Daniel F. Heitjan

The REMATCH trial: rationale, design, and end points

BACKGROUND Because left ventricular assist devices have recently been approved by the Food and Drug Administration to support the circulation of patients with end-stage heart failure awaiting cardiac transplantation, these devices are increasingly being considered as a potential alternative to biologic cardiac replacement. The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) trial is a multicenter study supported by the National Heart, Lung, and Blood Institute to compare long-term implantation of left ventricular assist devices with optimal medical management for patients with end-stage heart failure who require, but do not qualify to receive cardiac transplantation. METHODS We discuss the rationale for conducting REMATCH, the obstacles to designing this and other randomized surgical trials, the lessons learned in conducting the multicenter pilot study, and the features of the REMATCH study design (objectives, target population, treatments, end points, analysis, and trial organization). CONCLUSIONS We consider what will be learned from REMATCH, expectations for expanding the use of left ventricular assist devices, and future directions for assessing clinical procedures.

Phase I Trial of Docetaxel With Estramustine in Androgen-Independent Prostate Cancer

PURPOSE To evaluate the toxicity, efficacy, and pharmacokinetics of docetaxel when combined with oral estramustine and dexamethasone in a phase I study in patients with progressive metastatic androgen-independent prostate cancer. PATIENTS AND METHODS Thirty-four men were stratified into minimally pretreated (MPT) and extensively pretreated (EPT) groups. Estramustine 280 mg PO tid was administered 1 hour before or 2 hours after meals on days 1 through 5, with escalated doses of docetaxel from 40 to 80 mg/m2 on day 2. Treatment was repeated every 21 days. RESULTS Thirty-four patients were assessable for toxicity and 33 for response. In the MPT patients, dose-limiting myelosuppression was reached at 80 mg/m2, with six patients experiencing grade 3/4 granulocytopenia. In EPT patients, escalation above 70 mg/m2 was not attempted. Fourteen MPT (70%) and six EPT (50%) patients had a > or = 50% decline in serum PSA on two consecutive measurements taken at least 2 weeks apart. The overall 50% PSA response rate was 63% (95% confidence interval [CI], 28% to 81%). Of the 18 patients with bidimensionally measurable disease, five (28%; 95% CI, 11% to 54%) achieved a partial response. At the time of entry onto the study, 15 patients required narcotic analgesics for bone pain; after treatment, eight (53%) discontinued their pain medications. The area under the curve for docetaxel increased linearly from 40 to 70 mg/m2. At 80 mg/m2, the measured area under the curve was 8.37 (standard deviation, 0.724), which was significantly higher than the previously reported values. CONCLUSION The recommended phase II dose of docetaxel combined with estramustine is 70 mg/m2 in MPT patients and 60 mg/m2 in EPT patients. This combination is active in men with androgen-independent prostate cancer.

Hemodynamic and Renal Excretory Effects of Human Brain Natriuretic Peptide Infusion in Patients With Congestive Heart Failure A Double-Blind, Placebo-Controlled, Randomized Crossover Trial

BACKGROUND The pharmacological effects of infusion of human brain natriuretic peptide (hBNP) in patients with severe congestive heart failure have not been characterized previously. METHODS AND RESULTS Twenty patients with severe congestive heart failure were randomized in a double-blind, placebo-controlled, crossover trial to receive incremental 90-minute infusions of hBNP (0.003, 0.01, 0.03, and 0.1 microgram/kg per minute) or placebo on 2 consecutive days. At the highest completed dose of the hBNP, mean pulmonary artery pressure decreased from 38.3 +/- 1.6 to 25.9 +/- 1.7 mm Hg; mean pulmonary capillary wedge pressure decreased from 25.1 +/- 1.1 to 13.2 +/- 1.3 mm Hg; mean right atrial pressure decreased from 10.9 +/- 1 to 4.8 +/- 1.0 mm Hg; mean arterial pressure decreased from 85.2 +/- 2.0 to 74.9 +/- 1.7 mm Hg; and cardiac index increased from 2.0 +/- 0.1 to 2.5 +/- 0.1 L/min per square meter (all P < .01 versus placebo). Urine volume and urine sodium excretion increased significantly during hBNP infusion when compared with placebo infusion (90 +/- 38 versus 67 +/- 27 mL/h and 2.6 +/- 2.4 versus 1.4 +/- 1.2 mEq/h, respectively, both P < .05 versus placebo), whereas creatinine clearance and urinary potassium excretion did not change. CONCLUSIONS Infusion of incremental doses of hBNP is associated with favorable hemodynamic and natriuretic effects in patients with severe congestive heart failure.

Mixed-effects models in psychophysiology

The current methodological policy in Psychophysiology stipulates that repeated-measures designs be analyzed using either multivariate analysis of variance (ANOVA) or repeated-measures ANOVA with the Greenhouse-Geisser or Huynh-Feldt correction. Both techniques lead to appropriate type I error probabilities under general assumptions about the variance-covariance matrix of the data. This report introduces mixed-effects models as an alternative procedure for the analysis of repeated-measures data in Psychophysiology. Mixed-effects models have many advantages over the traditional methods: They handle missing data more effectively and are more efficient, parsimonious, and flexible. We described mixed-effects modeling and illustrated its applicability with a simple example.

Rapid reduction in blood flow to the rat ventral prostate gland after castration: Preliminary evidence that androgens influence prostate size by regulating blood flow to the prostate gland and prostatic endothelial cell survival

Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an animal model of androgen action on the prostate, the rat ventral prostate gland, to determine whether acute androgen withdrawal, by means of castration, might alter the primary blood flow to the prostate gland and for the effects of castration on prostatic endothelial cell viability.

Use of Adjuvant Chemotherapy and Radiation Therapy for Rectal Cancer Among the Elderly: A Population-Based Study

PURPOSE Combined adjuvant fluorouracil (5-FU)-based chemotherapy with radiation is now the standard of care for locally advanced rectal cancer in the United States. We investigated the use of these treatments for stages II and III rectal cancer among the elderly and the effectiveness of these treatments on a population-based scale. PATIENTS AND METHODS The linked Surveillance, Epidemiology, and End-Results-Medicare database was used to identify 1,807 Medicare beneficiaries > or = 65 years of age with stage II or III rectal cancer who underwent surgical resection between 1992 and 1996. We excluded members of a health maintenance organization in the 12 months before or 4 months after their diagnosis and those who died within 4 months of diagnosis. We used multivariate analysis to identify factors associated with combined 5-FU and radiation therapy, and propensity score methodology to determine survival benefit for those treated. RESULTS We found that 37% of patients received both adjuvant 5-FU and radiation therapy, 11% 5-FU alone, and 14% radiation alone. Decreasing age, increasing lymph node positivity, comorbid conditions, and nonblack race were associated with increased probability of treatment with 5-FU and radiation. Combined chemotherapy/radiation therapy was associated with improved survival for stage III (relative risk, 0.71; 95% confidence interval, 0.56 to 0.90), but not for stage II rectal cancer (relative risk, 0.89; 95% confidence interval, 0.70 to 1.14). CONCLUSION The association of combined treatment with improved survival in node-positive disease was similar to that observed in other studies. In the absence of data from well-designed randomized controlled trials, our observational data support efforts on the part of clinicians to make appropriate referrals and provide combined treatment for elderly patients with stage III rectal cancer.

Distinguishing “Missing at Random” and “Missing Completely at Random”

Abstract Missing at random (MAR) and missing completely at random (MCAR) are ignorability conditions—when they hold, they guarantee that certain kinds of inferences may be made without recourse to complicated missing-data modeling. In this article we review the definitions of MAR, MCAR, and their recent generalizations. We apply the definitions in three common incomplete-data examples, demonstrating by simulation the consequences of departures from ignorability. We argue that practitioners who face potentially non-ignorable incomplete data must consider both the mode of inference and the nature of the conditioning when deciding which ignorability condition to invoke.

Effect of Prevention Strategies on Survival and Quality-Adjusted Survival of Women With BRCA1/2 Mutations: An Updated Decision Analysis

PURPOSE This study updates findings regarding the effects of prophylactic surgery, chemoprevention, and surveillance on the survival and quality-adjusted survival of women who test positive for BRCA1/2 mutations. MATERIALS AND METHODS Markov modeling of outcomes was performed in a simulated cohort of 30-year-old women who tested positive for BRCA1/2 mutations. The model incorporated breast and ovarian cancer incidence rates from the literature and mortality rates from the Surveillance, Epidemiology, and End Results Program. Quality adjustment of survival estimates were obtained from a survey of women aged 33 to 50 years. Sensitivity analyses were performed of varied assumptions regarding timing and effects of preventive measures on cancer incidence and adverse effects. RESULTS A 30-year-old woman could prolong her survival beyond that associated with surveillance alone by use of preventive measures: 1.8 years with tamoxifen, 2.6 years with prophylactic oophorectomy, 4.6 years with both tamoxifen and prophylactic oophorectomy, 3.5 years with prophylactic mastectomy, and 4.9 years with both surgeries. She could prolong her quality-adjusted survival by 2.8 years with tamoxifen, 4.4 years with prophylactic oophorectomy, 6.3 years with tamoxifen and oophorectomy, and 2.6 years with mastectomy, or with both surgeries. The benefits of all of these strategies would decrease if they were initiated at later ages. CONCLUSION Women who test positive for BRCA1/2 mutations may derive greater survival and quality adjusted survival benefits than previously reported from chemoprevention, prophylactic surgery, or a combination. Observational studies and clinical trials are needed to verify the results of this analysis of the long-term benefits of preventive strategies among BRCA1/2-positive women.

Allopurinol administered after inducing hypoxia-ischemia reduces brain injury in 7-day-old rats.

ABSTRACT: We determined that treatment of immature rats with allopurinol at 15 min after cerebral hypoxiaischemia reduces brain damage. Seven-d postnatal rats were subjected to right common carotid artery ligation followed by 2.25 h of hypoxia (8% O2). At 15 min of recovery in room air, the rat pups received either allopurinol (135 mg/kg s.c.) or saline. Some of the rats (n = 65) were killed at 42 h of recovery for measurement of cerebral hemispheric water content. Other animals (n = 63) were killed at 30 d for morphologic assessment of the severity of damage. In separate rats, we measured the levels of allopurinol and its metabolites in serum and in the brain around the time of peak serum levels. We also determined the effect of allopurinol on rat pup body temperature. Allopurinol reduced the increase in right hemisphere water content and markedly reduced atrophy. No cavitary lesions were seen in the 31 allopurinol-treated rats, whereas 15 of 32 saline-treated rats had cavitary cerebral lesions. Histologic examination confirmed that the allopurinol-treated rats had less brain injury. Serum allopurinol and oxypurinol peaked between 0.5 and 1 h after allopurinol injection. Their peak serum concentrations at 0.75 h postinjection combined was between 360 and 510 μM. Allopurinol did not lower rectal temperature more than 0.04°C. In conclusion, high-dose allopurinol administered at 15 min of recovery from cerebral hypoxia-ischemia markedly reduces both acute brain edema and long-term cerebral injury in immature rats.

Inference from Coarse Data via Multiple Imputation with Application to Age Heaping

Abstract Multiple imputation is applied to a demographic data set with coarse age measurements for Tanzanian children. The heaped ages are multiply imputed with plausible true ages using (a) a simple naive model and (b) a new, relatively complex model that relates true age to the observed values of heaped age, sex, and anthropometric variables. The imputed true ages are used to create valid inferences under the models and compare inferences across models, thereby revealing sensitivity of inferences to prior specifications, from naive to complex. In addition, diagnostic analyses applied to the imputed data are used to suggest which models appear most appropriate. Because it is not clear just what set of heaping intervals should be used, the models are applied under various assumptions about the heaping: rounding (to the nearest year or half year) versus a combination of rounding and truncation as practiced in the United States, and medium versus wide heaping interval sizes. The most striking conclusions ar...