Added value of this study
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ADVERSE EVENTS
This study provides a prospective detailed follow-up (range 2–8.5 years) of the long-term efficacy and safety of ONS in patients with MICCH who had participated in the only randomized, dose-controlled study of the effects of ONS in MICCH to date (ICON trial). Both participants who had improved at the end of the randomised trial and those who had not improved were included in the follow-up, providing important information on whether early improvement persisted and whether delayed improvement could occur with continued treatment. Moreover, compared to existing studies, this study had minimal selection bias, a long specified baseline of 3 months, full evaluation of outcome and adverse events at regular half-yearly intervals up to 8.5 years, and detailed information on the number of participants who were lost to follow up and why.The mean follow-up was 4.2 ± 2.2 years for a total of 370 person-years. Objective and subjective sustained efficacy were high. More than two-third of the ≥50% responders at the end of the ICON study retained this response. Moreover, during the follow-up period, more than one-third of the non-responders converted to a ≥50% responder for at least half the follow-up period. At the last follow-up, subjective improvement from baseline was reported by 78% of the participants and 81% would recommend ONS to other patients with MICCH. Hardware-related serious adverse events (SAE; formally defined as “serious” solely because short hospitalisations were required for replacements) occurred in 55% of participants with a SAE rate of 0.37 person-year.