Table 1:

Accuracy of formula to predict the appropriate needle length to use in the confirmation samplea

Actual SCDCorrectIncorrect
<3.5 inches28/31 (90%)b3/31 (10%)c
>3.5 inches7/7 (100%)c0 (0%)
Total35/38 (92%)3/38 (8%)

  • ↵a Accuracy of formula needle-length prediction, 3.5 or 5 inches. In 7/45 patients, the actual SCD was 3.5 inches; our formula predicted a 5-inch needle in 3/7 (43%) patients and a 3.5-inch needle in 4/7 (57%) patients.

  • ↵b Predicted 3.5-inch needle.

  • ↵c Predicted 5-inch needle.