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Reply to: Evaluation of postmenopausal bleeding
870 Letters
Reply To the Editors: I appreciate Creinin’s interest in our article. He constructed a different algorithm to account for the false-negative rates of endometrial biopsy and vaginal ultrasonography and calculated even greater cost savings with use of ultrasonography first than in the original algorithm. At least two new assumptions must be made. It must be assumed that all women with incorrect diagnoses will have persistent symptoms and return for reevaluation. Creinin assumed that women with a normal endometrial biopsy specimen as the first test would have a hysteroscopy and curettage as the second test if symptoms persisted. However, following the logic of the original algorithm, alternate use of both screening tests would mean that women with a normal endometrial biopsy specimen as the first test would have a vaginal ultrasonography as the second test if symptoms persisted. Calculating the costs in that case gives an average cost of $253.47 for endometrial biopsy first (an increase of $9.01 for false-negative tests) and $266.06 for vaginal ultrasonography first (an increase of $36.32 for false-negative tests). In this scenario vaginal ultrasonography as the first test actually costs more than endometrial biopsy first. We agree that further clinical studies to compare the diagnostic accuracy and costs of these two tests will help clarify the issue of which test is better as the first test in the evaluation of women with postmenopausal bleeding. Anne M. Weber, MD Department of Gynecology and Obstetrics, Cleveland Clinic Foundation, 9500 Euclid Ave., A81, Cleveland, OH 44195 6/8/89465
Diastolic blood pressure and onset of preeclampsia To the Editors: In their study Sibai et al. (Sibai BM, Ewell M, Levine RJ, Klebanoff MA, Esterlitz J, Catalano PM, et al. Risk factors associated with preeclampsia in healthy nulliparous women. Am J Obstet Gynecol 1997;177:100310) clearly demonstrated an analysis of the risk factors associated with preeclampsia in nulliparous women. Multivariate analysis was performed by means of binary logistic regression with use of different cut points for each risk variable to help the clinical management and the prevention of the disease. Diastolic blood pressure was considered as the main variable to select the study group. The measurements of diastolic blood pressure were all collected before 22 weeks’ gestation, and the authors maintain that the maternal vascular response to placentation is already different between normal pregnancies and those in which preeclampsia develops by 20 weeks’ gestation. Thus they concluded that elevated maternal blood pressure could be an epiphenomenon of this pathologic vascular process. We think that the sample size, as well as the statistical approach, fully supports the clinical conclusions, but we wish to ask Sibai et al. for further information regarding the data analysis. The odds ratio in Table I on page 1006
April 1998 Am J Obstet Gynecol
demonstrated a positive trend of preeclampsia as diastolic blood pressure increased. In Fig. 2 on page 1008 the authors reported the percentage of two different levels of preeclampsia (mild and severe) at cutoff points of diastolic pressure at the time of enrollment in the study. It seems that diastolic pressure is inversely correlated to the incidence of severe preeclampsia compared with mild (2% vs. 5% ratio 0.4 in the category 20 to 50 and 3.5% vs 12% ratio 0.29 in the category 71 to 84, for example). This could be misunderstood by the reader who expects a positive correlation between blood pressure and severity of disease. Further logistic regression could help in evaluating the effect. We maintain that the effect of diastolic blood pressure could also be evaluated by taking into account the time of onset of preeclampsia and could change the conclusion reported in Fig. 2. It could be possible that, at the same level of blood pressure, a mild preeclampsia develops late in the pregnancy whereas a severe preeclampsia develops early. Taking into account preeclampsia as an “event” variable, then a “pseudosurvival” analysis could be useful to study this effect. Kaplan-Meier and Cox algorithms could be beneficial in this approach. We would be grateful for a comment from Sibai et al. regarding our suggested approach. Clinical management could benefited by this further information. Antonio Farina, MD New England Medical Center, #394, 750 Washington St., Boston, MA 02111
Luisa Di Luzio, MD, and Paolo Carinci, MD, PhD Institute of Histology and General Embryology, University of Bologna, Bologna, Italy 6/8/89464
Reply To the Editors: We thank Farina et al. for their interest in our report. Their comments are greatly appreciated. The authors compared the incidence of mild and severe preeclampsia according to diastolic pressure at randomization, suggesting that the diastolic blood pressure is inversely correlated to the incidence of severe preeclampsia. They state that the findings in our Table I and Fig. 2 suggest that diastolic pressure is inversely correlated to the incidence of severe preeclampsia compared with mild preeclampsia, with use of the lowest values and highest values of diastolic pressure. Assuming a Poisson distribution for the counts of mild and severe preeclampsia, the distribution of severe preeclampsia conditional on total preeclampsia follows a binomial distribution, with a proportion of success corresponding to the ratio of the incidence of severe to total preeclampsia and a sample size equal to the count of total preeclampsia. We use the Cochran-Armitage test of trend to distinguish between the null hypothesis that the six different populations determined by diastolic blood pressure at entry to the study have the same underlying
Reply To the Editors: I appreciate Creinin’s interest in our article. He constructed a different algorithm to account for the false-negative rates of endometrial biopsy and vaginal ultrasonography and calculated even greater cost savings with use of ultrasonography first than in the original algorithm. At least two new assumptions must be made. It must be assumed that all women with incorrect diagnoses will have persistent symptoms and return for reevaluation. Creinin assumed that women with a normal endometrial biopsy specimen as the first test would have a hysteroscopy and curettage as the second test if symptoms persisted. However, following the logic of the original algorithm, alternate use of both screening tests would mean that women with a normal endometrial biopsy specimen as the first test would have a vaginal ultrasonography as the second test if symptoms persisted. Calculating the costs in that case gives an average cost of $253.47 for endometrial biopsy first (an increase of $9.01 for false-negative tests) and $266.06 for vaginal ultrasonography first (an increase of $36.32 for false-negative tests). In this scenario vaginal ultrasonography as the first test actually costs more than endometrial biopsy first. We agree that further clinical studies to compare the diagnostic accuracy and costs of these two tests will help clarify the issue of which test is better as the first test in the evaluation of women with postmenopausal bleeding. Anne M. Weber, MD Department of Gynecology and Obstetrics, Cleveland Clinic Foundation, 9500 Euclid Ave., A81, Cleveland, OH 44195 6/8/89465
Diastolic blood pressure and onset of preeclampsia To the Editors: In their study Sibai et al. (Sibai BM, Ewell M, Levine RJ, Klebanoff MA, Esterlitz J, Catalano PM, et al. Risk factors associated with preeclampsia in healthy nulliparous women. Am J Obstet Gynecol 1997;177:100310) clearly demonstrated an analysis of the risk factors associated with preeclampsia in nulliparous women. Multivariate analysis was performed by means of binary logistic regression with use of different cut points for each risk variable to help the clinical management and the prevention of the disease. Diastolic blood pressure was considered as the main variable to select the study group. The measurements of diastolic blood pressure were all collected before 22 weeks’ gestation, and the authors maintain that the maternal vascular response to placentation is already different between normal pregnancies and those in which preeclampsia develops by 20 weeks’ gestation. Thus they concluded that elevated maternal blood pressure could be an epiphenomenon of this pathologic vascular process. We think that the sample size, as well as the statistical approach, fully supports the clinical conclusions, but we wish to ask Sibai et al. for further information regarding the data analysis. The odds ratio in Table I on page 1006
April 1998 Am J Obstet Gynecol
demonstrated a positive trend of preeclampsia as diastolic blood pressure increased. In Fig. 2 on page 1008 the authors reported the percentage of two different levels of preeclampsia (mild and severe) at cutoff points of diastolic pressure at the time of enrollment in the study. It seems that diastolic pressure is inversely correlated to the incidence of severe preeclampsia compared with mild (2% vs. 5% ratio 0.4 in the category 20 to 50 and 3.5% vs 12% ratio 0.29 in the category 71 to 84, for example). This could be misunderstood by the reader who expects a positive correlation between blood pressure and severity of disease. Further logistic regression could help in evaluating the effect. We maintain that the effect of diastolic blood pressure could also be evaluated by taking into account the time of onset of preeclampsia and could change the conclusion reported in Fig. 2. It could be possible that, at the same level of blood pressure, a mild preeclampsia develops late in the pregnancy whereas a severe preeclampsia develops early. Taking into account preeclampsia as an “event” variable, then a “pseudosurvival” analysis could be useful to study this effect. Kaplan-Meier and Cox algorithms could be beneficial in this approach. We would be grateful for a comment from Sibai et al. regarding our suggested approach. Clinical management could benefited by this further information. Antonio Farina, MD New England Medical Center, #394, 750 Washington St., Boston, MA 02111
Luisa Di Luzio, MD, and Paolo Carinci, MD, PhD Institute of Histology and General Embryology, University of Bologna, Bologna, Italy 6/8/89464
Reply To the Editors: We thank Farina et al. for their interest in our report. Their comments are greatly appreciated. The authors compared the incidence of mild and severe preeclampsia according to diastolic pressure at randomization, suggesting that the diastolic blood pressure is inversely correlated to the incidence of severe preeclampsia. They state that the findings in our Table I and Fig. 2 suggest that diastolic pressure is inversely correlated to the incidence of severe preeclampsia compared with mild preeclampsia, with use of the lowest values and highest values of diastolic pressure. Assuming a Poisson distribution for the counts of mild and severe preeclampsia, the distribution of severe preeclampsia conditional on total preeclampsia follows a binomial distribution, with a proportion of success corresponding to the ratio of the incidence of severe to total preeclampsia and a sample size equal to the count of total preeclampsia. We use the Cochran-Armitage test of trend to distinguish between the null hypothesis that the six different populations determined by diastolic blood pressure at entry to the study have the same underlying