medical Colleges (AAMC)-recommended policies influence psychiatrists' antipsychotic prescribing and compare prescribing between academic and nonacademic psychiatrists.
RESEARCH DESIGN: We measured number of prescriptions for 10 heavily promoted and 9 newly introduced/reformulated antipsychotics between 2008 and 2011 among 2464 academic psychiatrists at 101 AMCs and 11,201 nonacademic psychiatrists. We measured AMC compliance with 9 AAMC recommendations. Difference-in-difference analyses compared changes in antipsychotic prescribing between 2008 and 2011 among psychiatrists in AMCs compliant with ≥ 7/9 recommendations, those whose institutions had lesser compliance, and nonacademic psychiatrists.
RESULTS: Ten centers were AAMC compliant in 2008, 30 attained compliance by 2011, and 61 were never compliant. Share of prescriptions for heavily promoted antipsychotics was stable and comparable between academic and nonacademic psychiatrists (63.0%-65.8% in 2008 and 62.7%-64.4% in 2011). Psychiatrists in AAMC-compliant centers were slightly less likely to prescribe these antipsychotics compared with those in never-compliant centers (relative odds ratio, 0.95; 95% CI, 0.94-0.97; P < 0.0001). Share of prescriptions for new/reformulated antipsychotics grew from 5.3% in 2008 to 11.1% in 2011. Psychiatrists in AAMC-compliant centers actually increased prescribing of new/reformulated antipsychotics relative to those in never-compliant centers (relative odds ratio, 1.39; 95% CI, 1.35-1.44; P < 0.0001), a relative increase of 1.1% in probability.
CONCLUSIONS: Psychiatrists exposed to strict conflict of interest policies prescribed heavily promoted antipsychotics at rates similar to academic psychiatrists and nonacademic psychiatrists exposed to less strict or no policies.
BACKGROUND: Current approaches for postmarket medical device safety surveillance are limited in their ability to produce timely and accurate assessments of adverse event rates.
METHODS AND RESULTS: The Data Extraction and Longitudinal Trend Analysis (DELTA) network study was a multicenter prospective observational study designed to evaluate the safety of devices used during percutaneous coronary interventions. All adult patients undergoing percutaneous coronary intervention from January 2008 to December 2012 at 5 participating Massachusetts sites were included. A safety alert was triggered if the cumulative observed adverse event rates for the study device exceeded the upper 95% confidence interval of the event rates of propensity-matched control cohort. Prespecified sensitivity analyses were developed to validate any identified safety signal. A total of 23,805 consecutive percutaneous coronary intervention procedures were evaluated. Two of 24 safety analyses triggered safety alerts. Patients receiving Perclose vascular closure device experienced an increased risk of minor vascular complications (relative risk, 4.14; P<0.01) and any vascular complication (relative risk, 2.06; P=0.01) when compared with propensity-matched patients receiving alternative vascular closure device, a result primarily driven by relatively high event rates at 1 participating center. Sensitivity analyses based on alternative risk adjustment methods confirmed a pattern of increased rate of complications at 1 of the 5 participating sites in their use of Perclose vascular closure device.
CONCLUSIONS: The DELTA network study demonstrates that distributed automated prospective safety surveillance has the potential of providing near real-time assessment of safety risks of newly approved medical devices.
BACKGROUND: The safety of drug-eluting stents (DES) vs. bare metal stents (BMS) in the perioperative setting, a heightened state of inflammation and thrombosis is not well defined.
METHODS: All adults undergoing noncardiac surgical (NCS) procedures within 1 year following percutaneous coronary intervention (PCI) in Massachusetts between April 1, 2004, and September 30, 2007, were identified from an administrative claims database. Patients were divided into those who received BMS vs. DES at index PCI. Primary net clinical outcome was death, myocardial infarction (MI) or bleeding within 30 days of NCS. Primary clinical outcome was 30-day death or MI.
RESULTS: Among 8,415 (22% BMS) patients that satisfied our inclusion criteria, 1,838 BMS patients were matched with 3,565 DES patients with similar propensity scores. In the DES cohort, the 30-day primary net clinical outcome rate was lower with longer time from PCI to NCS (P = 0.02) with lowest rates if NCS was performed after 90 days from PCI (event rate 8.57, 7.53, 5.21, and 5.75% for 1-30, 31-90, 91-180, and 181-365 days from PCI to NCS). However, in the BMS cohort, the event rate was uniformly high regardless of the time from PCI to NCS (P = 0.60) (event rate 8.20, 6.56, 8.05, and 8.82% for 1-30, 31-90, 91-180, and 181-365 days from PCI to NCS). There was no significant difference between DES and the BMS group for 30-day primary net clinical outcome (6.64 vs. 7.89%; P = 0.10), but there was a 26% lower odds of primary clinical outcome (OR = 0.74, 95% CI 0.58-0.94) with DES when compared with BMS, driven mainly by differences in event rates when NCS was performed >90 days post PCI.
CONCLUSION: DES implantation was not associated with higher adverse events after NCS. Moreover, the incidence of adverse events following NCS was lower when NCS was performed >90 days post-DES implantation suggesting that it may not be necessary to wait until 12 months post PCI with DES before NCS.
BACKGROUND: Early readmission after percutaneous coronary intervention is an important quality metric, but prediction models from registry data have only moderate discrimination. We aimed to improve ability to predict 30-day readmission after percutaneous coronary intervention from a previously validated registry-based model.
METHODS AND RESULTS: We matched readmitted to non-readmitted patients in a 1:2 ratio by risk of readmission, and extracted unstructured and unconventional structured data from the electronic medical record, including need for medical interpretation, albumin level, medical nonadherence, previous number of emergency department visits, atrial fibrillation/flutter, syncope/presyncope, end-stage liver disease, malignancy, and anxiety. We assessed differences in rates of these conditions between cases/controls, and estimated their independent association with 30-day readmission using logistic regression conditional on matched groups. Among 9288 percutaneous coronary interventions, we matched 888 readmitted with 1776 non-readmitted patients. In univariate analysis, cases and controls were significantly different with respect to interpreter (7.9% for cases and 5.3% for controls; P=0.009), emergency department visits (1.12 for cases and 0.77 for controls; P<0.001), homelessness (3.2% for cases and 1.6% for controls; P=0.007), anticoagulation (33.9% for cases and 22.1% for controls; P<0.001), atrial fibrillation/flutter (32.7% for cases and 28.9% for controls; P=0.045), presyncope/syncope (27.8% for cases and 21.3% for controls; P<0.001), and anxiety (69.4% for cases and 62.4% for controls; P<0.001). Anticoagulation, emergency department visits, and anxiety were independently associated with readmission.
CONCLUSIONS: Patient characteristics derived from review of the electronic health record can be used to refine risk prediction for hospital readmission after percutaneous coronary intervention.
BACKGROUND: The Dual Antiplatelet Therapy Study is large streamlined clinical trial designed to evaluate antiplatelet treatment strategies in a broadly inclusive population of subjects treated with coronary stents. Whether large streamlined trials can successfully include a representative group of study sites and patients has not been formally assessed.
METHODS AND RESULTS: Within the National Cardiovascular Data Registry CathPCI Registry, we compared characteristics and outcomes of hospitals participating versus not participating in the Dual Antiplatelet Therapy Study. We also compared clinical and procedural characteristics of trial subjects undergoing percutaneous coronary intervention (PCI) with drug-eluting stents to contemporaneous patients within the National Cardiovascular Data Registry CathPCI Registry. Standardized differences between groups were estimated. Between September 2009 and July 2011, 1.1 million PCIs were performed among 1276 hospitals, of which 309 (24.2%) participated in the Dual Antiplatelet Therapy Study. Participating hospitals were larger (468 versus 311 beds), more frequently located in urban settings (61.2% versus 42.6%), and had higher annual PCI volumes (858 versus 378) compared with nonparticipating hospitals, although hospital case mix and procedural outcomes were similar. Compared with CathPCI patients, trial patients undergoing PCI with drug-eluting stents were similar with respect to race, sex, and rates of diabetes mellitus, hypertension, and smoking, although they had lower rates of prior cardiovascular disease.
CONCLUSIONS: Within the Dual Antiplatelet Therapy Study, clinical trial sites had similar patient case mix and clinical outcomes as nonparticipating sites. Although trial participants were representative of PCI patients with respect to race, sex and most comorbidities, they had a lower prevalence of chronic cardiovascular disease compared with registry patients. Although a streamlined cardiovascular clinical trial may successfully involve a large number of hospitals and rapidly enroll a diverse population of patients, differences between eligible patients and those actually enrolled remained.
CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00977938.