Douglas Noble on medication safety

douglas nobleA recent review of medication safety revealed a 9% error rate, of which 50% were significant and 2% potentially fatal. 

Just think of the significance of that for a moment, perhaps between amending drug charts – for every 500 drug orders written by a doctor, 1 patient could die as a result. 

In the larger world of patient safety, medication errors typically account for 30% of all adverse events and near misses.  In fact it could be argued that the recent patient safety movement took much of its momentum from the early work on medication errors by Bates et al. in the USA. 

Thankfully, the very serious errors, such as the delivery of intrathecal vincristine, become well known, but remain rare.  Human factors, culture, stress and lack of education all play a part in causality (at our medical school we had a one hour tutorial on how to prescribe after finals had been passed!?).  Yet, problems with drug charts are often one of the main root causes of error. 

Firstly, they’re just so tatty.  And then there’s the continual re-scribing with ever more important drugs slipping into oblivion with every re-write.  Despite many years of automated systems being available to correct errors and red flag potential interactions, the manual green pen is still relied upon to keep us right.  At the very least having the same drug card across the NHS would be a major protection for patients. 

Unsurprisingly many drug errors have complex accident trajectories.  The pharmacist’s green pen runs out of ink, the dispensing system is not fully understood, the little pink ones get remanufactured as oval white ones etc. In one of my own errors I prescribed warfarin as a regular medication instead of on the special part of the drug chart.  Due to lack of beds the patient was moved as an outlier onto a urology ward.  Haematuria began some days later and no-one thought twice about it – every one on the ward had that!  Eventually an INR – of some ghastly number and warranting a logarithmic scale – came back from the lab and a panic ensued.  A few doses of vitamin K later and all was well, but it could have been tragic. 

Often though it’s the smaller errors that cause the most serious damage and are sometimes not detected until years later: GP fails to get copy of discharge summary, out-patient appointment letter never arrives, amiodarone et al. becomes an unmonitored homely staple for years to come. 

Education at medical school and beyond is no doubt key.  Unfortunately in my own one hour tutorial it failed to teach me that Augmentin contained penicillin or that digoxin was prescribed in micrograms.  The harm was untold, although I’m still sure massive doses of digoxin could be beneficial in anaphylactic shock!

Douglas Noble has worked in surgery, emergency medicine, public health and for WHO Patient Safety. From 2006 to 2008 he was clinical adviser to chief medical officer for England, Sir Liam Donaldson.