Research studies find that American doctors make errors in writing prescriptions at rates of 5 to 81 percent. Most errors in prescribing medications are caught at the pharmacy, but a shocking number of drug prescribe in error find their way to patients.
Errors in writing prescriptions are surprisingly common. A study published in the Medical Journal of the Armed Forces of India in 2014 found an astonishing 1,012 errors in just 1,000 prescriptions. Studies of prescribing errors in the United States have found that doctors make mistakes from 5 to 81 percent of the time. For centuries, doctors whose prescriptions were incorrectly filled could blame the pharmacist's inability to read their handwriting. However, even with the advent of electronic prescriptions, prescribing errors continue.
Software glitches and system design errors very seldom cause prescription errors, but that isn't to say that e-prescription systems are easy to use. It can become cumbersome to enter patient data into the prescribing system. Sometimes the wrong patient's data are attached to a prescription. Sometimes the prescriber simply selects the wrong option. Sometimes the doctor is simply tired.
A study of prescription errors in the United States found that problems that end in the patient's getting the wrong drug fall into predictable categories:
- 11 percent of errors involve the wrong dose.
- 19 percent of errors involve the wrong dosing instructions.
- 21 percent of errors involve the wrong duration of therapy.
- 40 percent of errors involve the wrong drug quantity (for example, telling the pharmacist to dispense 60 tablets when the instructions say to take one tablet a day for 30 days).
There are some analysts who conclude that problems with electronic prescriptions outweigh their advantages. Here are seven examples of the sorts of problems you as a patient might encounter as a result of electronic prescription error.
1. Wrong drug selected from a pull-down menu
Seven-year-old Timmy was taken to the doctor with a strep throat. The doctor took a swab of Timmy's tonsils and ran a culture, determining that the boy had an infection with a type A Streptococcus. The prescription for treating this kind of strep throat is usually penicillin, but the doctor was tired and clicked on penicillamine, a medication used to treat rheumatoid arthritis, kidney stones, and Wilson's disease, a condition that causes an overloading of copper in the liver. The pharmacist did not question the prescription and Timmy was given the drug. After a couple of days, Timmy's sore throat was not any better, and he was complaining of nausea and constantly having to go to the bathroom with severe diarrhea. Timmy's parents took his to the emergency room, showed the ER doctors all of his prescriptions, and the error was caught. Timmy rapidly improved once he was given the right medication.
Many electronic prescription systems have pull down menus of look-alike, sound-alike medications. A doctor intending to give a patient Ranexa for angina, for example, is offered an opportunity to prescribe PreNexa, which is a nutritional supplement used during pregnancy. This kind of error is very distressing when the patient is a man.
2. Choosing the wrong formulation
Many medications come in an extended-release formula. The dosage of the medication is different when an extended-release version is prescribed.
A common error involves the prescription of valproic acid, which is marketed in the United States as Depakote. The manufacturers of the drug offer it as delayed-release capsules (Depakote Sprinkles), delayed-release tablets (Depakote), and extended-release tablets (Depakote ER).
A doctor intended to give her patient a 1000 mg dose of extended-release Depakote ER, but clicked on the pull down menu to prescribe 1000 mg of delayed-release Depakote. Ten hours later the full dose of the medicine was in the patient's bloodstream, with predictable side effects: extremely low blood pressure and severe sedation. Fortunately, the patient recovered.
In the United States, different pharmaceutical companies define "extended release" in different ways for different medications. The extended-release period may be 12 hours, or 24 hours, and the medication may be enteric coated (treated so it dissolves in the small intestine, not in the stomach), or not, with major consequences in patient care.
Another medication that is subject to serious prescribing errors is insulin. Some longer-lasting insulins such as Lantus are taken every 12 hours. Other longer-lasting insulins such as Toujeo are only taken once every 24 hours.
Five More Common Prescription Errors
Choosing the wrong medication entirely or the wrong form of the medication aren't the only ways clinicians can go wrong using e-prescription systems. Here are five more potential problem errors.
3. Missing Overdose Alerts
A middle-aged man with a seizure disorder was admitted to the hospital in status epilepticus, seizures that simply would not stop. The doctors successfully treated his condition with high-doses of anticonvulsant drugs, and after a few days started giving him 1500 mg of a medication called Dilantin (phenytoin sodium). When the man was finally ready to go home, his hospitalist gave him a prescription to continue the 1500 mg of Dilantin daily, instead of a more appropriate dosage of 500 mg a day. Both the doctor and the pharmacist ignored a pop screen that warned "EXCESSIVE DAILY DOSAGE." A few days later, the man was readmitted to the ER, unable to wake up. He was diagnosed as suffering Dilantin toxicity.
Most doctors don't like the alert system in most electronic prescription systems. Pop-up screens warn of allergies, duplicates, potential drug/drug interactions, and inappropriate doses, but the same pop-up screen may appear several times as the prescription is being made. The doctor (or the nurse practitioner) may have to enter the same reason for overriding the warning several times during the process of filling out the prescription. Electronic prescription systems can cause doctors and other prescribers to become desensitized to warnings, and actually increase serious prescription errors.
4. Failure to Adjust Dosage
The sixty-year-old man who is writing this article was admitted to the hospital with sepsis from an infection in a cut on big toe. The Proteus and Klebsiella bacteria that were making him very sick were beginning to spread through his body, and he was put on an IV antibiotic called vancomycin. This potent antibiotic knocks out many kinds of infection, but it also puts severe stress on the kidneys. The effects of the antibiotic on the kidneys are recognized by increasing levels of a protein in the blood called creatinine.
When the patient started the medication, his creatinine levels were zero. Twenty-four hours later they were 0.8, which is still normal. Another twenty-four hours later his creatinine levels were 2.0, which was a sign it was time to look at treatment with other antibiotics to avoid kidney damage. Fortunately for the writer of this article, his doctors adjusted dosage before kidney damage occurred. Some patients on vancomycin have had to go on renal dialysis when they got too much of the drug.
Adjusting medications is especially important for people who have kidney disease, and for the elderly. The most common problem medications are gliptins, metforming, perindopril, fenofibrate, glibenclamide, olmesartan, bisphosphonates, and strontium. It's not a bad idea to ask the doctor about dosage when receiving any of these medications.
5. Interruptions While on the Phone
About one in three US physicians uses a smart phone to send prescriptions to the pharmacy. Interruptions in the process (such as a personal phone call or a personal text) can lead to prescribing errors.
A hematologist was using his iPhone to call in a prescription for a patient who was going to have heart surgery. For the next week, the patient was to receive an unusually high dose of an anticoagulant, 300 mg a day of Plavix (clopidogrel). A text from his housekeeper about a kitchen fire came in while he was sending in the prescription, however, and he forgot to note that the high dosage Plavix was to be discontinued after the surgery. Two weeks later the doctor received word that his patient had had successful surgery, but had died of bleeding in the pericardium that had caused cardiac tamponade, essentially choking off circulation.
6. Errors In, Errors Out
A baby was brought to the doctor's office for treatment of what turned out to be an E. coli infection causing diarrhea. When the child was brought in, the nurse noted her weight as 20 kilos, although her weight was actually 20 pounds. The doctor wrote out a prescription for the antibiotic in a dosage as if the child weighed nearly twice as much as she did. The antibiotic made the diarrhea even worse, and the prescription was only changed when the baby's mother noticed the error on the discharge paperwork.
Even in the United States, body weight is noted in kilograms, not in pounds. Dosages are computed on the basis of the metric system.
Another common error is failure to note pregnancy. Entire classes of drugs are safe except for pregnant women.
7. Ambiguous Abbreviations
Doctors who get in a hurry can leave out leading zeros (the zero in front of the decimal point that indicates that the dosage is less than one unit) or trailing zeros (the zero that indicates the precision to which the dosage is to be measured). For instance, in a handwritten prescription, a dosage of .4 mg might be misread as 4 mg, ten times too much.
- Clinical prescriptions can be especially confusing. In one case, "Dilaudid 0.6 mg Q 10′ PRN (every 10 minutes as needed) was misinterpreted as "Dilaudid 0.6 mg QID PRN (4 times daily as needed)."
- Using the abbreviation "pot" for potassium instead of the chemical symbol "K" (as in a prescription for potassium chloride) can lead to do oddly dispensed prescriptions in states where marijuana is legal.
- The symbol MgSO4 actually stands for a common laxative, magnesium sulfate, although some doctors use it for morphine, morphine sulfate.
- The commonly used prescriptions µg, OU, and D/C need to be written as "mcg," "both eyes," and "discharge" (or "discontinue"), respectively.
Even worse are prescription errors caused by confusing patients, or by failing to discontinue prescriptions that are no longer needed. Protect yourself by letting your doctor know immediately when you experience serious side effects and whenever possible choose doctors whose offices display relaxed efficiency.
- Mohan P, Sharma AK, Panwar SS. Identification and quantification of prescription errors. Med J Armed Forces India. 2014 Apr
- 70(2):149-53. doi: 10.1016/j.mjafi.2014.01.002. Epub 2014 Apr 3. PMID: 24843204.
- Odukoya OK, Stone JA, Chui MA. E-prescribing errors in community pharmacies: exploring consequences and contributing factors. Int J Med Inform. 2014
- 83:427-437.
- Photo courtesy of Charles Williams: https://www.flickr.com/photos/charlesonflickr/3926259585
- Photo courtesy of Open Source Way: www.flickr.com/photos/opensourceway/7496802140
- http://www.cnn.com/2015/09/22/health/doctor-diagnostic-error-iom-study/ http://lifeinthefastlane.com/doctor-exposed-error/