The plantar reflex: A study of observer agreement, sensitivity, and observer bias

The utility of the plantar reflex in modern neurology is controversial. We studied the Babinski, Chaddock, and Oppenheim reflexes in terms of intraobserver, interobserver, and intertest agreement; sensitivity; positive predictive value (PPV); and observer bias. Sixty-two patients and 1,984 reflexes were analyzed. Intraobserver and interobserver agreement were weak (median κ <0.4). Intertest agreement was weak (median κ < 0.4) for all paired reflexes, although highest for the Babinski/Chaddock (0.30) (p < 0.05). There was no evidence of observer bias. Sensitivity was 59.7% for the Babinski, 55.3% for the Chaddock, and 30.0% for the Oppenheim. PPV was 70.3% for the Babinski, 66.5% for the Chaddock, and 61.3% for the Oppenheim. Our results show consistently low observer agreement for the plantar reflex. The Babinski and the Chaddock demonstrated comparable sensitivity and PPV.