Lab Testing in the Outpatient Setting

What advice would you give to a patient or patient's family about protecting themselves from lab testing errors in the outpatient setting?

Respondent
Michael Astion, MD, PhD
Editor-in-Chief: Patient Safety Focus
Division Chief of Laboratory Medicine
Seattle Children's Hospital
Clinical Professor of Laboratory Medicine
University of Washington

Don't panic. My first advice to patients and their families is don't panic. Most lab test results provide useful information. Only rarely do lab test errors harm patients. Why? Bad news sells newspapers and the word spreads rapidly; good news about lab testing is normal and boring, so you don't read about it. A news story titled "Hemoglobin A1C testing used successfully to manage diabetes in tens of millions of patients" is unlikely to appear on the national news. Whereas a story titled "Lab mishap causes death of patient who received the wrong organs" will be picked up by many media outlets.

Minimize demands for testing. Do not demand testing or otherwise create an environment that supports over-testing, as over-testing increases the chances of a false-positive result and a false diagnosis (See Box). For severe illnesses, lab testing is essential. For example, diagnosis of HIV requires an HIV test. Troponin is essential for diagnosing myocardial infarction. But for ambulatory patients with common complaints, less (testing) is more. Googling symptoms and asking for an all-you-can-eat buffet of laboratory delights is not a good medical practice. Useful testing strategies for common ambulatory aches like backaches and headaches are rare. Patients often benefit from a conservative approach to testing even for common complaints like diarrhea and fatigue.

Know what tests are ordered and why. One of the more common errors related to lab testing is ordering the wrong test. Patients should discuss test orders with their doctors, keep a list of the tests ordered, and track results to reduce this type of error. For example, if the doctor states that she is going to order a free T4 test related to the patient's anxiety, rapid heart beat, and weight loss, but a free testosterone result comes back, then it's likely that she ordered the wrong test.

Follow pre-testing instructions. Following the doctor's pre-testing instructions increases the probability of an accurate test result. Snacks and meals of any kind can adversely affect fasting test results. For example, eating a pizza at midnight or feasting on a hearty breakfast the day of testing does not constitute fasting. Furthermore, stew is not a clear liquid, nor is chicken noodle soup.

Participate in the proper labeling of the specimen. Advise patients to check the label on the specimen containers to make sure they have the proper identifying information, including the proper spelling of the patient's name, date of birth, and whatever else should be on it, and then to compare it against the requisition if there is a manual requisition. Mislabeling errors occur relatively frequently. In a typical ambulatory setting, mislabeling rates occur at 2–4 per 1,000 collections, which, at a busy multispecialty clinic, could amount to more than one per week. Mislabeling errors can result in one patient receiving another patient's results. Furthermore, the risk of mislabeling increases for common names or names where the first and last names are interchangeable, such as William Peter or John Paul.

No news is not good news. Another common error committed by test providers is failing to retrieve test results, with rates ranging from 1–5%. This error is a significant source of patient harm, especially when failure to retrieve abnormal results leads to a delay in diagnosis. Unfortunately, there are still some doctors who tell patients to assume a test result is normal if the patient is not notified of the result. Patients who are not contacted about test results should call to retrieve them or retrieve them electronically if this service is available.

Collaborate to interpret test results. Test interpretation is often complex because it usually relies upon other clinical findings. Patients can make significant errors when trying to interpret their results, especially if they are unfamiliar with the test or it is new to them. Therefore, it is best to ask the physician for help. A reasonable rule of thumb for common tests is that patients should be more confident in a negative/normal result than a positive/abnormal result.

Usually, if a test result adequately explains the clinical findings, then testing is complete. If the test result does not match the clinical findings, then outpatients should consult their physician to determine if retesting on a new specimen is worthwhile.

REFERENCES

Epner P, Astion ML. Focusing on test ordering practices to cut diagnostic errors. Clin Lab News 2012;38(7):17-8.
Astion ML. Failure to report lab test results to outpatients. Clin Lab News 2009;35(10):18.
Astion ML. Advice to patients. Laboratory Errors and Patient Safety. 2006;3:11.

Attention Readers
Do you have additional or different advice for outpatients? Please send your suggestions to [email protected] and I will include them in a future issue of Patient Safety Focus.