RESULTS
A total of 170 patients were included in the study (98 men, 57.6%). The
median age was 73 (range, 18–95) years. All patients had infections
caused by extremely drug-resistant gram-negative bacterial infections.
The causative bacteria were Acinetobacter baumannii (78.2%),Klebsiella pneumonia (15.9%), and Pseudomonas aeruginosa(5.9%). One hundred eight (78.2%) patients had lower respiratory tract
infection, 48 (28.2%) had blood stream infection, 8 (4.7%) had
surgical site infection, and 6 (3.5%) had urinary tract infection.
Nephrotoxicity was detected in 106 (62.4%) patients. According to the
RIFLE classification, 18 (10.6%) patients were evaluated in the ‘risk’
group, 36 (21.2%) patients in the ‘injury’ group, and 52 (30.6%)
patients in the ‘failure’ group. Sixty-four patients had no risk factors
for the development of nephrotoxicity. Five (4.7%) of the patients who
developed nephrotoxicity required hemodialysis. Nephrotoxicity
classification of elderly and young patients according to the RIFLE
score is shown in Figure 1.
The median (minimum-maximum) age of the patients who developed
nephrotoxicity was 75 (19-95) and 50% were male. The duration of
hospitalization before COL therapy was similar in patients with and
without nephrotoxicity (p=0.109). The prevalence of chronic obstructive
pulmonary disease (COPD) was significantly higher in the nephrotoxicity
group (p=0.02), but there was no significant difference between the two
groups in terms of other comorbid diseases. Initial serum urea and
creatinine levels were significantly higher in the nephrotoxicity group
(p<0.001). APACHE II score, vasopressor agent use, concomitant
nephrotoxic agent use, 28-day mortality, and overall mortality rates
were also higher in the nephrotoxicity group (p<0.05). The
demographic, clinical, and laboratory characteristics of patients based
on nephrotoxicity are given in Table 1.
In multivariable logistic regression analysis, advanced age (odds ratio
[OR]=1.043; 95% confidence interval [CI]: 1.018-1.068; p=0.001)
and initial serum creatinine level (OR=23.122; 95% CI: 3.123-171.217;
p=0.002) were found to be independent risk factors associated with
nephrotoxicity (Table 2).
Nephrotoxicity was observed in 88 of the patients aged ≥ 65 years. When
the patients in the geriatric age group were compared based on
nephrotoxicity, the initial serum urea and creatinine values,
immunosuppression, concomitant nephrotoxic agent use, and overall
mortality rates were found to be statistically higher in patients with
nephrotoxicity (p<0.05) (Table 3). In the same patient group,
initial serum creatinine level (OR=22.489; 95% CI: 2.835-178.426;
p=0.003) and concomitant nephrotoxic agent use (OR=2.516; 95% CI:
1.275-4.963; p=0.008) were identified as independent risk factors
associated with nephrotoxicity (Table 4).
Comparison between younger and older patients who developed
nephrotoxicity showed that the older group had significantly higher
APACHE II score, vasopressor agent use, and 14-day, 28-day, and overall
mortality rates (p<0.05) (Table 5). There was no significance
between the two groups in terms of initial and end-treatment serum urea
and creatinine levels, concomitant nephrotoxic agent use, and
hemodialysis need.
31.8% (n=54) of the cases were in young (age 18-64 years) and 68.2%
(n=116) were in geriatric group (age ≥ 65 years). When the geriatric and
younger patients were compared in terms of comorbid diseases, the
incidence of COPD and cardiac diseases were significantly higher in the
geriatric group (p<0.05). When nephrotoxicity rates were
compared between the younger and geriatric groups, the rate was
significantly higher in the geriatric group (p<0.001). Also,
initial serum urea and creatinine, end-treatment urea and creatinine
concentrations, APACHE II score, the rate of vasopressor agent use,
14-day, 28-day, and overall mortality rates were found significantly
higher in the geriatric group (p<0.05) (Table 6).