Introduction: The population is aging and older adults comprise the
majority of patients in intensive care units. Colistin (COL) has been
reintroduced to treat increasingly common resistant Gram-negative
bacterial infections. Our study aims to investigate the factors
affecting colistin nephrotoxicity in the general population and
geriatric age group. Materials and Method: This retrospective study
included 170 patients, 116 (68.2%) of which were in the geriatric group
(age ≥65). Acute renal failure was evaluated using the RIFLE score.
Firstly, factors associated with COL nephrotoxicity in the general
population were investigated. Then, risk factors for COL nephrotoxicity
were evaluated in the geriatric patient group. Results: 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. In the evaluation of the
geriatric population-based on nephrotoxicity, the initial serum urea and
creatinine levels, immunosuppression, and overall mortality rates were
found to be statistically significant in the group with nephrotoxicity
(p<0.05). Initial serum creatinine level (OR=22.48; 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 independent risk factors associated
with nephrotoxicity in geriatric patients. Conclusion: Advanced age was
found to be a risk factor for COL nephrotoxicity. Caution should be
exercised especially in geriatric patients who have initial serum
creatinine levels close to the upper limit, concomitant use of
nephrotoxic drugs should be avoided and if possible, evaluation should
be made in terms of non-COL treatment options in these patients.