Appropriate prescribing for older people

Abstract

Appropriate prescribing is the result of pharmacotherapeutic decision-making to maximise the net health benefit of treatment, given the resources available. Several risk factors for inappropriate prescribing in older people have been identified, such as polypharmacy, impaired renal function, and frequent transfers between healthcare settings. The objectives of the studies described in this thesis were to describe the frequency and nature of risk factors for inappropriate prescribing in older people, with a focus on polypharmacy, transitional care, and impaired renal function, and to develop and investigate interventions to improve appropriate prescribing. First, the Prescribing Optimization Method (POM) was investigated as a tool to improve appropriate prescribing. The POM consists of six questions plus checklists. The questions ask about adherence, undertreatment, overtreatment, adverse effects, interactions, and adjustment of dose, dose frequency, and/or formulation. General practitioners (GPs) applied the POM to case histories of patients on polypharmacy. Inappropriate prescribing occurred significantly less often when GPs used the POM: the proportion of correct treatment decisions increased by 13.4%, while the number of potentially harmful decisions decreased by almost 1 per patient. Then, the number of discrepancies found when the medication history at hospital admission was taken in the usual fashion and when it was taken using a structured history of medication use (SHIM) checklist was assessed. Discrepancies were found in 92% of patients. These results were confirmed by a study conducted in an old age psychiatry clinic. Next, the effect of a discharge medication intervention on the incidence and nature of post-discharge medication discrepancies was investigated. The intervention, consisting of patient counselling and a structured medication overview for the patient, GP, and community pharmacist (CP), did not affect the number of discrepancies. Although the number of discrepancies due to patient-related factors, such as unintentional continuation of discontinued medications, decreased significantly, the intervention had no influence on discrepancies due to system-related factors, such as dispensing errors. A subsequent study investigated whether changes to patients’ medication regimens at discharge were entered in the patient files held by GPs and CPs. The results showed that the intervention did not improve the incorporation of changes to the medication regimen into CPs’ and GPs’ patient files. Next, the prescribing consequences of renal impairment were examined. First, the best method for estimating renal function in older patients was investigated. The most widely used methods, Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease-Epidemiology (CKD-EPI) formulae were compared to one another. On average, all formulae slightly overestimated GFR with considerable individual overestimation or underestimation. Second, prescriber adherence to the Dutch dosing guideline for patients with renal impairment was investigated. Only 54% of patients were prescribed medications in compliance with the guideline. Thus, appropriate prescribing for older people depends on communication between patients, physicians, pharmacists, and other involved healthcareeproviders. It also depends on prescribers having sufficient knowledge of pharmacotherapy, which may be facilitated by the use of prescribing tools, such as the POM, and clinical decision support systems with dose adjust alerts for patients with impaired renal function.