Novius by the Numbers
Siemens Novius Lab® System
By Nancy Sivertson
Siemens Novius Lab® software utilizes a complex, highly functional numeric formatting
system for laboratory results. Formats are defined in Novius as four-digit entries with
a decimal point: AB.CD, where A is the minimum number of whole numbers, B is the maximum
number of whole digits, C is the minimum number of decimal places, and D is the maximum number
of decimal places. Acceptable ranges for each are from 0 to 16, but there is
a total length limit of 30. They are uniquely flexible, and display only significant
digits on patient reports. As an example: a numeric result defined by the entry
14.14 in the Numeric Format Rules has a minimum of 1 and a maximum of 4 digits to the left of
the decimal, and from 1 to 4 digits to the right of the decimal. More typically, the
number of decimal places is fixed, which would be represented by the formats 14.22 or 12.11.
Results entered for a given assay must match the result format specified
for that assay, and coordination of numeric formats in all members of a calculation is a
must.
Unit Testing of all results is vital in light of this numeric flexibility.
Each assay should be resulted at normal levels, and then at high and low borderline values for
every defined range to assure correct flagging and correct result display.
Calculation testing must include examples of results that test the limits of all the
variables in the group, as well as the limits of the calculated result. So, a
Cholesterol/HDL ratio should be tested with results that use the maximum and minimum digits
for Cholesterol, for HDL, and for the ratio, to assure consistent functionality.
If results for the variables in the equation are set up with more decimal places than the
calculation test, calculations can fail, because the result will not fit the numeric format
assigned to the calculation test. A good idea is to handle testing of all calculation
tests through a separate testing script which specifies testing steps for each calculation
test, which may work well with one set of results for the constituent tests, but fail to fire
with another set.
Normal - low - high, attention and critical QA value ranges are defined in the Test
Definition UDT. Defining them correctly requires a clear understanding of how the
rules work. Novius evaluates rules in sequence, first the normal values, then the
attention values, then the critical values. If the test passes the normal rule
(the result falls within the rule limits), no flag is written, the rule is
“passed”, and evaluation stops. If the test results are outside of rule
limits, it fails the rule, a flag is written, and the system moves on to evaluate next QA
rule. A result that fails multiple range rules would have multiple flags.
Typically, the Normal range exists within the boundaries of the Attention limits, which in
turn are within the boundaries of the critical range: (Cr Lo(Att Lo(Norm LO – Norm
Hi)Att Hi) Cr Hi). Errors are encountered when critical or attention values are
defined without consideration of the normal ranges in the system, since results are not
evaluated for these levels unless they fail the normal rule. For instance, if a normal range
is defined beginning at “0”, the attention and critical ranges cannot begin above
that point. For proper function, you cannot have a normal range of 0.0-0.5 and a
critical range of 1.0-10.0 (every normal result would fail the critical rule).
Any of the 3 levels can be ‘skipped’ by simply not defining limits for them,
and the evaluation of defined levels will continue as normal, with no flagging for the skipped
range type. For instance, with no Attention range established, the system would move directly
from the normal range evaluation to the critical range evaluation. If only the high
critical levels are to be flagged for an assay such as a drug level, the critical range can be
defined right down to zero on the low end, with the critical high limit at the other end: i.e. 0-200.
Delta ranges are established for specific assays to prompt the performing tech to check
results which change from one scheduled assay to the next. Delta limits are normally not
established for all assays, but for key elements in groups, such as Hemoglobin in the CBC and
Potassium in the metabolic profiles.
Technical limits, based on instrumentation and methodology are evaluated by the system
independent of the normal-critical cascade, so that results outside of the linear ranges of the
instrument will always be flagged. Numeric Result Translate Rules allow the
reported result to be converted to a “<x” or “>x” value when it
falls outside technical limits..
NOVIUS also offers an option to add a user-defined flag to results using Notification
Flag Definition. These flags are designed for laboratory use, and appear on the
TESTS screen viewable in the lab, but not on patient reports. They can be used to flag
any results which required action by lab staff, such as micro results which require outside
reporting, or results which qualify patients for internal studies or drug trials, or which may
be candidates for presentation. All assays with these notification flags can be included
on a daily management report created by the system for lab use.
If you would like to talk about other ways to help make your Siemens, Cerner or Eclipsys lab
upgrades and implementations easier, please feel free to contact me at
nsivertson@getvitalized.com
.