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A.M. Laties, R.E. Sobel, K. Hvidsten, L. Gorkin; The Incidence of Nonarteritic Anterior Ischemic Optic Neuropathy in Men Using Sildenafil Citrate for Erectile Dysfunction Is Not Different From the Expected Incidence in the General Population . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5646.
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Although the etiology of nonarteritic anterior ischemic optic neuropathy (NAION) is unknown, many of its risk factors are similar to those for erectile dysfunction (ED). We assessed the occurrence of NAION among patients participating in clinical trials of sildenafil citrate and in 2 long–term, postmarketing, population–based observational studies.
We reviewed the data from >13,400 men with ED in 103 clinical trials of sildenafil conducted by Pfizer; from the International Men’s Health Study (IMHS), a prospective cohort study conducted by Pfizer of >3800 men receiving a prescription for sildenafil in Germany, France, Spain, or Sweden; and from the sildenafil Prescription Event Monitoring (PEM) study of >28,000 patients, conducted independently by the Drug Safety Research Unit at the University of Southampton. The PEM consisted of 2 cohorts who received a sildenafil prescription in 1998 and 1999 in the UK National Health Service: Patient number for Cohort I=5601 and Cohort II=22473. We compared the incidence of NAION in these populations of sildenafil users to the estimated annual incidence of NAION in the general population.
No cases of NAION were reported or observed from >13,000 patient–years of observation in the Pfizer clinical trials database. No cases of NAION were observed in nearly 3,000 patient–years of follow–up in the IMHS database. There were no cases of NAION in Cohort I, and a single case of NAION from Cohort II of the PEM. Based on the 1 case of NAION in a total of 35,500 patient–years of observation in the PEM, the unadjusted incidence rate of NAION is 2.8 per 100,000 patient–years. Utilizing data only from Cohort II, the unadjusted annual incidence of NAION is 3.0 cases per 100,000 men per year. The estimated incidence of NAION among men aged ≥50 years in the general population ranges from 2.5 to 11.8 per 100,000 men per year.
With approximately 52,000 patient–years of observation to date, sildenafil is the most extensively studied phosphodiesterase 5 inhibitor. The incidence of NAION among carefully monitored patients receiving sildenafil is not different from that reported to occur among men in the general population.
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