Adjusting for observable selection bias in block randomized trials.

In this paper, we propose a model-based approach to detect and adjust for observable selection bias in a randomized clinical trial with two treatments and binary outcomes. The proposed method was evaluated using simulations of a randomized block design in which the investigator favoured the experimental treatment by attempting to enroll stronger patients (with greater probability of treatment success) if the probability of the next treatment being experimental was high, and enroll weak patients (with less probability of treatment success) if the probability of the next treatment being experimental was low. The method allows not only testing for the presence of observable selection bias, but also testing for a difference in treatment effects, adjusting for possible selection bias.

Effect of olanzapine on body composition and energy expenditure in adults with first-episode psychosis.

OBJECTIVE: Weight gain is a commonly observed adverse effect of atypical antipsychotic medications, but associated changes in energy balance and body composition are not well defined. The authors report here the effect of olanzapine on body weight, body composition, resting energy expenditure, and substrate oxidation as well as leptin, insulin, glucose, and lipid levels in a group of outpatient volunteers with first-episode psychosis. METHOD: Nine adults (six men and three women) experiencing their first psychotic episode who had no previous history of antipsychotic drug therapy began a regimen of olanzapine and were studied within 7 weeks and approximately 12 weeks after olanzapine initiation. RESULTS: After approximately 12 weeks of olanzapine therapy, the median increase in body weight was 4.7 kg, a significant increase of 7.3% from first observation. Body fat, measured by dual-energy x-ray absorptiometry, increased significantly, with a propensity for central fat deposition. Lean body mass and bone mineral content did not change. Resting energy expenditure, measured by indirect calorimetry, did not change. Respiratory quotient significantly increased 0.12 with olanzapine and was greatest in those who gained >5% of their initial weight. Fasting insulin, C-peptide, and triglyceride levels significantly increased, but there were no changes in glucose levels; total, high density lipoprotein, or low density lipoprotein cholesterol levels; or leptin levels. CONCLUSIONS: Olanzapine appears to have induced an increase in central body fat deposition, insulin, and triglyceride levels, suggesting the possible development of insulin resistance. The decrease in fat oxidation may be secondary or predispose patients to olanzapine-induced weight gain.

Impact of race on survival in men with metastatic hormone-refractory prostate cancer.

OBJECTIVES: To determine whether blacks with hormone-refractory prostate cancer have shorter survival compared with whites with the same disease. METHODS: Data from eight multicenter trials (four Phase II and four randomized Phase III studies) conducted by the Cancer and Leukemia Group B were combined. Eligible patients had progressive prostate cancer after androgen deprivation therapy (with documented castration levels of testosterone), an Eastern Cooperative Oncology Group performance status of 0 to 2, and adequate hematologic, renal, and hepatic function. The proportional hazards model was used to assess the prognostic importance of race, adjusting for important factors. All statistical tests were two-sided. RESULTS: Of the 1183 patients, 15% were blacks, 45% of patients had a Gleason sum of 8 or greater, and the median age was 71 years. Of the 1183 patients, 35% had measurable disease and 89% had an Eastern Cooperative Oncology Group performance status of 0 to 1. Blacks were younger, had a shorter interval between diagnosis and study entry, and had greater prostate-specific antigen levels, lower hemoglobin levels, and a lower likelihood of prior prostatectomy than whites. The median survival was 15 months (95% confidence interval 12 to 18) for blacks compared with 14 months (95% confidence interval 13 to 15) for whites. In a multivariate analysis, adjusting for age, performance status, presence of visceral disease, hemoglobin, Gleason sum, prostate-specific antigen level, alkaline phosphatase, lactate dehydrogenase, and years since diagnosis, the hazard ratio was 0.85 (95% confidence interval 0.71 to 1.02, P = 0.08) for blacks compared with whites. CONCLUSIONS: No statistically significant difference was found in overall survival between blacks and whites with metastatic hormone-refractory prostate cancer.

A population-based study of the prevalence and influence of gifts to radiation oncologists from pharmaceutical companies and medical equipment manufacturers.

PURPOSE: Hospital-based physicians are responsible for the purchase of expensive equipment. Little is known about the influence of gift giving on their behavior. We wanted to ascertain the prevalence of gift giving from the pharmaceutical industry and medical equipment manufacturers to radiation oncologists and determine whether or not the size of accepted gifts influences their opinions regarding gifts. METHODS AND MATERIALS: A population-based survey of hospital-based physicians conducted between 2002 and 2003. The study population consisted of all radiation oncologists who were members of the American Society of Therapeutic Radiology and Oncology between 2000 and 2001. A random number generator was used to identify 20% of the population. This group was invited by e-mail and conventional mail to complete a Likert scale questionnaire. Those asked to complete the questionnaire electronically were directed to a specially designed web site. RESULTS: Of 640 individuals who were asked to participate, 241 (38%) completed the questionnaire. 96% admitted accepting gifts. The most commonly accepted low value gifts were: pen or pencil (78%), drug samples for patient's use (70%), meal (66%), and a note pad (59%). The most commonly accepted high value gifts were trips to "equipment-users meetings" (15%), honoraria for speaking at a conference (10%), and participation in a conference call (9%). Only 5% of radiation oncologists agreed with the statement "my prescribing practices are affected" by gifts; however, 33% agreed with the statement "I believe that other physicians prescribing practices are affected." Similarly, although only 4% felt that their recommendations concerning purchases of medical equipment are affected by gifts, 19% felt that other physicians would be influenced. A test of the hypothesis that physicians believe that their conduct is less affected than those of their colleagues (i.e., "I am not influenced by gifts but someone else is" was strongly affirmed by a correlation statistic) (p < 0.0001). Of the radiation oncologists surveyed, 74% felt that they should be free to accept gifts of small value, 31% felt they should be free to accept meals or gifts of any type, 16% felt that residency programs should ban free meals provided by companies, 13% felt professional associations should discourage companies from hosting parties at the annual meeting, 17% felt that gift giving should stop, and 66% agreed that clinical information provided by companies provides a useful continuing medical education service. Those who accepted larger gifts were far more likely to disagree with statements such as "professional societies should actively discourage companies from hosting parties and providing free meals and giving gifts to physicians attending the annual meeting" (p = 0.0003) and "the practice of gift giving by companies should stop" (p = 0.0017); they were slightly more likely to agree with statements such as "clinical information provided to radiation oncologists by companies provides a useful continuing medical education service." CONCLUSIONS: To our knowledge, this study represents the first large-scale population based study of a hospital-based specialty and gift giving. This study demonstrates that: (1) Gift giving in radiation oncology is endemic. (2) Although each physician is likely to consider himself or herself immune from being influenced by gift giving, he or she is suspicious that the "next person" is influenced. (3) There is a correlation between the willingness of individual physician to accept gifts of high value and their sympathy toward this practice.

Increased sectioning of pathologic specimens with ductal carcinoma in situ of the breast: are there clinical consequences?

To assess if there has been increased sectioning of pathologic specimens with ductal carcinoma in situ (DCIS), identify sources of this change, and consider the clinical consequences, pathologic data from patients who underwent initial excisional biopsies at our institution and were referred to the radiation oncology department with DCIS from 1992-2002 were retrospectively reviewed. One hundred forty-four of 480 patients with DCIS were eligible for review. Specimen size was recorded as length, to the nearest 0.1 cm, in 3 dimensions. Specimen volume was approximated by the product of the 3 dimensions of the specimen. The primary endpoint was the number of microscopic sections taken from gross specimens, corrected for specimen size. Other analysis included margin status, use of a previous stereotactic needle biopsy, and whether a subsequent repeat excision was performed. Over time, there was an increase in size of the excisional biopsy specimens (mean of 49 cm3 from 1992 to 1994 and 90 cm3 from 2001 to 2002; P = 0.045). Mean numbers of slides per centimeter of specimen were 2.5, 2.7, 3.9, and 5.8 for the intervals 1992-1994, 1995-1997, 1998-2000, and 2001-2002, respectively (P < 0.001 for 1992-1997 vs. 1998-2002). Adjusting for volume, the increase over time in the number of slides per specimen was statistically significant (parameter significance, P < 0.001). For a given volume, the number of slides increased approximately 9.1% per year, on average, during the study period. The positive margin rates were 52%, 46%, 23%, and 25% from 1992 to 1994, from 1995 to 1997, from 1998 to 2000, and from 2001 to 2002, respectively. The degree of sectioning, corrected for specimen length and volume, increased over time.

Long-term changes in pulmonary function tests after definitive radiotherapy for lung cancer.

PURPOSE: To evaluate the long-term changes in pulmonary function tests (PFTs) in patients surviving at least 2 years after definitive radiotherapy (RT) for unresectable lung cancer. METHODS AND MATERIALS: Between 1992 and 2000, 277 patients were enrolled in a prospective clinical study to relate RT-induced changes in lung function with dosimetric and functional metrics. Of these, 128 received definitive RT for lung cancer, and 13 of these had follow-up PFTs for approximately >/=2 years without evidence of recurrent or progressive cancer. PFTs were obtained before RT and approximately every 6 months after RT. The results were evaluated on the basis of each study's "percentage of predicted" of normal values (i.e., adjusted for age, gender, height), and a patient's sequential examinations were compared with their initial study and a percentage of the baseline value was calculated. Follow-up PFTs were available for a median of 38 months (range 23-95). The median patient age was 65 years (range 40-74), 6 patients were men, and 10 were white. Most had Stage T2-T4 and N2-N3. The median RT dose was 71.4 Gy (range 60-73), 6 had twice-daily RT. Four patients received chemotherapy, one concurrent and three neoadjuvant. None of the patients continued to smoke after their treatment. The median pre-RT PFT results were (percentage of predicted) forced expiratory volume in 1 s, 67% (range 24-121); forced vital capacity, 72% (range 45-116); and diffusing capacity of lung for carbon monoxide, 70% (range 41-129). RESULTS: At 6 months, all PFT values had declined, with some stabilization by 1 year. However, after 1 year, a gradual reduction occurred in all three parameters. Ten patients (77%) developed RT-induced respiratory symptoms (2 cough only, 8 dyspnea) at 2-21 months (median 5) after treatment. Two patients required inhalers, another required long-term steroids and oxygen. Of the 8 patients with dyspnea, 7 had an increase in symptoms beyond 2 years. No patient died of RT-induced pulmonary insufficiency. CONCLUSION: RT caused a decline in PFTs that was apparent at 6 months and continued well beyond 1 year. The continued decline in PFTs is suggestive of progressive/evolving RT-induced lung injury. "Late" pulmonary symptoms have also occurred in these patients. Because of the high mortality rate of unresectable lung cancer, few patients can be evaluated for long-term analysis. Additional studies and pooling of data from multiple institutions may help to clarify better the long-term impact of RT on pulmonary function in this subset of patients.