EZ Rules from Westgard Quality Corporation is a computer program
for automatic selection of quality control (QC) rules that will
detect medically important errors. The idea of automatic QC selection
is that an appropriate level of QC should be selected for a given
situation, neither too little, nor too much.
The program is supplied on a floppy disk, and I observed uncomplicated
installation and performance on Windows ® 95, 98, NT and
2000 operating systems.
An interactive dialog forms the basis of program operation.
The user is prompted for input concerning method characteristics:
imprecision, bias, decision level, and expected rate of instability
(three level options) and number of control materials. The expected
rate of instability is used by the program to determine the necessary
power level for QC rules. Furthermore, the user chooses among
three principles for specification of quality requirement: (a)
an allowable total error (e.g., according to CLIA proficiency
testing criteria); (b) clinical (in the form of the decision
interval); or (c) related to biologic variation. The user further
selects among control rules on the basis of measurement of control
materials (so-called traditional rules) or on patient values
(average of normals principle). On the basis of this input, the
program suggests an appropriate control rule and number of control
measurements. As a supplement to the selected rule, an OPSpecs
chart may be viewed with an outline of performance for the selected
rule and a set of rules with related performance to the primarily
suggested one. Power curves are also presented for the displayed
rules for further orientation. Finally, a QC Validation Report
with input and calculated parameters, and graphics, is presented
that may also be printed.
The program can be used intuitively, and familiarization with
the program is aided by three tutorial examples. The manual contains
a "Getting Started" section that provides an easy introduction
and overview. Subsequent sections, "Learning Program Operation"
and "Rule Selection Methodology", give a more general
background with an outline of the selection procedure based on
the OPSpecs chart concept, partly as excerpts from earlier publications.
The final section "Technical Information", contains
definitions and computational methods. Tables, which also are
available in the online help menu, are provided concerning quality
demands (CLIA, clinical and biologic approaches). A listing of
the repertoire of control rules is available in the online help
menu. These include so-called traditional rules: Levey-Jenning,
Westgard multirules, mean and range rules (~70), and patient-based
rules (average of normals). Furthermore, extensive literature
references are provided; further information is available at
http://www.westgard.com
EZ rules represents the latest development of the QC Validator®
program series, which in the 2.0 version also provided the option
of automatic selection of QC rules. In the present program, the
interactive dialog facilitates the procedure and the average
of normals control rule principle is a new feature. Although
the main point of the program is automated rule selection, an
option for the user to evaluate the performance of a specific
rule might have been valuable, e.g., to compare a given rule
used commonly in a laboratory with the one suggested by the program.
This software, including its associated manual, is user-friendly,
provides appropriate instructions, performs well, and is available
at a reasonable price.
Kristian Linnet
Laboratory of Clinical Biochemistry
Psychiatric University Hospital
DK-8240 Risskov, Denmark