Generally speaking, data analysis has to be tuned to the specific question and data you're interested in. What are you trying to do with this data? Would random numbers work just as well?
Also, I worry about the health-related question part - aggregating data sets of medical data is a serious business; it's not just a case of pooling it all together. If there is really a specific question of interest, either gather data from a valid meta-analysis (like a Cochrane review) or stick to a single sufficiently-large dataset so that you can understand the biases in the data collection.
