Prevalence and predictors of potential drug-drug interactions in Regione Emilia-Romagna, Italy

Prevalence and typology of potential drug interactions occurring in primary care patients

PURPOSE

To investigate the prevalence and types of potential drug interactions in primary care patients to detect risky prescriptions as an essential condition to design intervention policies leading to an improvement in patient safety.

METHODS

Cross-sectional descriptive study.

SETTING

Two areas in Spain comprising 715,661 inhabitants.

PATIENTS

430,525 subjects with electronic medical records and assigned to a family doctor regularly updating them.

RESULTS

On a random day, 29.4% of the population was taking medication. Of these, 73.9% were at risk of suffering interactions, and these were found in 20.6% of them. The amount of interactions was higher among people with chronic conditions, the elderly, females and polymedicated patients. From the total of interactions, 55.1% belonged to the highest clinical relevance 'A' level, and 28.3% should have been avoided. The active ingredients primarily involved were hydrochlorothiazide and ibuprofen and, when focusing on those that should be avoided, omeprazole and acenocoumarol. The most frequent 'A' interaction that should be avoided was between non-conjugated excreted benzodiazepines and proton-pump inhibitors, followed by some NSAIDs and diuretics.

CONCLUSIONS

1 in 20 Spanish citizens is currently undergoing a potential drug interaction, including a high rate of clinically relevant ones that should be avoided. These results confirm the existence of a serious safety issue that should be approached and where all parties involved (physicians, health services, medical societies and patients) must do our bit to improve. Health services should foster the implementation of prescription alert systems linked with electronic medical records including clinical data.

Drug-drug interactions in general hospital and psychiatric hospital in-patients prescribed psychotropic medications

Abstract Objectives. Drug-drug interactions (DDIs) present a serious, ever increasing clinical problem. Previous studies identified DDIs among psychiatric inpatients prescribed psychotropics, but none have focused on psychotropics prescribed to General Hospital inpatients. This study aimed to identify: putative drug-drug interactions; mechanisms; potential seriousness among patients prescribed psychotropes in both psychiatric and general hospital inpatients settings. We hypothesised that potential interactions per person would be greater in General Hospital inpatients on psychotropics, due to polypharmacy. Method. We surveyed psychotropic prescribing in hospital wards in a public sector mental health organisation and a 500-bed general hospital. Ward pharmacists collected drug prescription data. A computer based protocol evaluated DDIs. Results. A total of 7.4% of General Hospital inpatients and 100% of Psychiatric Unit inpatients surveyed were prescribed psychotropic medication. The General Hospital group had significantly more potential interactions per person (3.0) than Psychiatric inpatients (1.3) (P<0.05). There were significantly more potentially serious interactions in the general hospital group (P<0.025). Conclusions. DDIs affect those prescribed psychotropics in both General and Psychiatric Hospitals. The General Hospital patients had a higher number per person and more serious potential interactions, yet are often poorly served by psychiatric services, suggesting that liaison psychiatrists have a role in physician education and DDI assessment.

Using explicit criteria to evaluate the quality of prescribing in elderly Italian outpatients: a cohort study

BACKGROUND AND OBJECTIVE

Inappropriate prescribing in the elderly population is a well-recognized problem in public health. The Beers criteria have been widely used to evaluate the quality of prescribing for the elderly. However, because the Beers criteria were developed in the United States, they are not fully applicable in Italy. The purpose of this study was to establish explicit criteria for potentially inappropriate medication prescribing (PIP) for the elderly and assess the prevalence of and factors associated with PIP among elderly residents in the Local Health Unit of Parma, Italy according to the developed criteria.

METHODS

A nine-member expert panel was convened to identify a list of inappropriate medications reflecting the Italian prescribing habits. The panel decided to refine and update the 2002 Beers criteria. Consensus through a Nominal Group Technique was reached to classify the identified 23 inappropriate medications into three categories: 17 medications to be always avoided, three medications rarely appropriate, and three medications with some indications but often misused. A retrospective cohort study using the 2006 Parma Local Health Unit automated outpatient prescriptions database was conducted. The cohort comprised 91 741 elderly individuals >or=65 years with at least one prescription medication. PIP was defined as having a prescription claim for at least one inappropriate medication.

RESULTS AND DISCUSSION

A total of 23 662 elderly in the cohort (25.8%) had at least one PIP. Of these, 14.1% received prescriptions for two medications of concern, and 2.0% for three or more. Using the expert panel's categories, 59.2% of the elderly receiving PIP had prescriptions for drugs that should always be avoided, 33.9% for rarely appropriate drugs, and 19.1% for drugs that have some indications but are often misused. Non-steroidal anti-inflammatory drugs (35.7% of subjects) were the most frequently occurring PIP, followed by ticlopidine (17.6%), doxazosin (15.5%), and amiodarone (13.6%). Female, older age, overall number of drugs prescribed, greater number of chronic conditions were factors associated with greater odds of receiving PIP.

CONCLUSION

Via the developed criteria, the study corroborates that PIP among elderly outpatients is a substantial issue in Parma Local Health Unit, Italy. Knowledge of the prevalence of PIP and associated factors should gear efforts to develop strategies to reduce PIP in outpatient settings in Italy.

Epidemiology of suboptimal prescribing in older, community dwellers: a two-wave, population-based survey in Dicomano, Italy

BACKGROUND

Because of co-morbidity, older persons are often exposed to use of an excessive number of drugs, which per se implies also use of inappropriate drugs or of potentially interacting drugs ('suboptimal prescribing'). Time trends of suboptimal prescribing in older, community dwellers have been poorly investigated, particularly in Italy.

OBJECTIVE

To evaluate the time-course modification of suboptimal prescribing in older, community dwellers.

METHODS

We conducted a study on an Italian cohort of older (aged>or=65 years), community dwellers for whom data were collected in a two-wave (1995 and 1999), population-based survey. Suboptimal prescribing was defined as occurrence of polypharmacy (>or=5 medications), prescription of inappropriate medications (according to 1991 Beers' criteria) and prescription of potentially interacting drugs (as identified by the Micromedex Drug-Reax system). All outcome variables were modelled as continuous and dichotomous.

RESULTS

In 568 participants (59.9% women, mean+/-standard error age 72.7+/-0.2 years), polypharmacy and potentially interacting drugs were more prevalent in 1999 than in 1995, while prevalence of inappropriate drugs was lower in 1999. The proportion of participants receiving polypharmacy was nearly 3-fold greater in 1999 than in 1995 (21.6% vs 8.8%; p<0.001). After adjustment for disability, coronary artery disease/stroke, heart failure and other co-morbidities, polypharmacy was twice as prevalent in 1999 as in 1995, with a mean increase of 0.5 drugs per participant. In contrast, in models adjusted for the same variables and also for polypharmacy, inappropriate prescribing was reduced (60% lower prevalence, 0.06 mean reduction in prescriptions per participant) in 1999 compared with 1995. In multivariable models, no change was observed in the number of potentially interacting prescriptions.

CONCLUSIONS

Between 1995 and 1999, the number of prescriptions received by a cohort of older, community dwellers increased substantially, even after controlling for co-morbidity. On the other hand, when controlling for polypharmacy, other indicators of suboptimal prescribing remained unaffected or even decreased, suggesting that even increasing levels of polypharmacy do not necessarily imply other forms of suboptimal prescribing among older persons.

Potential drug-drug interactions and radiodiagnostic procedures: an in-hospital survey

OBJECTIVES

To evaluate the type, frequency, severity and predictors of potential Drug-Drug Interactions (DDIs) in a cohort of patients undergoing radiodiagnostic procedures.

SETTING

Eight Radiology wards located in Tuscany (Italy).

METHODS

All participants exposed to at least two medications were included in the analysis. DDIs were grouped according to their severity as 'minor', 'moderate' or 'major'. A logistic model was used to estimate Odds Ratios and 95% Confidence Intervals for all predictors of potential DDI.

MAIN OUTCOME MEASURES

Type and predictors of potential DDI in a cohort of patients undergoing radiodiagnostic procedures.

RESULTS

One-thousand-and-two subjects (57.6% females; mean age: 67.3 +/- 12.2) entered the analysis, and 46.1% of them incurred in a potential DDI (78.9% 'moderate' in severity). The combination of allopurinol and ACE-inhibitors was the most frequent (21/153) among major potential DDIs, while steroids were involved in all cases of potential DDI due to premedication. Co-morbidity, number of co-medications, advanced age and premedication use increased the risk of potential DDI; a protective role was found for positive history of allergy. When the analysis was restricted to subjects with premedication (n = 93), only 12.9% of them reported a potential DDI directly attributable to premedication drugs.

CONCLUSIONS

Among patients undergoing radiological examination, types and predictors of potential DDIs appeared in agreement with other kind of in-hospital populations. Premedication revealed to be a proxy predictor for potential DDIs. Considering the poor capability of the prescriber in recognizing interactions, their systematic evaluation (using an informatics tool) in patients undergoing radiological examination might be helpful in preventing the occurrence of clinically relevant DDIs.

Predicting the clinical relevance of drug interactions from pre-approval studies

Drug interactions (DIs) may result in adverse drug events that could be prevented, but in many cases the available information on potential DIs is not easily transferable to clinical practice. The majority of studies date from preclinical or premarketing phases, using animals or human-derived sources that may not accurately reflect the growing clinical complexity of high-risk populations, such as the elderly, women, children, patients with chronic disease, polytherapy and impaired organ functions. Thus, at the time of approval of a new drug the information in the summary of product characteristics refers to potential DIs, but lacks specific management recommendations and is of limited clinical utility. Therefore, we set out to review in vitro and in vivo methods to predict and quantify potential DIs, to see whether these studies could help the physician tackle daily problems of the assessment and choice of combined drug therapies, and to propose, from a clinical point of view, how premarketing studies could be improved so as to help the physician at the patient's bedside. Preclinical and premarketing study design needs to be improved to make information easily accessible and clinically transferable. Studies should also take into account appropriate sample size, duration, co-morbidity, number of coadministered drugs, within- and between-subject variability, specific at-risk populations and/or drugs with a relatively narrow therapeutic window, and clinical endpoints. After premarketing development in situations where there is potential high risk of serious adverse events, specific phase IV studies (and/or active pharmacovigilance studies) should be required to monitor and quantitatively assess their clinical impact.

[Using information technology to improve drug safety in primary care]

PURPOSE

To help family doctors to detect and prevent problems related to drug-drug interactions in order to attain a higher quality prescription and an improvement in patient safety.

METHODS

Uncontrolled study of an intervention based on quality evaluation and improvement methods.

SETTING

Two health areas in Murcia Region (Spain).

PATIENTS

Subjects appointed to 139 family doctors regularly using electronic clinical records (including doctors who were producing over 100 electronic prescriptions per week: 188,953 subjects and 334.088 prescriptions at the start, and 202,988 subjects and 335.198 prescriptions at the end of study).

INTERVENTION

(1) A software able to collect patients who had clinically important drug-drug interactions those that should be avoided (BOT I+II) was designed. (2) A report on these interactions was drawn up and delivered periodically to every single doctor, including patient identification and information on the drugs involved, possible consequences, and recommendations about what to do. (3) Clinical and educative sessions given by a trained pharmacist were carried out in doctors' health centre coinciding with their delivery.

RESULTS

Drug-drug interactions pre-intervention: prevalence 1.29%; by patient at risk 6.57%; by doctor 20.2. Post-intervention: prevalence 1.06% (improvement 17.6%, P<.000001), by patient at risk 5.17% (improvement 21.4%, P<.000001), by doctor 17.7 (improvement 12.1, P<.001).

CONCLUSIONS

Developing this technology leads to progress in patient safety, therefore it should be extended to all our family doctors. Other technologies such as an electronic alert when prescribing should be considered, particularly for either higher frequency or important consequences interactions.