Establishing Units of Measure

For each lab test Question you must define each unit of measure acceptable for that Question, and how to convert Lab Units to a preferred unit. The following steps are required:

• Defining Lab Units
  
• Defining lab test Question Units
  
• Defining Unit Conversions
  
• Defining Preferred Conversion Groups
  

Defining Lab Units

You must define all acceptable units of measure for all lab test Questions in the Maintain Lab Units window.

If you collect data using different units whose value is exactly the same (for example, percentages and decimal values), you can group those units into synonym groups by giving them the same Representative Unit Code. To do this, you must define a unit with the same name you want to use as the Representative Unit Code. This Code must not be longer than ten characters, and should be meaningful because it is what you will see in other Oracle Clinical lab definition windows. When you save this unit definition, its value becomes available to other units in the Representative Unit Code field list of values.

You have the option of adding free form text to help in pronunciation. Lab unit pronunciation appears only on this form and on the Lab Units Report.

You must define Lab Units at the Global Library location. You can add a new unit at any time. You can change a unit only if it has not yet been saved, and delete one only if it is not referenced by a lab test Question, but you can choose to make a unit inactive at any time.

To define Lab Units:

1. Navigate to Labs, Lab Units, and then Lab Units. The Maintain Lab Units window opens.
2. In the Lab Unit Code field, define the name of the Lab Unit. For example, g/ml.
3. In the Lab Unit Name field, enter a descriptive name for the Lab Unit.
4. Enter a Representative Lab Unit Code. These codes enable you to define Lab Units as equivalent in the system. For example, because the Lab Units mg/ml and mg/cc are equivalent, you can define mg/ml as their common Representative Lab Unit Code. You can enter a code of up to 40 characters.
5. (Optional) Describe how this Lab Unit is pronounced in the Lab Unit Pronunciation field.
6. Select the Active? box to enable this Lab Unit to be used, or clear it to hide it from the system.
7. Save. Oracle Clinical commits this Lab Unit to the database.

Defining lab test Question Units

When you have defined all necessary Lab Test Units, associate each lab test Question you will be using with as many units of measure as apply, but at least one.

Lab units can be selected only by their representative Lab Unit code; however this code represents all the synonyms in the group—that is, all synonyms in the group are valid for the lab test Question.

In the Maintain lab test Question Units window you can insert representative Lab Units and delete those not referenced from Lab Unit conversions, ranges, Preferred Copy Groups, or preferred conversion groups. If the Lab Unit is referenced, you can choose to make it inactive. The Active? field controls whether the Lab Unit appears on lists throughout the Lab Ranges subsystem when Lab Units are called for. If a unit is marked inactive, it does not appear on lists.

To define lab test Question units:

1. Navigate to Labs, Lab Units, and LTQ Units. The Maintain lab test Question Units window opens.
2. Query for the lab test Question to which you want to associate units.
3. Define each representative Lab Unit name that you want to use as a unit measure for this Question, and either select the Active? box to enable this Lab Test Unit for the Question or clear it to render this unit inactive for this Question.
4. Save. Oracle Clinical enables you to use the representative Lab Test Unit or Units when you enter lab data for this Question.

Defining Unit Conversions

You must define a unit conversion for each Question that has more than one acceptable unit of measure. You can write a Derivation Procedure that references this conversion formula (see Validation and Derivation Procedures).

If your study collects lab data for the same Question in multiple unit types (for example, kilos in Europe and pounds in the U.S.), you can specify conversion formulas to ensure that the data can be analyzed and reported using a single unit of measure. Use the Lab Unit Conversions window to set up standard conversion definitions.

The Lab Unit conversion must be unique in both source (the From: Lab Unit Name) and destination (the To: Lab Unit Name); the system checks for uniqueness when you leave the Lab Unit conversion record.

Always specify the conversion TO your preferred unit of measure, the one you will use to analyze the data. Later, in the Maintain Preferred Conversion Groups window (referenced in Defining Preferred Conversion Groups), you specify which unit is preferred for each Question.

The conversion must be expressed in terms of multiplication and/or addition. To divide, multiply by a fraction; to subtract, add a negative number. However, you cannot enter a multiplier of zero or a negative number; doing this results in an error message. The system issues warning messages in the following circumstances:

• The inverse of the reverse multiplier is not within 1/10000 of the new multiplier.

• Another multiplier for the same lab test Question is within 1/10000 of the new one.

To define a Lab Unit conversion:

1. Navigate to Labs, Lab Units, and LU Conversions. The Maintain Lab Unit Conversions window opens.
2. Query for the lab test Question for which you want to define conversions.
3. Query for a Lab Test Unit you want to use as the From value. You can only choose Lab Test Units that have been defined for this Question in the Maintain lab test Question Units window (referenced in Defining Preferred Conversion Groups).
4. Query for the Lab Test Unit you want to use as the To value. In addition to being defined as a Lab Test Unit for this Question, you must also choose a different unit than you selected as the From value.
5. Choose a Conversion Source.
6. Enter the Multiply Number and/or Add Number for this unit conversion.
7. (Optional) Enter a comment that describes this conversion further.
8. Save. Oracle Clinical saves this Lab Unit conversion for this Question.

For more information, see:

• Testing a Lab Conversion Calculation
  

Testing a Lab Conversion Calculation

Once you have completed the required fields and saved the definition, you can click the Test Conversion button to try it out.

Defining Preferred Conversion Groups

A preferred conversion group is a set of lab test Questions and the preferred Lab Unit of measure for each Question. The preferred conversion group, together with the relevant Lab Unit conversion formulas, can be used by a Derivation Procedure to convert a response to the lab test Question collected in one unit of measure to a derived value in the preferred standard unit of measure (see Validation and Derivation Procedures).

1. Navigate to Labs, Lab Units, and Pref Conv Groups. The Maintain Preferred Conversion Groups window opens.

2. Define the unique group ID in the Group field. This ID can be up to 10 characters long, and you cannot change it once you save the group.

3. Define a Group Name.

4. (Optional) Enter a comment to describe supplementary information about this preferred conversion group.

5. Enter each Preferred Lab Unit for this group:

   1. Query for a lab test Question. When you choose one, Oracle Clinical populates its domain as well.

   2. Query for a Lab Unit Name associated with that Question.

   3. Enter the number of decimal places that you want reports displaying this value to use. Once you save, you cannot change this value.

   4. (Optional) Enter a comment with supplementary information about using this preferred Lab Unit for this group.

6. Save. Oracle Clinical commits this preferred conversion group to the database.