Healthcare costs of adverse drug reactions and potentially inappropriate prescribing in older adults: a population-based study

OBJECTIVES: To describe the distribution of costs based on potentially inappropriate prescribing (PIP) and adverse drug reaction (ADR) status in terms of total direct costs and costs caused by ADRs, among older adults. DESIGN: A retrospective cohort study was conducted among older adults, identified from a random sample of the general Swedish population. PIP was identified based on the Screening Tool of Older Persons’ Prescriptions (STOPP) criteria and ADRs were identified using the Howard criteria. Causality between PIP and ADRs was evaluated using Hallas’ criteria. Prevalence-based direct healthcare costs were calculated for the 3-month study period, including the total cost for healthcare and drugs, and the cost caused by ADRs. SETTING: All care levels, including primary care, other outpatient care and inpatient care. PARTICIPANTS: 813 adults ≥65 years. PRIMARY OUTCOME MEASURES: The prevalence and cost of PIP and ADRs. RESULTS: Total direct cost for persons with PIP was approximately twice the total cost of those without PIP (€1958 (€1428–€2616) vs €881 (€817–€1167), p=0.0020). The costs caused by ADRs was 10 times higher among persons with PIP, compared with those without PIP (€270 (€86–€545) vs €27 (€10–€61), p=0.047). For persons with ADRs caused by PIP, total direct costs were €4646 (€2617–€7931). This group represented 8% of the study population and used 25% of the costs. The main cost driver in all studied patient groups was healthcare contacts. CONCLUSIONS: Older persons with PIP and ADRs had high healthcare costs, particularly when ADRs were caused by PIP. Since these costs appear to be substantial, the potential savings by preventing their occurrence may, to a certain degree, cover the added cost of such activities. Further studies should be undertaken to provide further evidence on the costs of PIP, ADRs and ADRs caused by PIP.