Author response: Fascial closure in IPOM repair: the case for long-term follow-up and clinical transparency

We agree indeed that long-term follow-up is essential in studies such as the PROSECO trial.1 Therefore, we are currently collecting 3- and 5-year follow-up data including a clinical visit at 3 years and completing of the Ventral Hernia Pain Questionnaire (VHPQ) at 3 and 5 years. We fully acknowledge that a key challenge in long-term clinical trials remains the risk of an increasing number of patients lost to follow-up, which could potentially hamper the final analysis. We will therefore perform a detailed analysis of all reoperated patients, including the cause of reoperation.

Dr Wang suggests that the double-blind design might raise practical and ethical concerns. In our experience, there are several ways to conduct trials with a double-blind design without causing such drawbacks. In the PROSECO trial, blinding was routinely discontinued after the 1-year follow-up, as stipulated in the original protocol. With this limitation of the length of the period with reduced transparency, we feel confident that there should not be any major negative impact on the continuity of care.

Moreover, we cannot see that the blinding procedure should be associated with any ethical concerns as this was clearly explained to the patients before they gave their informed consent to participate. If the clinical situation so required, or if the patients opted information on group allocation at any time, the envelopes containing information on group allocation were opened without delay.

Single-blinding by outcome assessors or the use of an independent endpoint adjudication committee might be interesting alternatives as suggested by Dr Wang. In the referred study by Van der Ende et al. the added value of a blinded outcome adjudication committee was limited in a stroke trial using a Prospective Randomized Open Blinded End-point (PROBE) design. This conclusion was based on the fact that the trial applied standardized, algorithm-based outcome assessment by a central assessor who was unaware but not formally blinded to treatment allocation. We seriously doubt that this observation will hold true in a hernia trial where assessors perform a clinical examination of the abdomen.

In summary, we fully agree with Dr Wang that long-term follow-up is essential in clinical trials. However, we cannot see that the double-blinding design is associated with any major risk of inducing practical or ethical concerns and we therefore propose that this should still be considered the gold standard procedure in randomized clinical trials.