MMSE model: Compared with best supportive care, the incremental costs were £1,174 for rivastigmine patches, and £1,336 for rivastigmine capsules. The QALYs gained were 0.1109 for rivastigmine patches, and 0.0882 for rivastigmine capsules.
The incremental cost-effectiveness ratio (ICER) was £10,579 per QALY gained or £158 per MMSE score gained with rivastigmine patches, and £15,154 per QALY gained or £226 per MMSE score gained with capsules. Compared with the capsules, the patches were associated with marginally more QALYs (0.0228) and slightly lower costs (a difference of −£162 over five years).
MMSE-ADL model: Compared with best supportive care, the incremental costs were £1,011 with rivastigmine patches and £1,213 with rivastigmine capsules. The QALYs gained were identical to those in the MMSE model.
The ICERs were £9,114 per QALY gained or £136 per MMSE score gained with rivastigmine patches, and £13,758 per QALY gained or £205 per MMSE score gained with capsules. Compared with capsules, the patches were associated with more QALYs and MMSE score gained, and slightly lower costs (a difference of −£202 over five years).
The main difference between the two models was more institutionalised days avoided with rivastigmine versus best supportive care in the MMSE-ADL model than in the MMSE model. The probabilistic sensitivity analysis showed that compared with best supportive care, the patches were cost-effective at a willingness-to-pay threshold of £20,000 per QALY in 100% of simulations and the capsules were in 89.7% of simulations (MMSE model).