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Treatment Sequence (treatment + sequence)

Distribution by Scientific Domains
Mathematics and Statistics66%
Medical Sciences33%

Selected Abstracts

Estimation of the Causal Effects on Survival of Two-Stage Nonrandomized Treatment Sequences for Recurrent Diseases

BIOMETRICS, Issue 3 2006
Xuelin Huang
Summary In the treatment of cancer, patients commonly receive a variety of sequential treatments. The initial treatments administered following diagnosis can vary, as well as subsequent salvage regimens given after disease recurrence. This article considers the situation where neither initial treatments nor salvage treatments are randomized. Assuming there are no unmeasured confounders, we estimate the joint causal effects on survival of initial and salvage treatments, that is, the effects of two-stage treatment sequences. For each individual treatment sequence, we estimate the survival distribution function and the mean restricted survival time. Different treatment sequences are then compared using these estimates and their corresponding covariances. Simulation studies were conducted to evaluate the performance of the methods, including their sensitivity to the violation of the assumption of no unmeasured confounders. The methods are illustrated by a retrospective study of patients with soft tissue sarcoma, which motivated this research. [source]

Times to pain relief and pain freedom with rizatriptan 10 mg and other oral triptans

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 7 2007
D. S. Ng-Mak
Summary Background:, In the clinical trial setting, oral rizatriptan 10 mg has greater efficacy than other oral triptans in freedom from migraine headache pain 2 h after dosing. Objective:, The study objective is to compare the effectiveness of rizatriptan 10 mg and other oral triptans for acute migraine attack in a naturalistic setting. Methods:, A total of 673 patients took rizatriptan 10 mg or their usual-care oral triptans for two migraine attacks in a sequential, cross-over manner and recorded outcomes using a diary and a stopwatch. Mean and median times to pain relief (PR) and pain freedom (PF) for rizatriptan and other oral triptans were compared. The effect of rizatriptan on times to PR and PF, adjusting for potential confounding factors (treatment sequence, treatment order and use of rescue medication), was computed via a Cox proportional hazard model. Results:, Significantly, more patients taking rizatriptan achieved both PR and PF within 2 h after dosing than other oral triptans. Times to PR and PF were shorter with rizatriptan than with other oral triptans (median time to PR: 45 vs. 52 min, p < 0.0001; median time to PF: 100 vs. 124 min, p < 0.0001). The adjusted proportional hazard ratios (rizatriptan vs. other oral triptans) for times to PR and PF were 1.32 (95% CI: 1.22,1.44) and 1.27 (95% CI: 1.16,1.39) respectively. Conclusion:, The times to PR and PF in a ,naturalistic' setting were significantly shorter for patients treating a migraine attack with rizatriptan 10 mg than with other oral triptans. [source]

Estimation of the Causal Effects on Survival of Two-Stage Nonrandomized Treatment Sequences for Recurrent Diseases

BIOMETRICS, Issue 3 2006
Xuelin Huang
Summary In the treatment of cancer, patients commonly receive a variety of sequential treatments. The initial treatments administered following diagnosis can vary, as well as subsequent salvage regimens given after disease recurrence. This article considers the situation where neither initial treatments nor salvage treatments are randomized. Assuming there are no unmeasured confounders, we estimate the joint causal effects on survival of initial and salvage treatments, that is, the effects of two-stage treatment sequences. For each individual treatment sequence, we estimate the survival distribution function and the mean restricted survival time. Different treatment sequences are then compared using these estimates and their corresponding covariances. Simulation studies were conducted to evaluate the performance of the methods, including their sensitivity to the violation of the assumption of no unmeasured confounders. The methods are illustrated by a retrospective study of patients with soft tissue sarcoma, which motivated this research. [source]

Randomized phase 2 study of irinotecan plus cisplatin versus gemcitabine plus vinorelbine as first-line chemotherapy with second-line crossover in patients with advanced nonsmall cell lung cancer

CANCER, Issue 2 2008
Ji-Youn Han MD
Abstract BACKGROUND. The current study was performed to compare the nonplatinum-based combination of gemcitabine and vinorelbine (GV) with the combination of irinotecan and cisplatin (IP) as first-line chemotherapy with second-line crossover in patients with advanced nonsmall cell lung cancer (NSCLC). METHODS. Patients were randomly assigned to received either irinotecan at a dose of 65 mg/m2 plus cisplatin at a dose of 30 mg/m2 (Arm A) or gemcitabine at a dose of 900 mg/m2 plus vinorelbine at a dose of 25 mg/m2 (Arm B), each of which was administered on Days 1 and 8 every 3 weeks as the first-line therapy followed by crossover at the time of disease progression. RESULTS. A total of 146 patients were enrolled (75 patients in Arm A and 71 patients in Arm B); 138 patients were evaluable for tumor response and toxicity. During first-line therapy, IP was found to result in more grade 2+ nausea and vomiting (toxicity was graded according to the National Cancer Institute Common Toxicity Criteria [version 2.0]) (41% vs 12%; P = .0001) and alopecia (36% vs 10%; P = .0003). Pneumonitis was noted only with GV therapy (7% vs 0%; P = .058). During second-line therapy, IP was found to result in more grade 3 diarrhea (17% vs 2%; P = .039) and GV featured more cases of grade 3+ neutropenia (78% vs 40%; P = .0003). IP tended to generate more tumor responses (38% vs 26% as first-line therapy, and 30% vs 13% as second-line therapy) compared with GV. IP also demonstrated a favorable trend in median progression-free survival (4.6 months vs 3.8 months as first-line therapy and 4.5 months vs 2.6 months as second-line therapy) and overall survival (15.9 months vs 13.1 months; P = .3), but this difference was not statistically significant. The majority of patients who were refractory to IP also failed to respond to GV in the second-line setting. CONCLUSIONS. The platinum-based IP regimen appeared to be superior to the GV combination in terms of response rate. However, given the similar survival and better tolerability of the nonplatinum GV regimen, either treatment sequence would appear to be acceptable for the treatment of patients with advanced NSCLC. Cancer 2008. © 2008 American Cancer Society. [source]

Risk Factor Adjustment in Marginal Structural Model Estimation of Optimal Treatment Regimes

BIOMETRICAL JOURNAL, Issue 5 2009
Erica E. M. Moodie
Abstract Marginal structural models (MSMs) are an increasingly popular tool, particularly in epidemiological applications, to handle the problem of time-varying confounding by intermediate variables when studying the effect of sequences of exposures. Considerable attention has been devoted to the optimal choice of treatment model for propensity score-based methods and, more recently, to variable selection in the treatment model for inverse weighting in MSMs. However, little attention has been paid to the modeling of the outcome of interest, particularly with respect to the best use of purely predictive, non-confounding variables in MSMs. Four modeling approaches are investigated in the context of both static treatment sequences and optimal dynamic treatment rules with the goal of estimating a marginal effect with the least error, both in terms of bias and variability. [source]

Estimation of the Causal Effects on Survival of Two-Stage Nonrandomized Treatment Sequences for Recurrent Diseases

BIOMETRICS, Issue 3 2006
Xuelin Huang
Summary In the treatment of cancer, patients commonly receive a variety of sequential treatments. The initial treatments administered following diagnosis can vary, as well as subsequent salvage regimens given after disease recurrence. This article considers the situation where neither initial treatments nor salvage treatments are randomized. Assuming there are no unmeasured confounders, we estimate the joint causal effects on survival of initial and salvage treatments, that is, the effects of two-stage treatment sequences. For each individual treatment sequence, we estimate the survival distribution function and the mean restricted survival time. Different treatment sequences are then compared using these estimates and their corresponding covariances. Simulation studies were conducted to evaluate the performance of the methods, including their sensitivity to the violation of the assumption of no unmeasured confounders. The methods are illustrated by a retrospective study of patients with soft tissue sarcoma, which motivated this research. [source]