Use of renal risk drugs in hospitalized patients with impaired renal function-an underestimated problem?

Background. Inappropriate use of drugs in patients with renal impairment (RI) may be harmful and may have deleterious effects. We aimed to investigate the use of renal risk drugs in such patients in general hospitals and to analyse the relationship to demographic factors, risk factors and occurrence of drug-related problems (DRPs). Methods. Patients admitted to departments of internal medicine and rheumatology in five general hospitals were included. We recorded demographic data, drugs used, drugs described to be a risk in RI (renal risk drugs), relevant medical history, laboratory data and clinical/pharmacological risk factors. We used levels of glomerular filtration rates, calculated by the Modification of Diet in Renal Disease formula to classify patients into five stages of renal function. DRPs were recorded and assessed in multidisciplinary hospital team discussions. Results. Of the 808 included patients, 293 (36%) had normal renal function (stage 1), 314 (39%) had mild RI (stage 2), 160 (20%) had moderate RI (stage 3), 35 (4%) had severe RI (stage 4) and six (0.7%) had kidney failure (stage 5). Mean number of drugs used per patient in patients with RI (stages 3, 4 and 5) and patients evaluated to have adequate renal function relative to drug therapy (stages 1 and 2): on admission 6.2 vs 4.1; started in hospital 4.3 vs 3.9 and total number of renal risk drugs 6.1 vs 4.5. All but six patients with RI stages 3, 4 and 5 used two or more renal risk drugs. 124 (62%) of the patients with RI stages 3, 4 and 5 had DRPs linked to the renal risk drugs, and 26% of the renal risk drugs were associated with DRPs. The most common drug classes associated with DRPs were antibacterials, antithrombotic agents, angiotensin-converting enzyme (ACE) inhibitors, opioids and non-steroidal anti-inflammatory drugs (NSAIDs). Conclusions. Among patients admitted to general hospitals, a considerable proportion had renal impairment. In patients with reduced renal function, renal risk drugs were widely used and often in combination. DRPs were frequently associated with the use of renal risk drugs.