Assessing general practitioners' prescribing behaviour in elderly patients with concealed renal failure

Estimating renal function to reduce the risk of adverse drug reactions

The aging process is characterized by relevant changes in pharmacokinetics. Renal function is known to decline with aging. However, as a result of reduced muscle mass, older individuals frequently have a depressed glomerular filtration rate (GFR) despite normal serum creatinine, and such a concealed renal insufficiency may impact significantly on the clearance of hydrosoluble drugs, as well as the risk of adverse drug reactions (ADRs) from hydrosoluble drugs. The assessment of renal function should thus be a mandatory item in the global examination of patient characteristics. Equations for estimating GFR have become very popular in recent years. However, different equations may yield significantly different estimated glomerular filtration rate (eGFR) values, which have important implications in dosing drugs cleared by the kidney. Current knowledge suggests that eGFR based on the Chronic Kidney Disease-Epidemiological Collaboration (CKD-EPI) study equation outperformed eGFR based on the Modification of Diet in Renal Disease (MDRD) study equation and creatinine clearance estimate based on the Cockcroft-Gault formula as a predictor of ADRs from kidney cleared drugs. More recently, the combined creatinine-cystatin C equation was shown to perform better than equations based on either of these markers alone in diagnosing CKD, even in older patients. However, its accuracy in predicting ADRs and usefulness in drug dosing is still to be investigated.

How to improve drug dosing for patients with renal impairment in primary care - a cluster-randomized controlled trial

Background

Patients with chronic kidney disease (CKD) are at increased risk for inappropriate or potentially harmful prescribing. The aim of this study was to examine whether a multifaceted intervention including the use of a software programme for the estimation of creatinine clearance and recommendation of individual dosage requirements may improve correct dosage adjustment of relevant medications for patients with CKD in primary care.

Methods

A cluster-randomized controlled trial was conducted between January and December 2007 in small primary care practices in Germany. Practices were randomly allocated to intervention or control groups. In each practice, we included patients with known CKD and elderly patients (≥70 years) suffering from hypertension. The practices in the intervention group received interactive training and were provided a software programme to assist with individual dose adjustment. The control group performed usual care. Data were collected at baseline and at 6 months. The outcome measures, analyzed across individual patients, included prescriptions exceeding recommended maximum daily doses, with the primary outcome being prescriptions exceeding recommended standard daily doses by more than 30%.

Results

Data from 44 general practitioners and 404 patients are included. The intervention was effective in reducing prescriptions exceeding the maximum daily dose per patients, with a trend in reducing prescriptions exceeding the standard daily dose by more than 30%.

Conclusions

A multifaceted intervention including the use of a software program effectively reduced inappropriately high doses of renally excreted medications in patients with CKD in the setting of small primary care practices.

Trial registration

Current Controlled Trials ISRCTN02900734

Hospitalizations because of adverse drug reactions in elderly patients admitted through the emergency department: a prospective survey

BACKGROUND AND OBJECTIVES

Several studies have been conducted to determine the frequency and characteristics of adverse drug reactions (ADRs) in elderly populations, focusing on those leading to hospital admission. However, most of these studies have been limited in their ability to assess risk factors, particularly the renal status of patients. Thus, the aim of this prospective study was to assess the incidence of ADRs and associated factors leading to hospital admissions in the elderly population.

METHODS

All patients aged > or =65 years admitted to the Toulouse University Hospital through the Emergency Department during four non-consecutive weeks in 2002-3 were included in this study except for patients in ambulatory care or admitted for intentional overdoses. The characteristics of patients admitted for a suspected ADR were compared with those of patients admitted for other reasons.

RESULTS

The incidence of hospital admissions for ADRs was 8.37 per 100 admissions (95% CI 6.52, 10.52), corresponding to 66 patients with ADRs among 789 admissions. The most important factors associated with ADRs were the number of drugs being taken (odds ratio [OR] 1.18; 95% CI 1.08, 1.29), self-medication (OR 2.34; 95% CI 1.18, 4.66), use of antithrombotics (Anatomic Therapeutic and Chemical [ATC] classification B01; OR 2.26; 95% CI 1.33, 3.88) and use of antibacterial drugs (ATC J01; OR 4.04; 95% CI 1.50, 10.83). Surprisingly, exposure to drugs for acid-related disorders was associated with a low risk of ADRs (OR 0.26; 95% CI 0.09, 0.76).

CONCLUSION

A significant incidence of ADRs leading to hospital admissions was found among elderly people. Our study showed that there is a need to increase the availability of information for the general public concerning potential ADRs due to self-medication and for prescribers concerning ADRs due to drug-drug interactions and polypharmacy.