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Management Options for Preterm Labour in Canada
MANAGEMENT OPTIONS FOR PRETERM LABOUR
CYPROTERONE ACETATE WITH ETHINYLESTRADIOL
IN CANADA
AS A RISK FACTOR FOR VENOUS THROMBOEMBOLISM: AN EPIDEMIOLOGICAL EVALUATION
To the Editor: To the Editor:
I would like to congratulate Drs Klam and Leduc on their systematic review of the literature regarding the current evidence in support of the various tocolytics. 1 Their findings, which are consistent with the findings of previously published systematic reviews, emphasize the need for large, well-designed, multicentre randomized controlled trials of tocolytic agents. However, I would caution the authors and readers to not interpret the finding of no difference as meaning equivalence or even that effects are similar, for trials that compared a tocolytic with another tocolytic. Most of these trials were exceedingly small and lacked sufficient power to rule out clinically important differences in most outcomes. I agree wholeheartedly with Klam and Leduc that nifedipine appears to be a very promising tocolytic and should be strongly considered for further evaluation in a placebo-controlled trial. However, I would encourage Canadian obstetricians to delay the initiation of such a trial until after the Canadian Preterm Labour Nitroglycerin Trial is completed. I would also like to draw attention to the Canadian Consensus on the Use ofTocolytics for Preterm Labour. 2 As part of the development work for the consensus workshop, we surveyed the participants as to the use of tocolytics in their centres. As the participants represented primarily the academic centres, it would be inaccurate to conclude from our survey that the majority of Canadian obstetricians and gynaecologists used tocolytic drugs for the initial management of preterm labour. Also, I would ask that the authors of the Canadian Consensus, all of whom contributed substantially to the consensus conference preparations and conduct, as well as to the writing and editing of the report, be cited as authors when referencing the report. 2 Mary E. Hannah, MSc, MDCM, FRCSC
I would like to make a comment regarding W. O. Spitzer's article, Cyproterone Acetate with Ethinylestradiol as a Risk Factorfor Venous Thromboembolism, published in fOGC's December 2003 issue. l In this article Professor Spitzer, referring to our study2 as the Parma study, reports data that is not completely correct. In the text and table on page 10 13, the number of venous thromboembolic (VTE) events that occurred in our population is reported as 8 in cyproterone acetate/ethinylestradiol (CPNEE) users and 39 in users of conventional oral contraceptives (OCS). In filct, the number ofYI'E events that occurred in conventional OC users was 29 (of which 2 were extensive superficial thrombophlebitis), while the number ofVfE events among the CPNEE users was probably 10, out of a total of 13 thromboembolic events including ischemic strokes. I met Professor Spitzer when he came to Parma to speak with members of our group and to check our data. Unfortunately, we no longer have the database and were able to retrieve only 86 clinical records out of the original 169. Overall, in our population there were 39 venous and 10 cerebral arterial thromboembolic events in OC users, for an incidence rate of 49 in 59 603 (0.82 per 1000 woman-years) versus 24 in 303 954 (0.08 per 1000) in nonusers (excluding pregnant or puerperal women). Among users oflow-estrogen «50 ~ EE) OCs containing firstand second-generation progestagens, the cumulative incidence rate ofVfE and stroke was 3 in 9361 (0.32 per 1000); among users of QCs containing gestodene it was 12 in 22 700 (0.52 per 1000); among users of QCs containing desogestrel it was 21 in 19 423 (1.08 per 1000), and it was 13 in 8118 (1.60 per 1000) among users of pills containing cyproterone acetate. There was an apparent trend in our study toward an increased thromboembolic risk in users of tbird- and fourth-generation 0Cs compared to the risk in users of first- and second-generation QCs.
Professor, Department of Obstetrics and Gynaecology Sunnybrook and Women's College Health Sciences Centre University of Toronto Toronto, Ontario
Mario Pini, MD Ospedale di Fidenza and University of Parma Fidenza, Italy
REFERENCES
REFERENCES
I. Klam SL, Leduc L Management options for preterm labour in Canada. JObstet Gynaecol Can 2004;26(4):339-45. 2. Hannah M, Amankwah K, Barrett J, Bonin B, Burrows R, Cheng M, et al. The Canadian consensus on the use of tocolytics for preterm labour. J Soc Obstet Gynaecol Can 1995; 17: I089-138.
JOGe.
I. Spitzer WOo Cyproterone acetate with ethinylestradiol as a risk factor for venous thromboembolism: an epidemiological evaluation. JObstet Gynaecol Can 2003;25( 12): 1011-8. 2. Pini M, Scoditti U, Caliumi F, Manotti C, Quintavalla R, Pattacini C, et al. Risk of venous thromboembolism and stroke associated with oral contraceptives. Role of congenital thrombophilias. Recenti Prog Med
1996;87:331-7. JULY 2004
CYPROTERONE ACETATE WITH ETHINYLESTRADIOL
IN CANADA
AS A RISK FACTOR FOR VENOUS THROMBOEMBOLISM: AN EPIDEMIOLOGICAL EVALUATION
To the Editor: To the Editor:
I would like to congratulate Drs Klam and Leduc on their systematic review of the literature regarding the current evidence in support of the various tocolytics. 1 Their findings, which are consistent with the findings of previously published systematic reviews, emphasize the need for large, well-designed, multicentre randomized controlled trials of tocolytic agents. However, I would caution the authors and readers to not interpret the finding of no difference as meaning equivalence or even that effects are similar, for trials that compared a tocolytic with another tocolytic. Most of these trials were exceedingly small and lacked sufficient power to rule out clinically important differences in most outcomes. I agree wholeheartedly with Klam and Leduc that nifedipine appears to be a very promising tocolytic and should be strongly considered for further evaluation in a placebo-controlled trial. However, I would encourage Canadian obstetricians to delay the initiation of such a trial until after the Canadian Preterm Labour Nitroglycerin Trial is completed. I would also like to draw attention to the Canadian Consensus on the Use ofTocolytics for Preterm Labour. 2 As part of the development work for the consensus workshop, we surveyed the participants as to the use of tocolytics in their centres. As the participants represented primarily the academic centres, it would be inaccurate to conclude from our survey that the majority of Canadian obstetricians and gynaecologists used tocolytic drugs for the initial management of preterm labour. Also, I would ask that the authors of the Canadian Consensus, all of whom contributed substantially to the consensus conference preparations and conduct, as well as to the writing and editing of the report, be cited as authors when referencing the report. 2 Mary E. Hannah, MSc, MDCM, FRCSC
I would like to make a comment regarding W. O. Spitzer's article, Cyproterone Acetate with Ethinylestradiol as a Risk Factorfor Venous Thromboembolism, published in fOGC's December 2003 issue. l In this article Professor Spitzer, referring to our study2 as the Parma study, reports data that is not completely correct. In the text and table on page 10 13, the number of venous thromboembolic (VTE) events that occurred in our population is reported as 8 in cyproterone acetate/ethinylestradiol (CPNEE) users and 39 in users of conventional oral contraceptives (OCS). In filct, the number ofYI'E events that occurred in conventional OC users was 29 (of which 2 were extensive superficial thrombophlebitis), while the number ofVfE events among the CPNEE users was probably 10, out of a total of 13 thromboembolic events including ischemic strokes. I met Professor Spitzer when he came to Parma to speak with members of our group and to check our data. Unfortunately, we no longer have the database and were able to retrieve only 86 clinical records out of the original 169. Overall, in our population there were 39 venous and 10 cerebral arterial thromboembolic events in OC users, for an incidence rate of 49 in 59 603 (0.82 per 1000 woman-years) versus 24 in 303 954 (0.08 per 1000) in nonusers (excluding pregnant or puerperal women). Among users oflow-estrogen «50 ~ EE) OCs containing firstand second-generation progestagens, the cumulative incidence rate ofVfE and stroke was 3 in 9361 (0.32 per 1000); among users of QCs containing gestodene it was 12 in 22 700 (0.52 per 1000); among users of QCs containing desogestrel it was 21 in 19 423 (1.08 per 1000), and it was 13 in 8118 (1.60 per 1000) among users of pills containing cyproterone acetate. There was an apparent trend in our study toward an increased thromboembolic risk in users of tbird- and fourth-generation 0Cs compared to the risk in users of first- and second-generation QCs.
Professor, Department of Obstetrics and Gynaecology Sunnybrook and Women's College Health Sciences Centre University of Toronto Toronto, Ontario
Mario Pini, MD Ospedale di Fidenza and University of Parma Fidenza, Italy
REFERENCES
REFERENCES
I. Klam SL, Leduc L Management options for preterm labour in Canada. JObstet Gynaecol Can 2004;26(4):339-45. 2. Hannah M, Amankwah K, Barrett J, Bonin B, Burrows R, Cheng M, et al. The Canadian consensus on the use of tocolytics for preterm labour. J Soc Obstet Gynaecol Can 1995; 17: I089-138.
JOGe.
I. Spitzer WOo Cyproterone acetate with ethinylestradiol as a risk factor for venous thromboembolism: an epidemiological evaluation. JObstet Gynaecol Can 2003;25( 12): 1011-8. 2. Pini M, Scoditti U, Caliumi F, Manotti C, Quintavalla R, Pattacini C, et al. Risk of venous thromboembolism and stroke associated with oral contraceptives. Role of congenital thrombophilias. Recenti Prog Med
1996;87:331-7. JULY 2004