The Impact of the Revised Case Definition of AIDS

To the Editor.—  Since August 1987, when the Centers for Disease Control introduced the new criteria for acquired immunodeficiency syndrome (AIDS) case definition,¹ several attempts have been made to assess the impact on surveillance data. Stehr-Green et al² retrospectively studied 630 hemophiliacs and reported a 24% cumulative increase. Rutherford et al³ found a 19% increase in reporting when using the new definition. Gatell et al⁴ reported that 19.6% of their cumulated clinical series of patients with AIDS met the 1987 definition only because they had some clinical form of tuberculosis.Our registry systematically collects information on all patients with AIDS diagnosed in Catalonia (an autonomous region in Northeast Spain), covering a population of about 6 million inhabitants. The 1987 case definition criteria were introduced for surveillance purposes in January 1988. Up to the first week of April 1988, three hundred twenty-four cases meeting the old definition