Table 3.
Clinical pharmacokinetic outcomes associated with peak–trough-based versus trough-only-based vancomycin therapeutic drug monitoring approaches
| Variable | Trough-only-monitoring group | Peak–trough-monitoring group | p valuea |
|---|---|---|---|
| (n = 35) | (n = 30) | ||
| Pharmacokinetic parameters at treatment initiation | |||
| Vd (L), mean ± SD | 48.5 ± 10.7 | 51.14 ± 9.96 | 0.311 |
| Ke (h−1), mean ± SD | 0.094 ± 0.05 | 0.089 ± 0.051 | 0.702 |
| Cl (L/h), mean ± SD | 4.15 ± 2.22 | 4.24 ± 2.20 | 0.861 |
| t1/2 (h), median [IQR] | 8.01 [11.12] | 7.23 [9.75] | 0.722 |
| CrCl (L/h), median [IQR] | 6.51 [3.44] | 6.45 [3.12] | 0.374 |
| AUC per initialb dose (mg*h/L), median [IQR] | 227 [195.6] | 228 [273.01] | 0.590 |
| Initialb vancomycin serum concentrations (mg/L), median [IQR] | |||
| Trough-1 | 9 [8.3] | 8.4 [12.9] | 0.732 |
| Peak | 25 [10] | 27.9 [17.8] | 0.863 |
| Random-1 | 18.9 [9.4] | 18 [18.1] | 0.837 |
| Random-2 | 11.9 [8.7] | 11.1 [13.28] | 0.638 |
| Trough-2 | 10.6 [10.5] | 8.9 [15.1] | 0.844 |
| Interpretation of initialb peak vancomycin concentrations, n (%)d | |||
| Therapeutic | 27 (77.1) | 17 (60.7) | 0.158 |
| Non-therapeutic | 8 (22.9) | 11 (39.3) | |
| Interpretation of initialb vancomycin trough concentrations, n (%) | |||
| Therapeutic | 6 (17.1) | 7 (23.3) | 0.534 |
| Non-therapeutic | 29 (82.9) | 23 (76.7) | |
| Minimum number of dose adjustments required to first therapeutic serum concentrations, median [min–max] | 2 [1–5] | 1 [1–3] | 0.105 |
| Overall vancomycin dosing requirements | |||
| Single dose (mg/dose), mean ± SD | 1385.71 ± 530.62 | 1015 ± 332.221 | 0.001 |
| Single dose (mg/kg/dose), mean ± SD | 19.03 ± 7.76 | 14.09 ± 5.68 | 0.005 |
| Total daily dose (mg/day), mean ± SD | 3834.49 ± 1,362.83 | 2907 ± 1,416.08 | 0.009 |
| Total daily dose (mg/kg/day), mean ± SD | 52.83 ± 21.59 | 40.78 ± 21.25 | 0.027 |
| Cumulative doses received (mg), mean ± SD | 26,275 ± 24,190 | 19,753 ± 21,893 | 0.192 |
| Vancomycin dosing interval, n (%) | |||
| Q6 h | 6 (17.1) | 11 (36.7) | 0.091 |
| Q8 h | 16 (45.7) | 12 (40) | |
| Q12 h | 13 (37.1) | 4 (13.4) | |
| Q18 h | 0 (0) | 1 (3.3) | |
| Q24 h | 0 (0) | 1 (3.3) | |
| Q36 h | 0 (0) | 1 (3.3) | |
| Vancomycin infusion duration, n (%) | |||
| Infused over 0.5 h | 1 (2.9) | 0 (0) | 0.297 |
| Infused over 1 h | 19 (54.3) | 22 (73.3) | |
| Infused over 1.5 h | 10 (28.5) | 8 (26.7) | |
| Infused over 2.5 h | 2 (5.7) | 0 (0) | |
| Infused over 3 h | 2 (5.7) | 0 (0) | |
| Infused over 4 h | 1 (2.9) | 0 (0) | |
| AUC per TDM adjusted dose(mg*h/L), median [IQR] | 270 [156.02] | 223 [168.82] | 0.590 |
| AUC24/MIC, median [IQR] | 772 [412.95] | 708 [260.87] | 0.762 |
| Post-dose adjustment peak concentration (mg/L), mean ± SD | 35.94 ± 7.7 | 30.38 ± 5.17 | 0.021 |
| Post-dose adjustment trough concentration (mg/L), mean ± SD | 16.8 ± 3.09 | 15.6 ± 3.49 | 0.596 |
| Interpretation of post-dose adjustmentc peak concentrations, n (%)d | |||
| Therapeutic | 29 (69) | 32 (94.1) | 0.006 |
| Subtherapeutic | 13 (31) | 2 (5.9) | |
| Interpretation of post-dose adjustmentc trough concentrations, n (%) | |||
| Therapeutic | 25 (44.6) | 20 (54.1) | 0.665 |
| Subtherapeutic | 19 (33.9) | 10 (27) | |
| Supratherapeutic | 12 (21.4) | 7 (18.9) | |
aChi-squared test, Mann–Whitney U-test or Student’s t-test
bInitial represents pre-TDM doses and concentrations
c56 dose adjustments were applied in the trough-only arm while 37 dose adjustments were applied in the peak–trough arm
dMissing values