As @Alexander already mentioned, you are looking for an approach that is called "individual participant/person/patient data meta-analysis" (IPD meta-analysis). He also refered to an article by Richard Riley, who has published a lot in this field. Please find below a collection of articles that I used for our advanced meta-analysis class:
Cooper, H., & Patall, E. A. (2009). The relative benefits of
meta-analysis conducted with individual participant data versus
aggregated data. Psychological methods, 14(2), 165–176.
Curran, P. J., & Hussong, A. M. (2009). Integrative data analysis:
the simultaneous analysis of multiple data sets. Psychological
methods, 14(2), 81–100. doi:10.1037/a0015914
Lyman, G. H., & Kuderer, N. M. (2005). The strengths and limitations
of meta-analyses based on aggregate data. BMC Medical Research
Methodology, 5(1), 14.
(already mentioned) Riley, R. D., Lambert, P. C., & Abo-Zaid, G.
(2010). Meta-analysis of individual participant data: rationale,
conduct, and reporting. BMJ, 340(feb05 1), c221-c221.
Riley, R. D., Lambert, P. C., Staessen, J. A., Wang, J., Gueyffier,
F., Thijs, L., & Boutitie, F. (2007). Meta-analysis of continuous
outcomes combining individual patient data and aggregate data.
Statistics in Medicine. doi:10.1002/sim.3165
Simmonds, M. C., Higgins, J. P., Stewart, L. A., Tierney, J. F.,
Clarke, M. J., & Thompson, S. G. (2005). Meta-analysis of individual
patient data from randomized trials: a review of methods used in
practice. Clinical Trials, 2(3), 209–217.
Stewart, L. A., & Tierney, J. F. (2002). To IPD or not to IPD?
Advantages and disadvantages of systematic reviews using individual
patient data. Evaluation and The Health Professions, 25(1), 76-97.