Abstract
Background Gram negative pathogens are increasingly resistant to commonly used first line antibiotics and colistin is in most cases the only medicine available. There is very limited information available comparing the effectiveness and costs of low versus high dose colistin with studies showing efficacy with both doses and with variable levels of adverse effects. The absence of a definite dosing strategy makes a model to compare low dose and high dose colistin invaluable in making decisions regarding the appropriate use of colistin. Objective This study was designed to evaluate the cost effectiveness of low versus high dose colistin in the treatment of Pneumonia caused by colistin-only sensitive gram negative bacteria from the perspective of a tertiary care hospital in Saudi Arabia. Setting 300-bed tertiary care hospital in Saudi Arabia. Method A retrospective review was conducted to compare the costs and outcomes of treatment of pneumonia with low versus high dose colistin. The model followed an average patient from initiation of treatment until clinical cure or failure. Main outcome measures The main outcomes were cure, nephrotoxicity, total direct costs per episode, cost per additional cure and cost per nephrotoxicity avoided. Results There was no significant difference between high and low dose colistin with regards to clinical cure (30% vs. 21%; p=0.292). Significantly more patients experienced nephrotoxicity with high versus low dose colistin (30% vs. 8%; p=0.004). With low dose colistin the incremental costs per nephrotoxicity avoided was SAR3056.28. One-way sensitivity analyses did not change the overall results. Conclusion Low dose was not inferior to high dose colistin in terms of clinical cure and had a lower incidence of nephrotoxicity resulting in significant cost avoidance.