- Email: [email protected]
Incorrect analysis of cesarean skin incision type and wound complications in obese women?
Letters to the Editors devised an 8 step method for MAP-hysterectomy.3 The use of many different procedures may suggest that there is no one best one. After all, individual experience/skill is important. This agrees with our gut feelings and also with the first author’s experience. After 4 decades of front-line practice, the first author realizes his skills are improving with accumulated experience. Our concern is whether society respects the MAP team and its members. Shamshirsaz et al1 stated that 5 years and 100 MAP-hysterectomies may be necessary to become a core member of a MAP team. Obtaining advanced surgical skills requires tremendous effort. A neurosurgeon capable of resecting a posterior fossa brain tumor, an abdominal surgeon skilled in pancreaticodudenectomy, or a cardiac surgeon performing heart transplantation all require individual life-long efforts. Society, patients, and doctors recognize these surgeons as having special skills and respect them not only for their skills but also for their accumulated efforts, which have made their skills a reality. Is an obstetrician capable of MAP-surgery respected similarly? Is the struggle required to develop the requisite skills recognized? Data show that emergent cesarean hysterectomy (including MAP-hysterectomy) results in maternal death in 5.2%,4 a high rate, indicating the morbidity of this condition, regardless if surgery is emergent or planned. We do not intend to compare which requires more effort or which is more important to society, the neuro-, abdominal-, cardiac-, or MAP-surgeon. All appear to be equally important to society. All require tremendous individual efforts by both candidates (for training) and veterans (to maintain their surgical skills). What moves and motivates doctors? Does money, quality of life, respect from society, or something else? The desire to help others by using their medical/surgical knowledge/skills are fundamental for motivation. However, respect from society is also strong motivation. Obstetricians should make
ajog.org society recognize not only the importance of the MAP team but also the struggle by individual members to develop the skills needed. Respect from society will especially encourage young ambitious trainees. Shigeki Matsubara, MD, PhD Hironori Takahashi, MD, PhD Department of Obstetrics and Gynecology Jichi Medical University 3311-1 Shimotsuke Tochigi 329-0498, Japan [email protected] [email protected] Alan Kawarai Lefor, MD, MPH, PhD Department of Surgery Jichi Medical University 3311-1 Shimotsuke Tochigi 329-0498, Japan [email protected] The authors report no conflict of interest.
REFERENCES 1. Shamshirsaz AA, Fox KA, Erfani H, et al. Multidisciplinary team learning in the management of the morbidly adherent placenta: outcome improvements over time. Am J Obstet Gynecol 2017 Feb 16. pii: S00029378(17)30285-5. http://dx.doi.org/10.1016/j.ajog.2017.02.016. [Epub ahead of print]. 2. Matsubara S. Placenta percreta: multidisciplinary team may not be enough. Aust N Z J Obstet Gynaecol 2014;54:291. 3. Matsubara S, Kuwata T, Usui R, et al. Important surgical measures and techniques at cesarean hysterectomy for placenta previa accreta. Acta Obstet Gynecol Scand 2013;92: 372-7. 4. van den Akker T, Brobbel C, Dekkers OM, Bloemenkamp KW. Prevalence, indications, risk indicators, and outcomes of emergency peripartum hysterectomy worldwide: a systematic review and meta-analysis. Obstet Gynecol 2016;128:1281-94. ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog. 2017.03.031
Incorrect analysis of cesarean skin incision type and wound complications in obese women? TO THE EDITORS: We are writing to describe concerns regarding an article.1 We believe that the authors’ analysis is incorrect and thus may be misguiding physicians who, based on this report, have adopted the preferential use of a vertical skin incision for obese women undergoing cesarean delivery. We thought it would be important to send a letter to provide a detailed summary of our concerns to minimize misinformation or misunderstanding. In Table 2, Marrs et al1 report that the proportion of women in the vertical skin incision group with a wound complication was 4.2% (25/597). In the transverse incision group, the proportion of women with a wound complication was 1.7% (43/2603). Based on the data presented in Table 2, 102 American Journal of Obstetrics & Gynecology JULY 2017
vertical skin incision has a crude odds ratio (OR) of 2.53 (95% confidence interval [CI], 1.47e4.28) for wound complications compared to transverse skin incision. In Table 3, the authors report their adjusted multivariable model. They indicate that the adjusted OR for vertical skin incision is 0.32 (95% CI, 0.17e0.62), protective for wound complication and an effect of a similar magnitude in the opposite direction of their unadjusted OR. The authors conclude that vertical skin incision is associated with decreased odds of composite wound complication. Because the effect of skin incision in the authors’ adjusted model was in the opposite direction as the crude OR and because we were performing another analysis within the same data
Letters to the Editors
ajog.org set, we followed the authors’ published methods and reproduced the analysis in software (STATA 14; StataCorp, College Station, TX) using the publicly available MaternalFetal Medicine Unit Cesarean Registry Data. In our reproduced analysis, using the original variable (“ecskin”) in the maternal-fetal medicine unit registry, the adjusted OR for wound complications associated with transverse skin incision was 0.39 (95% CI, 0.21e0.69) designating vertical incision as reference, which is equivalent to a vertical skin incision adjusted OR of 2.56 for wound complications designating transverse skin incision as reference. In other words, transverse skin incision is, in fact, associated with a decreased odds of wound complication compared to vertical skin incision; the exact opposite conclusion of Marrs et al,1 with an effect of similar magnitude but in the opposite direction. In the original data dictionary, this variable is coded as vertical incision ¼ 1 (unexposed) and transverse incision ¼ 2 (exposed). Notably, the coding of “ecskin” is somewhat counterintuitive since “standard of care” (transverse) would typically be coded as baseline or unexposed, ie, 1 in a 1/2 dichotomous variable or 0 in a binary variable. One of us (M.S.) reproduced the analysis initially; another (D.M.S.) confirmed her analytic findings in software (STATA 14; StataCorp). We also reviewed the analysis with a second epidemiologist at our center. We surmise that the authors unintentionally selected vertical incision (coded ¼ 1 in the original data set) as the reference group and transverse (coded ¼ 2) as the exposure group in the multivariable logistic regression analysis command. We feel obligated to inform you of this apparent error and respectfully request that you review our findings and address our concerns. -
REFERENCE 1. Marrs CC, Moussa HN, Sibai BM, et al. The relationship between primary cesarean delivery skin incision type and wound complications in women with morbid obesity. Am J Obstet Gynecol 2014;210:319.e1-4. ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog. 2017.06.012
REPLY We appreciate the opportunity to correct the findings of our prior analysis as identified by Drs Smid and Stamilio. In our logistic analysis, we mistakenly used the incorrect code for “skin incision type” as the referent variable, which inappropriately inverted the odds ratio for wound infection for vertical and transverse incision types. The database error was repeated even with secondary statistical review at the time of the original analysis. At the time, we were surprised by the opposite direction of the “crude” and “adjusted” odds ratios but rationalized that it was due to selection bias associated with factors underlying the surgeon’s choice for vertical or transverse incision. We recognize and admire the statistical expertise of the corresponding authors to identify our error and apologize to the journal editors for our mistake. In the conclusion of our original article discussion section, we stated that our findings emphasize the need for a randomized clinical trial to address this important question and we believe this to remain true. Sean C. Blackwell, MD McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth) Houston, TX
Marcela Smid, MD, MA, MS University of Utah School of Medicine Salt Lake City, UT [email protected]
Caroline Marrs, MD University of Texas Medical Branch Galveston, TX [email protected]
David M. Stamilio, MD, MSCE University of North Carolina Chapel Hill, NC
The authors report no conflict of interest.
The authors report no conflict of interest.
ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog. 2017.06.014
JULY 2017 American Journal of Obstetrics & Gynecology
103
ajog.org society recognize not only the importance of the MAP team but also the struggle by individual members to develop the skills needed. Respect from society will especially encourage young ambitious trainees. Shigeki Matsubara, MD, PhD Hironori Takahashi, MD, PhD Department of Obstetrics and Gynecology Jichi Medical University 3311-1 Shimotsuke Tochigi 329-0498, Japan [email protected] [email protected] Alan Kawarai Lefor, MD, MPH, PhD Department of Surgery Jichi Medical University 3311-1 Shimotsuke Tochigi 329-0498, Japan [email protected] The authors report no conflict of interest.
REFERENCES 1. Shamshirsaz AA, Fox KA, Erfani H, et al. Multidisciplinary team learning in the management of the morbidly adherent placenta: outcome improvements over time. Am J Obstet Gynecol 2017 Feb 16. pii: S00029378(17)30285-5. http://dx.doi.org/10.1016/j.ajog.2017.02.016. [Epub ahead of print]. 2. Matsubara S. Placenta percreta: multidisciplinary team may not be enough. Aust N Z J Obstet Gynaecol 2014;54:291. 3. Matsubara S, Kuwata T, Usui R, et al. Important surgical measures and techniques at cesarean hysterectomy for placenta previa accreta. Acta Obstet Gynecol Scand 2013;92: 372-7. 4. van den Akker T, Brobbel C, Dekkers OM, Bloemenkamp KW. Prevalence, indications, risk indicators, and outcomes of emergency peripartum hysterectomy worldwide: a systematic review and meta-analysis. Obstet Gynecol 2016;128:1281-94. ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog. 2017.03.031
Incorrect analysis of cesarean skin incision type and wound complications in obese women? TO THE EDITORS: We are writing to describe concerns regarding an article.1 We believe that the authors’ analysis is incorrect and thus may be misguiding physicians who, based on this report, have adopted the preferential use of a vertical skin incision for obese women undergoing cesarean delivery. We thought it would be important to send a letter to provide a detailed summary of our concerns to minimize misinformation or misunderstanding. In Table 2, Marrs et al1 report that the proportion of women in the vertical skin incision group with a wound complication was 4.2% (25/597). In the transverse incision group, the proportion of women with a wound complication was 1.7% (43/2603). Based on the data presented in Table 2, 102 American Journal of Obstetrics & Gynecology JULY 2017
vertical skin incision has a crude odds ratio (OR) of 2.53 (95% confidence interval [CI], 1.47e4.28) for wound complications compared to transverse skin incision. In Table 3, the authors report their adjusted multivariable model. They indicate that the adjusted OR for vertical skin incision is 0.32 (95% CI, 0.17e0.62), protective for wound complication and an effect of a similar magnitude in the opposite direction of their unadjusted OR. The authors conclude that vertical skin incision is associated with decreased odds of composite wound complication. Because the effect of skin incision in the authors’ adjusted model was in the opposite direction as the crude OR and because we were performing another analysis within the same data
Letters to the Editors
ajog.org set, we followed the authors’ published methods and reproduced the analysis in software (STATA 14; StataCorp, College Station, TX) using the publicly available MaternalFetal Medicine Unit Cesarean Registry Data. In our reproduced analysis, using the original variable (“ecskin”) in the maternal-fetal medicine unit registry, the adjusted OR for wound complications associated with transverse skin incision was 0.39 (95% CI, 0.21e0.69) designating vertical incision as reference, which is equivalent to a vertical skin incision adjusted OR of 2.56 for wound complications designating transverse skin incision as reference. In other words, transverse skin incision is, in fact, associated with a decreased odds of wound complication compared to vertical skin incision; the exact opposite conclusion of Marrs et al,1 with an effect of similar magnitude but in the opposite direction. In the original data dictionary, this variable is coded as vertical incision ¼ 1 (unexposed) and transverse incision ¼ 2 (exposed). Notably, the coding of “ecskin” is somewhat counterintuitive since “standard of care” (transverse) would typically be coded as baseline or unexposed, ie, 1 in a 1/2 dichotomous variable or 0 in a binary variable. One of us (M.S.) reproduced the analysis initially; another (D.M.S.) confirmed her analytic findings in software (STATA 14; StataCorp). We also reviewed the analysis with a second epidemiologist at our center. We surmise that the authors unintentionally selected vertical incision (coded ¼ 1 in the original data set) as the reference group and transverse (coded ¼ 2) as the exposure group in the multivariable logistic regression analysis command. We feel obligated to inform you of this apparent error and respectfully request that you review our findings and address our concerns. -
REFERENCE 1. Marrs CC, Moussa HN, Sibai BM, et al. The relationship between primary cesarean delivery skin incision type and wound complications in women with morbid obesity. Am J Obstet Gynecol 2014;210:319.e1-4. ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog. 2017.06.012
REPLY We appreciate the opportunity to correct the findings of our prior analysis as identified by Drs Smid and Stamilio. In our logistic analysis, we mistakenly used the incorrect code for “skin incision type” as the referent variable, which inappropriately inverted the odds ratio for wound infection for vertical and transverse incision types. The database error was repeated even with secondary statistical review at the time of the original analysis. At the time, we were surprised by the opposite direction of the “crude” and “adjusted” odds ratios but rationalized that it was due to selection bias associated with factors underlying the surgeon’s choice for vertical or transverse incision. We recognize and admire the statistical expertise of the corresponding authors to identify our error and apologize to the journal editors for our mistake. In the conclusion of our original article discussion section, we stated that our findings emphasize the need for a randomized clinical trial to address this important question and we believe this to remain true. Sean C. Blackwell, MD McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth) Houston, TX
Marcela Smid, MD, MA, MS University of Utah School of Medicine Salt Lake City, UT [email protected]
Caroline Marrs, MD University of Texas Medical Branch Galveston, TX [email protected]
David M. Stamilio, MD, MSCE University of North Carolina Chapel Hill, NC
The authors report no conflict of interest.
The authors report no conflict of interest.
ª 2017 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog. 2017.06.014
JULY 2017 American Journal of Obstetrics & Gynecology
103