Of four markers studied, inhibin A was the only one associated with the risk of stillbirth after adjustment for the other markers and risk factors known before pregnancy But elevated levels of this marker alone had a positive likelihood ratio of just 5.

Positive likelihood ratio = sensitivity/(1--Specificity) or 1.

5 and 1 Irrelevant shifts = LR close to 1 Based on these guidelines, a clinical test was considered to be diagnostically accurate if it had a positive likelihood ratio greater than 10 and/or a negative likelihood ratio less than 0.

The positive likelihood ratio for that range is then the ratio of these 2 ratios, the first equation of Table 2.

The rules were applicable to 1,501 (77%) of patients and had a positive likelihood ratio of 21.

The upper bound of the gray zone is defined by the value of the test associated with the minimal positive likelihood ratio (LR+) that allows ruling in the diagnostic hypothesis, and the lower bound by the maximal negative likelihood ratio (LR-) that allows ruling out the diagnostic hypothesis (Fig.

At a cutoff of 100 pg/mL, B-type natriuretic peptide provides a positive likelihood ratio of 3.

By contrast, the combined evaluation of atypical P-ANCAs and ASCAs had a positive likelihood ratio >5 in almost all studies and >10 in one-half of the studies (see Table 5).