Important Design Principles have been identified for PCAS13. These Design Principles include the following:
Validity and Reliability
Validity and reliability are perhaps the most important yet misunderstood elements of the Design Principles. A Patient Classification/Acuity tool or measure is considered valid if it actually measures what it purports to measure, and in this case that means different levels or amounts of patient care that vary in the predicted direction.
For example, assume that a nursing unit is using a level 3 PCAS tool, with level 1 representing minimum care, level 2 indicating a moderate level of care, and a level 3 equals the maximum amount of care on a unit. If patient care is then studied and the results show that on average, patient care increases with each increase in patient care level, that result is direct evidence of validity. So if level 1 patients get less care than other level patients, and a level 2 patient gets more than a level 1 but less care overall than level 3 patients, the tool is valid because that the care varies in the predicted directions. Using a Patient Classification/Acuity tool that does not have established validity is unwise because of the lack of credible evidence that the tool actually works, even when staff are using it correctly. Using invalid PCAS measures will result in erroneous and incomplete estimates of actual patient care requirements, potentially affecting projected staffing levels and the resulting care quality. Validity should always be well established using sound research methods when a tool is first developed and periodically thereafter. The moral and scientific responsibility to create valid tools falls to the developing organization, whether an individual hospital, healthcare system, or private company offering the PCAS on the open market.
Reliability of a Patient Classification/Acuity tool means that if the measure is valid and being used correctly, the results of the ratings should be accurate and dependable. For example, if three different nurses who all know the care requirements of a particular patient separately rated his care needs using the same valid Patient Classification/Acuity tool, they should all choose the same indicators and end up with the same patient rating. When a tool is dependable and you can count on the ratings being correct, it is considered to be reliable.
It is also extremely important to understand the critical relationship between validity and reliability. A tool might start out with strong evidence of validity, but if it is used incorrectly, the ratings will become incorrect and thus unreliable. Unreliable ratings automatically render any PCAS tool invalid. This crucial relationship must be well understood from the start and form the basis for ongoing staff education and reliability and validity monitoring for PCAS tools and measures over time.
The importance of validity and reliability for PCAS tools cannot be overstated. In fact, it has been observed that Patient Classification/Acuity System measures have all too often lacked evidence of validity and reliability9,10,14,15. In order to assure that the PCAS tools used in healthcare are as sound as possible, the validity and reliability of these systems should be well established when it is initially developed and/or purchased, and the ongoing reliability of patient ratings should be assessed at least annually for every staff member rating patients with a given measure. In addition, a description of the research methods used to demonstrate validity and reliability should be provided and reviewed before implementation in a healthcare setting is seriously contemplated.
Simplicity and Efficiency
The need for simplicity and efficiency in a Patient Classification/Acuity System is critical to maintain overall system effectiveness and not add unnecessarily to nursing's workload. To that end is the scientific principle of parsimony, capturing the totality of care with as few indicators as possible, thereby achieving the gold standard of simplicity and elegance. Practically speaking, this means that more items or indicators on a tool are not necessarily better13. In fact, the Simplicity and Efficiency Design Principle can only be met by a PCAS tool "that is conceptually clear, concise, and time-efficient to use" 9,10 . Simplicity, efficiency, and the visibility of the tool and its indicators ultimately drive the overall usefulness of the measure.
PCAS measures that are embedded in the documentation systems of an electronic health record (EHR) are often in the background and not immediately visible to the nurse. As with any type of PCAS under consideration, it is critical that the nursing members of the system selection team see a total listing of the tool indicators, the associated weighting scheme, as well as a full description of the methodology so that they understand exactly how the care levels are calculated. Patient Classification/Acuity Systems should never be selected without this type of demonstration and level of understanding. This process will also assist in determining how much the system meets the Simplicity and Efficiency Design Principle.
Another important Design Principle to look for in a Patient Classification/Acuity System is that it should allow for ease in objective verification of tool ratings as well as the tool validation process13. This can be best achieved by having someone with both nursing and measurement expertise involved in the development of the measure.
It has been observed that the acceptability of PCAS measures is important to colleagues both inside and outside the nursing department. For members of the nursing team, acceptability is a function of how well the measure appears to capture the essence of nursing and patient care. This also implies the exercise of subjective nursing judgement in rating patient care needs13. When the Patient Classification/Acuity System is acceptable to nursing, acceptability in other critical departments such as Finance will occur as they are also educated about the system, how it can be used, the selection process and rationale, as well as ongoing system monitoring processes9,10. The importance of this step is crucial to any healthcare organization because of the important assertion that "valid and reliable PCAS's define and defend the work of professional nursing practice, protect patients from complications, and decrease the vulnerability of nurse staffing to budget cuts"17. As such, the care indicators on a PCAS tool must be visible and represent the full scope of nursing practice and patient care.
It is essential that when a Patient Classification/Acuity System is under development that a registered nurse with doctoral level expertise in measurement methods or an RN working directly with someone with that expertise has been involved throughout the tool development process. This helps assure that patient care and nursing's scope of practice are well understood and represented by the Patient Classification/Acuity measure. It also assures stronger validity and reliability of the PCAS tool at the start. In addition, access to registered nurse clinical experts for feedback and testing throughout the development process is also critical if the system is to appropriately define nursing care and meet the intent of this critical Design Principle.
This final Design Principle offered by Fasoli, Fincke, and Haddock13 is fundamental to a well-conceived, fully relevant Patient Classification/Acuity System for nursing. This principle involves the common knowledge and central belief that nursing work is much greater than the simple sum of individual tasks. Keeping this core knowledge and understanding of the interactive nature of nursing practice in mind and making sure it is incorporated throughout the system development, application, and utilization phase will help assure a system that works for nursing, the organization, and the patients it serves.