• 23
    Dec
  • Influence of Age on Frequency of Vancomycin Dosing: RESULTS part 2

Use of an aminoglycoside was the only variable that was significantly associated with the outcome. Patients with a prescription for an aminoglycoside were more likely to receive q8h dosing than patients without such a prescription (OR 6.7, 95% CI 1.8-25; p = 0.004).
For 7 patients (5%), the vancomycin was prescribed for empiric q8h dosing, whereas 123 patients (94%) had prescrip­tions for empiric q12h dosing (Table 3). The remaining patient (1%) had a prescription for empiric q18h dosing. The average dose per interval was significantly different between the 2 groups: 1.14 g (standard deviation [SD] 0.2) per dose for controls and 1.06 g (SD 0.2) per dose for cases (p < 0.001).

The median time from the start of vancomycin therapy until the first therapeutic level was 6 days (interquartile range [IQR] 7.5 days) for patients receiving q8h dosing and 4 days (IQR 4.0 days) for those receiving q12h dosing (p < 0.001). One hundred and eighteen (90%) of the patients had a quoted target of 10-15 mg/L. For the remaining 13 patients (10%), the targets were 15-20 mg/L or 10-20 mg/L.
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Table 3. Comparison of Clinical Parameters by Dosing Frequency

Dosing Interval; No. (%) of Patients*

Clinical Parameter

Cases: q8h (n = 58)

Controls:
q12h (n


= 73)

p
Value



Age (years) (mean ± SD)




39

±

11.3



47 ± 15



0.001t



Sex (males)



47/58 (81)



53/73 (73)



0.30Ф



Baseline serum creatinine (|jmol/L) (mean ± SD)




58.9

±

16




60.1

±

17.6



0.58t

Baseline
creatinine clearance (mL/min per


70

kg) (mean
± SD)




164

±

48.3




146

±

41.8



0.026t



Weight (kg) (mean ± SD)§




72.6

±

12.9




75.9

±

21.2



0.61t



Empiric vancomycin regimen II



7/131 (5)



123/131

(94)



Dose per interval (g) (mean ± SD)




1.06

±

0.2




1.14

±

0.2



<0.001t

Regimen by agefl < 40 (n = 55)



33 (60)



22 (40)


> 40 (n = 76)



25 (33)



51 (67)



Length of stay (days) (median and IQR)



22 (26.3)



19 (22.5)



Time from start of vancomycin until first therapeutic level (days)
(median and IQR)



6.0 (7.5)



4.0 (4.0)



<0.001**



Increase
in creatinine


> 30%

above
baseline while taking vancomycin



20/58 (34)



22/72 (31)



0.60tt



Change in vancomycin regimen due to increase in trough level or serum
creatinine



13/58 (22)



14/73 (19)



0.65tt

The baseline mean serum creatinine level did not differ between the 2 groups: 58.9 ^mol/L (SD 16) for the q8h group and 60.1 ^mol/L (SD 17.6) for the q12h group (p = 0.578). However, the mean baseline creatinine clearance as calculated by the modified Cockcroft-Gault equation was significantly different: 164 mL/min per 70 kg (SD 48.3) for the q8h group and 146 mL/min per 70 kg (SD 41.8) for the q12h group (p = 0.026). canadian pharmacy viagra

Table 2. Logistic Regression Model of Effects of Predictor Variables on q8h Dosing
Model* OR (95% CI) Patients < 40 years of age who required q8h dosing regimen 3.1 (1.5-6.3)
Patients taking aminoglycosides who required q8h dosing regiment 6.5 (1.8-25.0) CI = confidence interval, OR = odds ratio.
*Predictor variables were diabetes mellitus, sex, and use of aminoglycoside, angiotensin- converting enzyme inhibitors, and nonsteroidal anti-inflammatory drugs. Too few patients were exposed to amphotericin B, contrast dye, or tacrolimus-cyclosporine to allow analysis by logistic regression.
tNo other predictor variables (sex, diabetes mellitus, angiotensin-converting enzyme inhibitors, nonsteroidal anti-inflammatory drugs) had a significant effect on outcome.

A follow-up serum creatinine value was available for 130 of the 131 patients. Of the 58 patients in the q8h group, 20 (34%) experienced an increase in creatinine greater than 30%. Of the 72 patients in the q12h group for whom a follow-up serum creatinine value was available, 22 (31%) experienced a rise in creatinine greater than 30%; for one patient in the q12h group, no follow-up serum creatinine value was available. Thirteen (22%) of the patients in the q8h group and 14 (19%) of those in the q12h group required a change in regimen because of increased predose serum vancomycin level or increased serum creatinine. However, none of these differences were statistically significant.  erectalis

Pharmacists were the professionals responsible for changing the vancomycin regimen to q8h in the vast majority of cases
(54/58 or 93%).

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