Assessing residents' prescribing behavior in renal impairment

Although fitting orders to renal function avoids overdosage and therefore iatrogenic risk, dosage adjustment is rarely made. The objective of this study was to assess residents' prescribing behavior in renal impairment, through a standardized simulated clinical setting.

This criterion-referenced study was carried out in a French teaching hospital. The hospital had 118 residents; 71 of them were asked to complete a questionnaire including four vignettes, simulating drug prescription in four 'patients' with various degrees of renal impairment (16 orders). The patients had an order of gentamicin sulfate, diclofenac sodium, and amlodipine bensylate. For each drug, the resident could maintain the order, discontinue the order, or change the dosage. A fourth drug, enalapril maleate, was to be started, with three possible dosages and the possibility of not prescribing it. The reference chosen for assessment was the Vidal dictionary, which corresponds to the Physician's Desk Reference and is the French reference for prescription.

All the residents approached for the survey accepted the offer to complete the questionnaire. Among the 16 simulated orders, the median number of appropriate orders per resident was nine. Considering the renal function of their patients, 62% of residents wrote an inappropriate order for gentamicin, 42% wrote an inappropriate order for didofenac, and 52% wrote an inappropriate order for enalapril. Although no adjustment to renal function was required, 28% of the residents decreased the dosage of amlodipine and ordered an underdose.

Considering the iatrogenic risk related to the lack of dosage adjustment, attention should be drawn to increasing residents' awareness of dosage adjustment in renal impairment and to providing them with better information on patients' renal function.