Multimorbidity or polypharmacy: two sides of the same coin?

Polypharmacy, broadly defined as the chronic co-prescription of several drugs [1], has long been recognized as problematic. The greater the number of medicines a patient takes, the greater the risk of adverse effects of any one medicine, and the greater the risk of drug?drug interactions. Thus, polypharmacy is an accepted risk for poor health outcomes, including hospitalizations and mortality [2]. The number of drugs per patient (or polypharmacy) has come to be used as a measure of potentially hazardous professional behaviour, and is sometimes used in conjunction with the term ‘inappropriate prescribing’. Nonetheless, the prevalence of polypharmacy is rising inexorably [3]. This rise is driven, principally, by the rising prevalence of multimorbidity, i.e. the co-occurrence of two or more chronic long-term diseases or conditions in one patient [4]. The issue is compounded by clinical guidelines that advocate the use of several medicines in the management of individual diseases and their associated risk factors [5]. The result is a dilemma for prescribers: on the one hand there is the need to keep the number of medicines to a minimum, while on the other ensuring that the patient receives what evidence-based guidelines advocate as being in their best interest [6].