Alternatively you can include this information on a data extraction form. In addition to Reference Manager, which can be used to handle bibliographic and document management functions, you have a number of options for managing the review process. RevMan, the Cochrane Collaboration's review management software, can be used to handle the results of individual studies and to integrate and synthesise the variables. Alternatively multipurpose databases such as SPSS or Access may be used to present cumulative data across a number of studies. If all the information you require is not available from an article you will have to try alternative sources.
Many articles are summaries of much larger reports of studies.
These are much more likely to have the information needed. Many organisations have data archives where fuller project details are deposited, indexed and archived. The extent of your efforts to pursue missing data depends on the nature and extent of missing variables. Generally, efforts to obtain items of data for articles that have met all other quality control criteria are more worthwhile than for articles that are of marginal benefit. Authors may still be contactable at the institutional address given in the article.