Predicting the impact of a patient-directed financial incentive on choices of asthma controller inhalers in Australia: a discreet choice experiment and financial impact analysis

Problem

In Australia, despite subsidisation of medications via the national Pharmaceutical Benefits Scheme, out-of-pocket costs contribute to non-adherence with controller inhalers in people with asthma. For asthma, guidelines recommend that most patients should be prescribed regular low-dose inhaled corticosteroids (ICS-alone), but in Australia, most are treated with combination ICS/long-acting beta 2-agonists (LABA), which cost more to patients and government. This includes in patients with asthma of a severity where ICS-alone would be equally effective. This study sought to estimate the impact of a financial incentive in the form of a lower co-payment for ICS-only inhalers for people with asthma, on patient preferences for controller inhalers as well as the financial impact on Australian government drug expenditure.

Approach

Discrete Choice Experiment (DCE) using mixed multinomial models at varying levels of financial incentive. The setting was via an online survey of national representative cohort of adults and parents of children with asthma. Outcome Measures were demand for medicines (ICS, ICS/LABA, no controller) and related government pharmaceutical expenditure. Participants were adults (n=792) and parents of children (n=609) with asthma.

Findings

The co-payment attribute had a significant but overall small influence on controller medicine demand for both adults and parents of children with asthma (e.g. OR, 95%CI: adult concession 0.907 (0.890-0.923); Child, general beneficiary 0.957 (0.951-0.964)). Without changing the current co-payment, preference-based modelling predicted an increase in the use of asthma controlled medicines from 57% to 89%, with higher uptake of ICS-alone (29% current, 48% predicted) and reduced average cost per patient ($AUD38.54 c.f. $32.73). Reducing the co-payment on ICS-alone by 50% would increase its market share (43% to 50%) whilst completely removing co-payment would only have further marginal impact, but increase average cost of treatment ($AUD41.04 per patient).

Consequences

Though the DCE predicts some impact, introducing a new patient-directed financial incentive, as a stand-alone strategy, is unlikely to substantially improve the uptake of cost-effective controller medicines for asthma in Australia. Given the gatekeeper role of prescribers, usually general practitioners, on medication selection additional strategies directed at prescribers will be needed to change current practice.