Sir.—Taubman et al1 in the January 1989 issue of AJDC discuss an extremely important issue—use of a rapid latex agglutination test for the detection of group A β-hemolytic streptococcal pharyngitis in an office setting. Their study design demonstrates the importance of comparing a new test with "the gold standard" (ie, a reference laboratory culture) as well as with the customary test (ie, throat cultures incubated and interpreted in the pediatric office). The authors introduce a term, "percent of false-negative results (% FN*)," that they define as follows:
where TN indicates true negatives; TP, true positives; and FP, false positives.
In a situation like this, the risk of undetected group A β-hemolytic streptococcal pharyngitis (ie, the false-negative tests) is usually communicated by the negative predictive value (PVneg) of the test, an established and frequently used term in clinical epidemiology. If the authors wish to refer to the proportion of