The Longitudinal Idiopathic Intracranial Hypertension Trial: Outcomes From Months 6–12

Purpose To determine whether the beneficial effects of acetazolamide (ACZ) in improving vision at 6 months continues to month 12 in participants of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT). Design Nonrandomized clinical study. Methods In the IIHTT, subjects were randomly assigned to placebo-plus-diet or maximally tolerated dosage of acetazolamide-plus-diet. At 6 months subjects transitioned from study drug to ACZ. This resulted in the following groups: (1) ACZ to ACZ; n = 34; (2) placebo to ACZ; n = 35; (3) ACZ to no treatment; n = 16; and (4) placebo to no treatment; n = 11. Ninety-six IIHTT subjects had evaluations at 6 and 12 months. Our main outcome measure was change from month 6 to month 12 in visual field mean deviation (MD) with secondary measures being change in papilledema grade, ETDRS scores, and quality-of-life (QoL) measures. Results The ACZ to ACZ group improved 0.35 dB, P = 05; placebo subjects with no ACZ improved 0.81 dB MD, P = 07 at 12 months. The other groups improved 0.35–0.46 dB MD. Mean improvements in papilledema grade occurred most markedly in the group that exchanged placebo for ACZ (0.91 units, P < 001). QoL and headache disability scores showed significant improvements in the placebo group with added ACZ. Conclusion Improvements in MD continued from month 6 to month 12 of the IIHTT in all treatment groups, most marked in the placebo group tapered off study drug. Adding ACZ to the placebo group significantly improved papilledema grade, headache, and QoL measures.