Running Rules in EDC – further commentary

4th November 2008 No Comments

Before returning with the 2nd part of the series – 4GL’s for eClinical, I just wanted to discuss further the execution of rules in EDC. Here is further commentary on the topic.

All EDC solutions offer a means to set rules that check data that has been entered. Typically, these rules would compare one or more values, against one or more other values, and, either based on a true results, or a false result log a query.  

The traditional CDM systems used to run what are called Consistency Checks on a batch basis – (aka Batch Checks).  This was efficient in that the database would run across all data executing the rules in a sweep – typically once per rule. For a database, this was quiet efficient. However, this was designed to run sometime after the data was recorded. For centralized data entry, where the staff entering the data are not the staff responding to the queries, this was fine. Double Data Entry is often used to capture the data entry errors.

EDC systems work on a different model.  The personnel entering data into the system are typically at the site. It makes sense that once the data is entered into the EDC tool, that the rules run immediately giving the operator the opportunity to make corrections immediately. 

The question is, when should these rules run?

  1. As soon as the data has been entered and the user leaves the field?
  2. As soon as the data is submitted to the database?
  3. Later, as part of batch checking?

Many opinions are held on this topic.  Let me tackle the first, and easiest one.

Batch Checking

Option 3 – run later as part of batch checking.  I don’t believe any person feels that running all rules on a batch basis for data entered at site makes sense.  I have heard it argued that ‘some’ rules should be on a batch basis.  The arguments for this have been a). for performance reasons and/or b). as all values are not available at the time the data is entered. I would respond to this argument by saying a). that a system should not have performance problems that would mean ‘any’ check cannot run during data entry. EDC systems should run even complex checks in < 100ms.  As to b). this is a design issue.  Most rules engines fire when all values are available, or, do not resolve to do anything if values are missing.  So - at least my opinion batch checking is largely superfluous.

Online Checking

Now – what about between the two online checking options?  At the field level, or on page submit?

Online Checking – Queries

If a user is recording data field by field, it can be distracting to see messages popping up repeatedly.  This is partly a question related to UI.  If the focus of the cursor is not adversely effected, this may be fine. Otherwise, it can be rather annoying. Some of you will be familiar with applications that ‘steal’ focus.  You think you are correctly keying information into an application only to find that the focus has been grabbed by a popup!  Very frustrating.  So – provided the focus is not impacted, producing queries, at least should be fine.  But what about other activities?  How about Dynamic CRF Pages?

Online Checking – Dynamics

It may make sense to insert a new field, or set of fields, based on a former response.  On paper, the content is fixed – it will say something like – If answered ‘Y’ then proceed to xxxx.  With an electronic medium, we have an opportunity to adjust the questions asked based on former responses. I believe dynamic forms only cause real problems for ‘Heads Down Data Entry’ staff [1].     With online EDC, heads down data entry is less common.  What is more typical is that the user reads the question, and completes a response.  If the next question changes, the impact is limited.  A common example – in a demographics form, subject is recorded as ‘Female’ – Dynamic adds a question such Is subject of child-bearing potential?

From a technical perspective, with web applications it is somewhat easier to handle a full page submit.  On an HTML based form, the actual data entry operates in the same fashion as an old paged style terminal (for those of us old enough to remember them!). The communication between the client (web browser) and the server only occurs when the user hits the save or submit button. 

Web 2.0 / Ajax

Web 2.0 technologies mean lots of things.  One feature though typical of these new application are that they are more interactive then traditional basic HTML paged apps. Ajax is a method now commonly used to create active response to data entry – an early example was used by google – Search-as-you-Type (SayT).  The technology provides the opportunity to capture data entered, and carry out an action immediately as a result – for google, that was to perform a search and present the results based on the term entered so far.   For EDC, this may result in some form of page dynamic such as the adding of a question, or block of questions.  From a browser independence perspective, Ajax doesn’t tend to cause problems as code is available for virtually all browsers. The majority of work is completed on the server side.

So – with web2.0 Ajax technologies, what else can we do with online rules execution?  

Well, we can take all the values entered into a CRF Page, compare the values with other values entered on other pages, and execute any action that is suitable for execution prior to data submit.  From eclinical_revolutn‘s comment, some vendors such as PhaseForward are already doing this.

We could go as far as submitting the data as the page is completed – as the user leaves field 1 and goes to field 2, Ajax is used to submit the value for field 1. The argument against this approach is that users must make a positive statement to submit data. I don’t concur with this.  In my mind, the positive statement is that the user has tabbed or cursor’ed out of the field.  The argument for the save as you go approach is that if a connection is lost, at least the data entered up to that point in time is saved. It is a training thing. If a user is trained that data is saved when you leave the field, then by leaving the field, they are confirming the save. A further argument against the save-as-you-go approach is that users are used to simply closing a browser, and the data entered, but not submitted is cancelled. Again, training and the removal of a Save or Submit button.  There are some challenges though – if the user completes information to the last field, and then closes the browser, should the last field value be saved?…

So – are EDC Vendors currently looking at new ways to interact with users using Web 2.0 technologies – I think so. Will we see user interfaces that match the interactivity that is offered by a thick client style rich UI – yes, but not until around 2010.

[1] Heads down data entry -an odd term  used to describe typically rapid keyboard data entry where the user does not look at the screen while keying – for example, a data entry clerk might be reading a paper CRF and entering the data into a CDM system.

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