I have 10 studies who look at a surgery for facial paralysis. The main outcome is time to nerve recovery. I have the mean, SDs for the time in months to recovery but obviously there is no control or baseline data. Do I just use zero for the mean and SD for my pre-op values? This gives me a weighted average which is essentially what Im looking for, but want to make sure I present the date the correct way.
I see no reason why you could not use a meta-analytic approach when attempting to identify overall recovery time as you describe. See this article for a similar conceptual example. The authors examine mean weight loss in this instance - but the idea is similar in that it is a meta-analysis based on a single value that represents change over time. In your instance, it would be mean recovery time (however that is defined) instead of the mean change in weight. Additionally, based on your description there is no need for what you describe as pre-op values.
I hope that helps.