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Julia Brown

Publications and source records attributed to Julia Brown.

9 recordsLinked to original sources
PubMed2005

Minimization--reducing predictability for multi-centre trials whilst retaining balance within centre.

Minimization is often used to assign patients to treatment groups to ensure good balance in patient numbers within centre and other prognostic factors. Balance within centre is preferable since large imbalances between treatment arms may have logistical implications for centres, such as cost and resource implications. However, recent concern over high predictability of treatment allocation by centres when using minimization has caused this method to be questioned. We used data from current clinical trials to assess predictability and summarize subsequent within-centre imbalances with the aim of finding the most effective minimization method for reducing predictability whilst still retaining sufficient balance within centre, when randomization is to one of two treatments. We compared prediction rates and imbalances for deterministic minimization, and minimization incorporating various random elements, p (p=0.95,0.90,0.80,0.75,0.70). We also compared prediction rates and imbalance when centre was and was not included as a stratification factor. Incorporating a random element proved successful in reducing prediction rates whilst minimizing the inevitable increase in within-centre imbalance, whereas excluding centre as a stratification factor incurred major within-centre imbalance. We therefore suggest that minimization can still be used, and that centre can be included as a stratification factor, but a random element has to be incorporated into the minimization algorithm. Minimization incorporating a random element of 0.80 is the most efficient method to use based upon the simulations undertaken in this study of real clinical trial data using different probabilities of allocation.

Algorithms↗
PubMed2005

Predictive value of the pretreatment extent of disease system in hepatoblastoma: results from the International Society of Pediatric Oncology Liver Tumor Study Group SIOPEL-1 study.

PURPOSE: Preoperative staging (pretreatment extent of disease [PRETEXT]) was developed for the first prospective liver tumor study by the International Society of Pediatric Oncology (SIOPEL-1 study; preoperative chemotherapy and delayed surgery). Study aims were to analyze the accuracy and interobserver agreement of PRETEXT and to compare the predictive impact of three currently used staging systems. PATIENTS AND METHODS: Hepatoblastoma (HB) patients younger than 16 years who underwent surgical resection (128 of 154 patients) were analyzed. The centrally reviewed preoperative staging was compared with postoperative pathology (accuracy) in 91 patients (81%), and the local center staging was compared with the central review (interobserver agreement) in 97 patients (86%), using the agreement beyond change method (weighted kappa). The predictive values of the three staging systems were compared in 110 patients (97%) using survival curves and Cox proportional hazard ratio estimates. RESULTS: Preoperative PRETEXT staging compared with pathology was correct in 51%, overstaged in 37%, and understaged in 12% of patients (weighted kappa = 0.44; 95% CI, 0.26 to 0.62). The weighted kappa value of the interobserver agreement was 0.76 (95% CI, 0.64 to 0.88). The Children's Cancer Study Group/Pediatric Oncology Group-based staging system showed no predictive value for survival (P = .516), but the tumor-node-metastasis-based system and PRETEXT system showed good predictive values (P = .0021 and P = .0006, respectively). PRETEXT seemed to be superior in the statistical fit. CONCLUSION: PRETEXT has moderate accuracy with a tendency to overstage patients, shows good interobserver agreement (reproducibility), shows superior predictive value for survival, offers the opportunity to monitor the effect of preoperative therapy, and can also be applied in patients who have not had operations. For comparability reasons, we recommend that all HB patients included in trials also be staged according to PRETEXT.

Child↗
PubMed2005

Association between Helicobacter pylori infection and adult height.

OBJECTIVES: A cross-sectional survey was performed to evaluate the association between H. pylori and adult height. METHODS: H. pylori infection was assessed using a 13C-urea breath test and height measured by a research nurse using a stadiometer in participants between the ages of 40-49 years. RESULTS: Height was measured in 2932/3682 participants that attended and were evaluable. H. pylori infected women were 1.4 cm shorter than uninfected women (95% confidence interval, CI = 0.7-2.1 cm) and this statistically significant difference persisted after adjusting for age, ethnicity, childhood and present socio-economic status (H. pylori positives 0.79 cm shorter; 95%CI: 0.05-1.52 cm). H. pylori positive men were 0.7 cm shorter than uninfected men but this did not reach statistical significance (95% CI: -0.1-1.5 cm). CONCLUSION: Although H. pylori infection is associated with reduced adult height in women, this maybe due to residual confounding.

Adult↗
PubMed2004

The eVALuate study: two parallel randomised trials, one comparing laparoscopic with abdominal hysterectomy, the other comparing laparoscopic with vaginal hysterectomy.

OBJECTIVE: To compare the effects of laparoscopic hysterectomy and abdominal hysterectomy in the abdominal trial, and laparoscopic hysterectomy and vaginal hysterectomy in the vaginal trial. DESIGN: Two parallel, multicentre, randomised trials. SETTING: 28 UK centres and two South African centres. PARTICIPANTS: 1380 women were recruited; 1346 had surgery; 937 were followed up at one year. Primary outcome Rate of major complications. RESULTS: In the abdominal trial laparoscopic hysterectomy was associated with a higher rate of major complications than abdominal hysterectomy (11.1% v 6.2%, P = 0.02; difference 4.9%, 95% confidence interval 0.9% to 9.1%) and the number needed to treat to harm was 20. Laparoscopic hysterectomy also took longer to perform (84 minutes v 50 minutes) but was less painful (visual analogue scale 3.51 v 3.88, P = 0.01) and resulted in a shorter stay in hospital after the operation (3 days v 4 days). Six weeks after the operation, laparoscopic hysterectomy was associated with less pain and better quality of life than abdominal hysterectomy (SF-12, body image scale, and sexual activity questionnaires). In the vaginal trial we found no evidence of a difference in major complication rates between laparoscopic hysterectomy and vaginal hysterectomy (9.8% v 9.5%, P = 0.92; difference 0.3%, -5.2% to 5.8%), and the number needed to treat to harm was 333. We found no evidence of other differences between laparoscopic hysterectomy and vaginal hysterectomy except that laparoscopic hysterectomy took longer to perform (72 minutes v 39 minutes) and was associated with a higher rate of detecting unexpected pathology (16.4% v 4.8%, P = < 0.01). However, this trial was underpowered. CONCLUSIONS: Laparoscopic hysterectomy was associated with a significantly higher rate of major complications than abdominal hysterectomy. It also took longer to perform but was associated with less pain, quicker recovery, and better short term quality of life. The trial comparing vaginal hysterectomy with laparoscopic hysterectomy was underpowered and is inconclusive on the rate of major complications; however, vaginal hysterectomy took less time.

Adult↗
PubMed2004

A practical approach to a multi-level analysis with a sparse binary outcome within a large surgical trial.

OBJECTIVES: To assess the potential source of variation that surgeon may add to patient outcome in a clinical trial of surgical procedures. METHODS: Two large (n = 1380) parallel multicentre randomized surgical trials were undertaken to compare laparoscopically assisted hysterectomy with conventional methods of abdominal and vaginal hysterectomy; involving 43 surgeons. The primary end point of the trial was the occurrence of at least one major complication. Patients were nested within surgeons giving the data set a hierarchical structure. A total of 10% of patients had at least one major complication, that is, a sparse binary outcome variable. A linear mixed logistic regression model (with logit link function) was used to model the probability of a major complication, with surgeon fitted as a random effect. Models were fitted using the method of maximum likelihood in SAS. RESULTS: There were many convergence problems. These were resolved using a variety of approaches including; treating all effects as fixed for the initial model building; modelling the variance of a parameter on a logarithmic scale and centering of continuous covariates. The initial model building process indicated no significant 'type of operation' across surgeon interaction effect in either trial, the 'type of operation' term was highly significant in the abdominal trial, and the 'surgeon' term was not significant in either trial. CONCLUSIONS: The analysis did not find a surgeon effect but it is difficult to conclude that there was not a difference between surgeons. The statistical test may have lacked sufficient power, the variance estimates were small with large standard errors, indicating that the precision of the variance estimates may be questionable.

Humans↗
PubMed2003

High-dose chemotherapy with hematopoietic stem-cell rescue for multiple myeloma.

BACKGROUND: High-dose therapy with supporting autologous stem-cell transplantation remains a controversial treatment for cancer. In multiple myeloma, first-line regimens incorporating high-dose therapy yield higher remission rates than do conventional-dose treatments, but evidence that this translates into improved survival is limited. METHODS: In this multicenter study, the Medical Research Council Myeloma VII Trial, we randomly assigned 407 patients with previously untreated multiple myeloma who were younger than 65 years of age to receive either standard conventional-dose combination chemotherapy or high-dose therapy and an autologous stem-cell transplant. RESULTS: Among the 401 patients who could be evaluated, the rates of complete response were higher in the intensive-therapy group than in the standard-therapy group (44 percent vs. 8 percent, P<0.001). The rates of partial response were similar (42 percent and 40 percent, respectively; P=0.72), and the rates of minimal response were lower in the intensive-therapy group than in the standard-therapy group (3 percent vs. 18 percent, P<0.001). Intention-to-treat analysis showed a higher rate of overall survival (P=0.04 by the log-rank test) and progression-free survival (P<0.001) in the intensive-therapy group than in the standard-therapy group. As compared with standard therapy, intensive treatment increased median survival by almost 1 year (54.1 months [95 percent confidence interval, 44.9 to 65.2] vs. 42.3 months [95 percent confidence interval, 33.1 to 51.6]). There was a trend toward a greater survival benefit in the group of patients with a poor prognosis, as defined by a high beta2-microglobulin level (more than 8 mg per liter). CONCLUSIONS: High-dose therapy with autologous stem-cell rescue is an effective first-line treatment for patients with multiple myeloma who are younger than 65 years of age.

Adult↗
PubMed2002

Surgical view of the treatment of patients with hepatoblastoma: results from the first prospective trial of the International Society of Pediatric Oncology Liver Tumor Study Group.

BACKGROUND: Surgical resection is the cornerstone of treatment for patients with hepatoblastoma (HB). The Society of Pediatric Oncology Liver Tumor Study Group launched its first prospective trial (SIOPEL-1) with the intention to treat all patients with preoperative chemotherapy and delayed surgical resection. The objective of this article was to assess the assumed surgical advantages of primary chemotherapy. METHODS: Between 1990 and 1994, 154 patients age < 16 years with HB were registered on SIOPEL-1. The pretreatment extent of disease was assessed, and, after undergoing biopsy, patients were treated with cisplatin 80 mg/m(2) intravenously over 24 hours and doxorubicin 60 mg/m(2) intravenously over 48 hours by continuous infusion (PLADO). Generally, tumors were resected after four of a total of six courses of PLADO. RESULTS: One hundred twenty eight patients underwent surgical resection (13 patients underwent primary surgery, and 115 patients underwent delayed surgery after PLADO). A pretreatment surgical biopsy was performed in 96 of 128 patients (75%). Biopsy complications occurred in 7 of 96 patients (7%). Twenty-two patients showed pulmonary metastases at the time of diagnosis, and 7 patients underwent thoracotomy. Operative morbidity and mortality were 18% and 5%, respectively. Complete macroscopic surgical resection was achieved in 106 patients (92%), including 6 patients who underwent orthotopic liver transplantation. The actuarial 5-year event free survival (EFS) rate for all 154 patients in the study was 66%, and the overall survival (OS) rate was 75%. For the 115 patients who were included in the surgical analysis that followed the exact protocol, the EFS and OS rates were 75% and 85%, respectively. CONCLUSIONS: Biopsy is a safe procedure and should be performed routinely. Preoperative chemotherapy seems to make tumor resection easier. Reresection of a positive resection margin does not necessarily have to be performed, because postoperative chemotherapy showed good results. Resection of lung metastases can be curative if there is local control of the primary tumor; however, results showed that the patient's prognosis was worse. Surgical morbidity or mortality rates were not necessarily higher in large multicenter studies. More importantly, countries of lesser economic status also can contribute effectively to these trials.

Adolescent↗
PubMed2002

Evaluation of reactive blue 2 derivatives as selective antagonists for P2Y receptors.

P2Y receptor pharmacology is hampered by a lack of subtype selective antagonists. However, a recent study evaluated series of compounds, structurally related to the dye reactive blue 2, for their antagonist selectivity at P2X vs. P2Y receptors. Acid blue 129, acid blue 80, acid blue 25 and acid violet 34 were found to be the most potent of the antagonists studied, at P2Y receptors [Naunyn Schmiedeberg's Arch. Pharmacol. 357 (1998) 111]. In this study, we have determined the ability of these four agents to selectively antagonize inositol phosphate turnover mediated by P2Y1 and P2Y2 receptors that are natively expressed in bovine aortic endothelial (BAE) cells. Acid blue 129, acid blue 80, and acid violet 34 shifted the dose-response curve of the P2Y1 agonist 2-methylthio adenosine trisphosphate (2MeSATP) to the right. Acid blue 129 and acid blue 80 were also very weak antagonists of the P2Y2 agonist uridine 5'-triphosphate (UTP). At 30 and 100 microM, acid violet 34 failed to have any significant effect on the dose-response to UTP. However, at 10 microM, acid violet 34 enhanced the UTP responses. Acid blue 80, acid blue 129 and acid violet 34 are P2Y vs. P2X selective, but show poor selectivity between P2Y1 and P2Y2 receptors and are therefore of limited use in the field of P2Y receptor pharmacology. Furthermore, contrary to previous reports, acid blue 25 is not a P2Y-selective antagonist.

Adenosine Triphosphate↗