, Volume 27, Issue 11, pp 1521-1527
Date: 20 Jul 2012

They Don’t Know What They Don’t Know: Internal Medicine Residents’ Knowledge and Confidence in Urine Drug Test Interpretation for Patients with Chronic Pain

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Urine drug testing (UDT) can help identify misuse or diversion of opioid medications among patients with chronic pain. However, misinterpreting results can lead to false reassurance or erroneous conclusions about drug use.


To examine the relationship between resident physicians’ knowledge about UDT interpretation and confidence in their ability to interpret UDT results.


Cross-sectional survey.


Internal medicine residents in a university health system in the Bronx, from 2010 to 2011.


We assessed knowledge using a 7-item scale (UDT knowledge score), and confidence in UDT interpretation using a single statement (“I feel confident in my ability to interpret the results of urine drug tests”). We conducted chi-square tests, t-tests, and logistic regression to determine the association between knowledge and confidence, and in exploratory analyses to examine whether resident characteristics (gender, training level, and UDT use) moderated the relationship between knowledge and confidence.


Among 99 residents, the mean UDT knowledge score was 3.0 out of 7 (SD 1.2). Although 55 (56 %) of residents felt confident in their ability to interpret UDT results, 40 (73 %) of confident residents had a knowledge score of 3 or lower. Knowledge score was not associated with confidence among the full sample or when stratified by training level or UDT use. The association between knowledge and confidence differed significantly by gender (interaction term p < 0.01). Adjusting for training level and UDT use, knowledge was positively associated with confidence among females (AOR 1.79, 95 % CI: 1.06, 3.30), and negatively associated with confidence among males (AOR 0.47, 95 % CI: 0.23, 0.98).


Despite poor knowledge about UDT interpretation, most resident physicians felt confident in their ability to interpret UDT results. Gender differences warrant further exploration, but even confident physicians who use UDT should evaluate their proficiency in interpreting UDT results. Educational initiatives should emphasize the complexities of UDT interpretation.