The reference group was women aged 70 to 74 years, who were admitted in good clinical condition less than four days after a subarachnoid haemorrhage and who had an anterior aneurysm of less than 10mm. In these women, aneurysm occlusion provided a gain of 0.29 QALYs at an additional cost of EUR 72, over conservative treatment, resulting in an incremental cost per QALY gained of EUR 247.
In almost all of the 191 other patient subgroups, the costs of occlusion were higher than those of conservative treatment. Occlusion was generally less effective than conservative treatment for patients who were admitted in a poor condition 10 days or more after haemorrhage. It provided minimal or no health benefits for patients over 80 years old who were admitted in poor condition four or more days after haemorrhage.
At a cost-effectiveness threshold of EUR 50,000 per QALY, occlusion was likely to be cost-effective for women aged 70 to 79 years and men aged 70 to 74 years who were admitted in good condition less than four days after haemorrhage. In women aged 70 to 74 years, who were admitted in good condition less than four days after onset, with a small posterior aneurysm, occlusion saved EUR 1,409 and gained 0.36 QALYs, making it dominant.
Occlusion was cost-effective in only seven of the 192 subgroups. Its cost-effectiveness was worse in patients with a large aneurysm than in those with a small aneurysm, and slightly better when the aneurysm was located in the posterior circulation than in the anterior circulation.
Influential inputs were the treatment costs for both strategies. Conservative treatment was mainly affected by the probabilities of poor or good outcome after re-bleeding and the risk of recurrent subarachnoid haemorrhage after treatment. Occlusion was sensitive to the probability of poor or good outcome after coiling. A lower discount rate improved the cost-effectiveness ratio for the reference group. Doubling the mortality from other causes led to a worse ratio.