Objectives: To assess the relative cost-effectiveness of two therapeutic strategies: one starting with sacral neuromodulation (SNM) versus one starting with Botulinum toxin A (BTX-A) for the management of refractory incontinent idiopathic overactive bladder (OAB) patients, from the perspective of the Italian National Health Service (INHS).
Methods: Direct medical costs (<euro>2011) and benefits (quality-adjusted life years-QALYs) were assessed over a ten-year time frame adapting to the Italian practice a published Markov model. Clinical inputs were based on the published literature and on the expert opinion. Resource consumption rates were provided by clinical experts; unit costs were collected from a single hospital accounting and from standard tariff lists and public prices. Interventional procedures and management of adverse events were costed through a micro-costing approach. The primary outcome was incremental costs per QALYs gained (i.e. differential costs divided by differential benefits). Deterministic (DSA) and probabilistic (PSA) sensitivity analyses were conducted to assess the robustness of the model.
Results: Starting with SNM appears to be cost effective (i.e. under <euro>40.000/QALY) from year three (<euro>21,259/QALY) onwards and becomes dominant (i.e. more effective and less costly) at year ten: cumulative costs were <euro>32,975 for early SNM and <euro>33,309 for early BTX-A, while cumulative QALYs were 7.52 and 6.93, respectively. At year ten, DSA suggests the results robustness and 99.8 % of the PSA iterations fell within the cost-effectiveness threshold.
Conclusions: A therapeutic strategy starting with SNM may be considered cost effective in the midterm and cost saving in the long-term treatment of idiopathic OAB from the INHS perspective.