14 CHAPTER 1 Prescribing in older people Appropriate prescribing Although polypharmacy is an independent and important risk factor for drugrelated hospital admissions, the assumption that polypharmacy in itself is harmful to individual patients would be too simplistic. Indicated polypharmacy in multimorbid patients can also positively affect health outcomes, and withholding pharmacotherapy can have negative health consequences [31–33]. Underprescribing (i.e. the lack of an indicated drug without a valid reason for not prescribing it) is remarkably common in older people, especially in patients with polypharmacy [33–35]. For example, cardiovascular drug underuse in older patients has been associated with hospital admissions due to heart failure exacerbation [32,36]. Therefore, increasing ‘medication appropriateness’ is critical, not just reducing the number of drugs. Medication appropriateness is generally defined as the quality of prescribing pharmacotherapy related to the individual patient and refers to a continuous process of pharmacotherapeutic decision-making that maximises individual health gains [37,38]. The WHO six-step model is a validated method to promote appropriate prescribing (Figure 4) [39–41]. However, challenges in all steps of the prescribing process may be encountered in older patients with multimorbidity and polypharmacy compared to younger patients. For instance, the patient’s problem may be less obvious in multimorbid patients, and the misinterpretation of adverse drug reactions can lead to prescribing cascades (i.e. prescription of a subsequent drug to treat a drug-induced adverse event) . In addition, patient-specific therapeutic objectives may be different (e.g. life prolongation vs quality of life). Figure 4. WHO 6-step model of appropriate prescribing [39–41].