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This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Nicola Vitale Maurizio Cotrufo Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vitale, N. Articles by Cotrufo, M. Search for Related Content PubMed Articles by Vitale, N. Articles by Cotrufo, M.

J Thorac Cardiovasc Surg 1995;110:566-567
© 1995 Mosby, Inc.

LETTERS TO THE EDITOR

Mid-term follow-up after heart valve replacement with CarboMedics bileaflet prostheses

Istituto di Cardiochirurgia
Universita d Bari
Piazza Giulio 11
70124 Bari, Italy

Maurizio Cotrufo, MD

Istituto di Cardiochirurgia
Seconda Universita di Napoli
Ospedale V. Monaldi
Via L. Banchi 3
80100 Napoli, Italy

Reply to the Editor:

We appreciate the opportunity to respond to the comments of Dr. Akins regarding our article. ¹ He gave us the benefit of his experience. ²

With regard to linearized rates of valve-related complications, data were analyzed by applying the Mantel-Haenszel test included in the program 1L of the BMDP statistical software package (BMDP Statistical Software, Inc, Los Angeles, Calif.). ³ This test takes into account the number of events for a given time divided by the number of patients followed up for the same time interval. ^3,4 In our study we assumed a 6-month interval. This type of calculation is presented in our article as the curve at the bottom of each graph. The combined and separate linearized rates presented in our report were obtained with this test, by summing up the patient-year incidences of each time interval divided by the total number of time intervals of follow-up. ^3,4 Moreover, linearized rates of each subgroup of patients were calculated including only the patients undergoing that operative procedure. For all these reasons, they would be better defined as linearized incidences than as linearized rates, and we apologize not to have mentioned this statistical aspect in our paper.

On the other hand, linearized rates are generated by the number of events divided by the number of patient-years. As requested by Dr. Akins, we list the linearized rates of our population for the valve-related complications that we have noted for the combined and separate operative procedures (Table I). The rates were calculated according to this latter method.

References

1. de Luca L, Vitale N, Giannolo B, et al. Mid-term follow-up after heart valve replacement with CarboMedics bileaflet prostheses. J THORAC CARDIOVASC SURG 1993;106:1158-65.[Abstract]
   
2. Akins CW. Mechanical cardiac valvular prostheses. Ann Thorac Surg 1991;52:161-72.[Abstract]
   
3. BMDP Program 1L. BMDP statistical software manual. Vol 2. Los Angeles: University of California Press, 1990.
   
4. Colton T. Statistics in medicine. Boston: Little Brown, 1978.
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Nicola Vitale Maurizio Cotrufo Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vitale, N. Articles by Cotrufo, M. Search for Related Content PubMed Articles by Vitale, N. Articles by Cotrufo, M.