Girard et al. (A-6) conducted a study to identify prognostic factors of improved
ID: 3240404 • Letter: G
Question
Girard et al. (A-6) conducted a study to identify prognostic factors of improved survival after resection of isolated pulmonary metastases (PM) from colorectal cancer. Among the data collected were the survival (in months), status (dead=1 or dead=0, if alive) and dichotomized number of resected PM (ResectedPM=1 or ResectedPM =’>1’) for 77 patients who underwent complete resection at the first thoracic operation.
What are the study questions?
What is the outcome of interest (dependent variable)?
What are the predictors of outcome (independent variables)?
What statistical model was used?
What statistical hypotheses were tested to address the study questions?
Were the null hypotheses rejected at the level 0.05?
What conclusions should be made based on the statistical analysis results?
In addition to summary questions 1-7 answer the following questions:
What is the median survival (with corresponding confidence interval) in the group with ResectedPM=1 and in the group ResectedPM =’>1’?
What is the estimated hazard ratio (with corresponding confidence interval) associated with the difference in survival between patients with ResectedPM=1 vs. ResectedPM =’>1’? What is the meaning?
The PHREG Procedure Type 3 Tests DF Chi-square Pr Ch Effect Resected PM 1 7.0691 0.0078 Analysis of Maximum Likelihood Estimates 95% Hazard Ratio Haza confidence Parameter Standard DF Estimate Error Chi-Square Pr Chisiq Ratio Limits Label Parameter 7.0691 Resected PM 1 1 -0.74879 0.28163 0.0078 0.473 0.272 0.821 ResectedPM 1Explanation / Answer
Girard et al. (A-6) conducted a study to identify prognostic factors of improved survival after resection of isolated pulmonary metastases (PM) from colorectal cancer. Among the data collected were the survival (in months), status (dead=1 or dead=0, if alive) and dichotomized number of resected PM (ResectedPM=1 or ResectedPM =’>1’) for 77 patients who underwent complete resection at the first thoracic operation.
What are the study questions?
To identify prognostic factors of improved survival after resection of isolated pulmonary metastases (PM) from colorectal cancer.
What is the outcome of interest (dependent variable)?
survival time(in months).
What are the predictors of outcome (independent variables)?
number of resected PM
What statistical model was used?
Survival analysis, Cox proportional hazards model is used.
What statistical hypotheses were tested to address the study questions?
number of resected PM affects the survival of the patients.
Were the null hypotheses rejected at the level 0.05?
Calculated chi square=7.0691, P=0.0078 which is < 0.05 level of significance.
Ho is rejected.
What conclusions should be made based on the statistical analysis results?
There is sufficient evidence that number of resected PM affects the survival of the patients
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