Overall, the sensitivity of the D8/17 assay for the 68 patients with Sydenham’s chorea or OCD/tics was 61.8% (42 assays were positive). Of concern, only 12 assays (46.2%) obtained from the 26 Sydenham’s chorea patients were positive, which is significantly lower (z=5.2, p<0.001) than that previously reported for patients with rheumatic fever (89%–100% were D8/17 positive) (5, 6). Thus, the D8/17 assay failed to "diagnose" the majority of the patients with Sydenham’s chorea. Furthermore, the reliability of the assay was suboptimal. Longitudinal observations of 54 subjects tested at random intervals over the study period demonstrated test-retest agreement of 61.1% (N=132) for the 216 samples assayed (kappa=0.18). Of particular concern, agreement was observed in only 48 of 61 split samples (78.7%, kappa=0.48).