Table 4 Validation and refinement of the spectrum score method to measure antimicrobial de-escalation

Convergent validation of original spectrum score

86.3

96.0

87.5

95.6

Reference standard de-escalation prevalence in vignettes was 24.2%. Route of administration data not included in cases. Mean Likert score was 0.51 points higher for cases where regimens contained ≥ 1 antimicrobial available in a PO dosage form administered on day 4 (p = 0.003).

Refinement exercise to verify that IV to PO conversion impacted expert opinion of de-escalation events

NA

NA

NA

NA

Mean Likert scores for regimens containing similar antimicrobials but differing routes of administration by day 4 was 5.0 (1.5) and 4.6 (1.5) for PO and IV cases (P = 0.002), respectively. Linear regression used to estimate an additional credit to the spectrum score ∆ to account for the group mean differences in Likert score associated with conversion from IV to PO therapy. A 6 point credit was added to spectrum score ∆ values for regimens with >50-100% PO and 3 point credit for regimens >0 but < 50% PO.

Convergent validation of spectrum score method including PO offsets

96.2

93.6

94.4

95.7

Reference standard de-escalation prevalence in vignettes was 53.0%. Route of administration data included in cases and PO credits applied to spectrum score ∆.