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LETTERS |
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Year : 2005 | Volume
: 51
| Issue : 2 | Page : 153 |
Authors' Reply
M Tayeb, Syed Ahsan Raza, MR Khan, R Azami
Department of Surgery, Faculty of Health Sciences, The Aga Khan University, Stadium Road, P.O. Box 3500, Karachi, Pakistan
Correspondence Address: Syed Ahsan Raza Department of Surgery, Faculty of Health Sciences, The Aga Khan University, Stadium Road, P.O. Box 3500, Karachi Pakistan
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 16006718 
How to cite this article: Tayeb M, Raza SA, Khan M R, Azami R. Authors' Reply. J Postgrad Med 2005;51:153 |
Sir,
We appreciate the comments by Dr. Bhattacharya on our paper to identify the risk factors for conversion to open cholecystectomy (OC). Male gender though pointed out as a major risk factor for conversion; was not identified in our study[1] as a potential risk factor. Hence, we did not include it in the final multivariate model. The goal of our analysis using logistic regression was to present the best fitting yet the most parsimonious model describing the independent relationship of factors with conversion to OC. The criteria for selection of possible factors was based on a p value of less than 0.25 on univariate analysis,[2] and therefore 'gender' was not a good variable to be selected ( P value = 0.39) for the final model. Use of p value of 0.25 as a screening criterion for selection of candidate factor is based on work by Mickey and Greenland on logistic regression. These authors have shown that the use of a more traditional P value of 0.05 on univariate analysis often fails to identify the factors that are known to be important.[3],[4]
Dr. Bhattacharya has in fact extended and clarified other potential risk factors for OC very well. We believe that well-designed trials are needed that will present these risk factors in a more lucid way.
:: References | |  |
1. | Tayeb M, Ahsan RS, Khan MR, Azami R. Conversion from laparoscopic to open cholecystectomy : Multivariate analysis of preoperative risk factors. J Postgrad Med 2005;51:17-20. |
2. | Lemeshow S, Hosmer DW, Jr. A review of goodness of fit statistics for use in the development of logistic regression models. Am J Epidemiol 1982;115:92-106. |
3. | Greenland S, Mickey RM. Re: The impact of confounder selection criteria on effect estimation. Am J Epidemiol 1989;130:1066. [PUBMED] |
4. | Mickey RM, Greenland S. The impact of confounder selection criteria on effect estimation. Am J Epidemiol 1989;129:125-37. [PUBMED] |
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