In scenarios where the stability of the quality control (QC) material is limited to a specific timeframe, such as 21 days in the case of hematology, you can still perform trend analysis within that time frame. Here’s how you might approach trend analysis for hematology QC using a hypothetical example:
Example: Hematology QC for Complete Blood Count (CBC)
Assumptions:
- Hematology QC material is stable for 21 days.
- You have data for daily QC results for a specific parameter, let’s say Hemoglobin (Hb), over these 21 days.
Steps:
- Data Collection:
- Collect daily QC results for Hemoglobin (Hb) testing over the 21-day period
- Record the QC values for each day.
- Calculate Moving Range (MR):
- Calculate the moving range (MR) for each set of consecutive days.
- MR1: |Hb_Day2 – Hb_Day1|
- MR2: |Hb_Day3 – Hb_Day2|
- And so on…
- Calculate Average MR:
Calculate the average moving range over the 21-day period:
Average MR = (MR1 + MR2 + … + MR20) / 20
- Initial Acceptance Range:
Set an initial acceptance range as 3 times the average MR.
- Control Chart:
- Plot the Hemoglobin QC values on a control chart over the 21 days.
- Add the upper and lower control limits based on the initial acceptance range.
- Trend Analysis:
- Observe the Hemoglobin QC values’ trends on the control chart within the 21-day period.
- Monitor for any QC values falling outside the control limits or showing consistent upward/downward trends.
- Update Acceptance Range:
- As you observe trends within the 21-day period, you might adjust the acceptance range if needed
Example Plot:
In this scenario, you’re analyzing the trend of Hemoglobin QC values over a 21-day period using moving ranges and control charts. The key is to observe any patterns, shifts, or trends within the defined timeframe and adjust the acceptance range based on your observations.
Remember that the stability of the QC material for 21 days is a constraint, and your analysis will be limited to that timeframe. Regular review and adjustment of the control limits within this timeframe will help ensure the quality of your hematology testing process
About the author
Dr. Sambhu Chakraborty is a distinguished consultant in quality accreditation for laboratories and hospitals. With a leadership portfolio that includes directorial roles in two laboratory organizations and a consulting firm, as well as chairmanship in a prominent laboratory organization, Dr. Chakraborty is a respected voice in the field. For further engagement or inquiries, Dr. Chakraborty can be contacted through email at director@iaqmconsultants.com and info@sambhuchakraborty.com. Additional resourcesand contact information are available on his websites, https://www.quality-pathshala.com and https://www.sambhuchakraborty.com, or via WhatsApp at +919830051583