Asymptomatic carotid artery disease.

Asymptomatic Carotid Artery Disease To the Editor: Dr. Mohr has provided a valuable review of asymptomatic carotid artery disease.' However, he misquotes the findings of Jonas and Hass. Jonas and Hass concluded that after extracranial arterial surgery for TIA, a stroke complication rate of >2.9% is unacceptable if one wishes to have results that are significantly better than the results for the medical group in the Joint Study. The figure of 2.9% applies only to strokes, not to the combined morbidity-mortality rate as Dr. Mohr states. I have applied that same % analysis used by Jonas and Hass to the total stroke and death rate reported for TIA patients in the Joint Study (table). In the non-surgical group the total morbidity and mortality was 25.9%. In order to reach statistical superiority at the 5% level, the total morbidity and mortality in the surgical group would have to be no more than 16.8%. Subtracting the 15.4% long-term (42 month) morbidity and mortality rate yields an "acceptable" post-operative stroke or death rate of 1.4% or less. As non-surgical patients do not require arteriography, a combined morbidity-mortality rate of over 1.4% for arteriography, endarterectomy, and the post-operative period is unacceptable. It is unlikely that such a low morbidity-mortality rate could be achieved. Robert Karis, M.D. 1247 Marin Avenue Albany, California, 94706 References 1. Mohr JP: Asymptomatic carotid artery disease. Stroke 13: 431^33, 1982 2. Jonas S, Hass WK: An approach the maximal acceptable stroke complication rate after surgery for transient cerebral ischemia (TIA). Stroke 10: 104, 1979 3. Fields WS, Maslenikov V, Meyer JS, Hass WK, Remington RD, Macdonald M: Joint study of extracranial arterial occlusion. V. Progress report of prognosis following surgery or nonsurgical treatment for transient cerebral ischemic attacks and cervical carotid artery lesions. JAMA 211: 1993-2003, 1970