Here's a study from two academic medical centers in Philadelphia. The authors looked at the effect of a nearly hard CPOE stop of concurrent orders for warfarin and trimethoprim-sulfamethoxazole, versus the old fashioned method of having the pharmacist call to express concern when such an order was entered:
Results The proportion of desired responses (ie, not reordering the alert-triggering drug within 10 minutes of firing) was 57.2% (111 of 194 hard stop alerts) in the intervention group and 13.5% (20 of 148) in the control group (adjusted odds ratio, 0.12; 95% confidence interval, 0.045-0.33).
...the study was terminated early because of 4 unintended consequences identified among patients in the intervention group: a delay of treatment with trimethoprim-sulfamethoxazole in 2 patients and a delay of treatment with warfarin in another 2 patients.
One instance was a delay of 3 days in starting the antibiotic (which had been recommended by the ID service!). In looking at the body of the paper, the other instance of antibiotic delay was actually a failure to start the antibiotic at all. Of the warfarin delays, one was a one day delay and the other was a three day.
The study didn't evaluate outcomes.
The boosters of CPOE as a facilitator of patient safety have been driven more by a belief system than evidence. Meanwhile, this year there have been several papers showing negative consequences. This may make my year end top ten list.
More from Med Page Today.
By the way, there's no absolute contraindication to prescribing warfarin and trimethoprim-sulfa together, provided you can monitor the INR frequently, which is easily done in hospitalized patients.