Database lock

The Changing Role of Clinical Research Associates Patient Recruitment Reduced Time to Database Lock Management of Geographically Diverse Studies... 

The timeline should of course be as short as possible and it may be possible to conduct some studies in parallel or at least with a stagger rather than sequentially however, this must not be at the expense of the safety of the study subjects. Often there is no choice but to wait for the results of one study before starting the next. On the other hand, predefining the core data required for decision making, and making arrangements for rapid quality control and database lock, can substantially reduce the delays between studies. 

The definition of a per-protocol set of subjects allows us to get closer to the scientific question by including only those patients who comply with the protocol to a defined extent. The per-protocol set, like the full analysis set, must be prespecified in the protocol and then defined at the patient level at the blind review, following database lock, but before breaking the blind. It must be noted, however, that the per-protocol set is subject to bias and further, tends to overestimate the treatment effect. For this reason it is usually used only as a secondary analysis, supportive hopefully of the findings based on the full analysis set. 

There is one final opportunity to revisit the proposed methods of statistical analysis prior to the breaking of the blind, or in an unblinded trial, before the statistics group have seen study data. This so-called blind review usually takes place around the time of database lock and the following lists some of the aspects of analysis that would generally be considered ... 

The SAP will have detailed the precise methods of analysis and presentation and should ideally be finalised well before database lock. This enables work to begin in good time on the programming of the analyses. These programs will be tested on dirty data from the trial, so that they can be pretty much finalised before the trial ends, enabling, at least in theory, rapid turnaround of the key analyses. 

The ED plan will enumerate which studies are to be performed in healthy volunteers and which in patients. As the first studies progress, the information generated needs to be constantly evaluated while still blinded, and of course on unblinding after database lock at the end of each study. The decision to proceed to the patient population should take into account how well the studies have actually achieved their objectives. 

This event is one of the most visible in a study, representing the culmination of efforts spanning months or years and often representing the future of a product or even a company. Locking the database requires that every query and all outstanding discrepancies regarding data be resolved. 

There has been a push for direct data collection (DDC) as an alternative to remote data capture (RDC). In this approach most of the required clinical data are acquired directly from existing patient record systems such as MRI machines, ECG, EEG, TTM, laboratories, and other measurement equipment. This approach eliminates the need for paper transcription and reentry to another system. It promises error-free and resource-efficient data capture, which allows early locking of the database and therefore potentially earlier product launch [30]. 

Abdellatif et al. reported a method for data retention [56] in which collected electronic data forms of each participating site are saved on a read-only CD as PDF files after the site s database has been locked. SAS Output Delivery System (ODS), PROC Template, and PROC Forms were used to construct a read-only CD of the data forms in a PDF format for each site and then sent to the site s PI. 

With object-oriented databases, the interlinked object model is transparently carried over to persistence, and the developer is concerned with logical things—transaction boundaries, concurrency, how far to propagate locks—rather than mapping between two dissimilar models. 

Biometric security systems use biometric technology combined with some type of locking mechanism to control access to specific assets. In order to access an asset controlled by a biometric security system, an individual s biometric trait must be matched with an existing profile stored in a database. If there is a match between the two, the locking mechanism (which could be a physical lock, such as at a doorway an electronic lock, such as at a computer terminal or some other type of lock) is disengaged, and the individual is given access to the asset. 

The records/signatures linking using password/ID code-based signatures is either based on the use of software locks, on storing the electronic signature in a database table... 

Data enrichment needs access to external information sources that are not necessarily accessible from the system hosting the database or the web server. It needs update privileges on tables that are outside the core event tables. As such, it may need to be distributed, but not necessarily concurrent. In fact, our implementation locks data enrichment processes at the database level, to ensure that two installations of the application will not attempt the same enrichment procedure. Regarding performance, data enrichment can be delayed by data acquisition. 

Cook, J., M. Engel, P. Wylie, et al. 1999. Multiresidue screening of pesticides in foods using retention time locking, GC-AED, database search, and GC/MS identification. J. AOAC Int. 82 313-326. 

Frequently, RCTs are triple-blind, which means that neither the investigators, patients, nor sponsor has access to study results until the database is completed and locked. Oversight of the natural history RCT... 

Once all queries have been satisfied and the data have been entered, the database is locked. The final clinical/statistical study report can be written. 

Validation should ensure that the facility for locking/securing the database prevents unauthorized write access. The unlocking of a database should be strictly controlled by an SOP. 

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