A model for analysis of antibiotic usage in low-income settings

Quantification of antibiotic usage is an important component of antimicrobial stewardship programmes. We aimed to estimate institutional antibiotic usage and costs using methodology and metrics applicable to low-income settings without electronic health records.

The DDD per 100 patient-days (DDDs/100 PDs) of antibiotics used in a calendar year was calculated retrospectively from ward registers and inpatient drug records in general surgical wards of a tertiary hospital. The antibiotics were categorized using the Access, Watch, Reserve classification. The annual expenditure on antibiotics was estimated from price lists of the state medication procurer.

Annual usage of IV co-amoxiclav, cefuroxime and metronidazole was significantly higher than other antibiotics and certain wards showed outlier use of the same. The IV formulations of co-amoxiclav (5-fold), metronidazole (3-fold) and ciprofloxacin (2-fold) were used in excess of the oral formulation. Proportionate antibiotic usage based on the AWaRe category did not vary significantly between wards. Two wards were outliers for annual expenditure/100 PDs. IV clindamycin and meropenem combined accounted for 43.8% of expenditure on antibiotics.

This study demonstrated intra-institutional variations of annual antibiotic usage and related costs. The metric DDD/100 PDs and the methodology used here are suitable for intra- and inter-institutional analyses of antibiotic usage, particularly in low-income settings.