Avoiding concomitant prescription of drugs with a potential for interaction: mission impossible?

OBJECTIVE: The increased prevalence of multi-drug therapy increases the risk of drug interactions. We conducted a study with the aim of evaluating the prevalence of prescribing potentially interacting drug combinations, their severity, mechanism, and in particular, their clinical relevance, in medical inpatients at two Croatian university hospitals. METHODS: A cross-sectional study was conducted that included all medical inpatients receiving >= 2 drugs. Data were analyzed for 200 predefined drug-drug combinations compiled from the Micromedex data-base and literature. Two rating scales were used, one indicating the severity of a potential drug-drug interaction (pDDI) (minor, moderate, major), and the other assessing its clinical relevance (1: contraindicated; 2: avoidable; 3: consider risk-benefit ratio; 4: hardly avoidable). RESULTS: The prescribing patterns were similar between evaluated hospitals. The prevalence of pDDIs was 46%. The mean number of drugs prescribed per patient was 6.2 (± 95% CI 5.9 - 6.5). Out of 200 predefined pDDIs, 96 were found in our study population with mean 2.8 pDDIs per patient (± 95% CI 2.4 - 3.1). Out of 478 single identified pDDIs, most were of moderate and major severity (56% and 33%, respectively). However, only 9% out of them were considered completely avoidable, 57% were considered hardly avoidable, and for 35% the consideration of risk-benefit ratio was recommended. Most pDDIs were classified as pharmacodynamic by mechanism of interaction (45%). Age and number of prescribed drugs were significant risk factors for prescription of potentially interacting drug combinations (OR 1.01 (± 95% CI 1.001 - 1.03) and OR 1.46 (± 95% CI 1.33 - 1.59), respectively). CONCLUSIONS: Despite the high prevalence of pDDIs, only 1 in 10 was considered avoidable.

Inadequate use of preventive strategies in patients receiving NSAIDs.

OBJECTIVE: Little is known about the factors that influence the decision to use NSAIDs in combination with gastroprotective drugs. The aims of this observational study were to evaluate the extent to which NSAID users are prescribed concomitant gastroprotective drug regimens ('preventive strategies'), and to determine how patient risk factors for NSAID-associated gastrointestinal toxicity and physician prescribing preferences influenced the decision to prescribe a gastroprotective drug in combination with an NSAID. DESIGN AND PATIENTS: The study was conducted on 29 June 2004 and comprised 109 eligible adult patients hospitalised at the Clinical Hospital Center, Zagreb. Use of NSAIDs and gastroprotective drugs, risk factors for NSAID-associated gastrointestinal toxicity, and physician prescribing preferences were monitored throughout the study. RESULTS: Sixty-six percent of patients receiving proton pump inhibitors or histamine H(2)-receptor antagonists with NSAIDs had no risk factors for gastrointestinal toxicity. Furthermore, 29% of patients who used NSAIDs had risk factors for gastrointestinal toxicity but were not receiving gastroprotective drugs. Even though patients at risk of NSAID-associated gastrointestinal complications had higher odds of receiving preventive strategies (odds ratio 1.25), the absolute rate of utilisation of these therapies in at-risk populations was unacceptably low (69%). However, the strongest independent correlation for gastroprotective drug use was the prescribing physician, with an odds ratio of 6.40. CONCLUSION: This study demonstrates that an individual physician's prescribing style largely determines the odds of receiving preventive strategies with NSAID treatment and is more important than the patient's risk factors for gastrointestinal toxicity.