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Use of an algorithm applied to urine drug screening to assess adherence to an OxyContin® regimen

Joseph E. Couto, PharmD, MBA, Lynn Webster, MD, FACPM, FASAM, Martha C. Romney, MS, JD, MPH, Harry L. Leider, MD, MBA, Ariel Linden, DrPH, MS


Objective: This study examined the ability of an algorithm applied to urine drug levels of oxycodone in healthy adult volunteers to differentiate among low, medium, and high doses of OxyContin®.
Participants and interventions: Thirty-six healthy volunteers were randomized to receive 80, 160, or 240 mg of daily OxyContin® to steady state while under a naltrexone blockade. During days 3 and 4 of the study, urine samples of all participants were collected, and oxycodone levels detected in the urine were obtained using a liquid chromatography-mass spectrometry (LC-MS-MS) assay.
Outcome measures: The concordance was calculated for raw and adjusted LC-MS-MS urine oxycodone values within each study participant between their third and fourth day values. Also, an analysis of medians was calculated for each of the dosage groupings using Bonett-Price confidence intervals for both raw and adjusted LC-MS-MS values.
Results: The concordance correlation coefficient for the raw LC-MS-MS values between days 3 and 4 was 0.689 (95% confidence intervals = 0.515, 0.864), whereas the concordance correlation coefficient for the LC-MS-MS values using the algorithm (ie, normalized values) was 0.882 (95% confidence intervals = 0.808, 0.956). Because of greater variability in the raw values, some overlap was observed in the confidence intervals of the various OxyContin® doses, whereas no overlap was observed in the normalized confidence intervals regardless of the application of a Bonferroni adjustment.
Conclusions: In contrast to raw LC-MS-MS values, an algorithm that normalizes oxycodone urine drug levels for pH, specific gravity, and lean body mass discriminates well among all three of the daily doses of OxyContin® tested (80, 160, and 240 mg), even with correcting for multiple analyses.


urine drug testing, medication adherence, OxyContin®, oxycodone, algorithm

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Substance Abuse and Mental Health Services Administration: National estimates from the drug abuse warning network [homepage on the Internet]. Washington, DC: Substance Abuse and Mental Health Services Administration. Available at Accessed July 13, 2009.

Office of Applied Studies: Results from the 2007 National Survey on Drug Use and Health: National Findings. Rockville, MD: Substance Abuse and Mental Health Administration, 2008.

Kell MJ: Utilization of plasma and urine methadone concentrations to optimize treatment in maintenance clinics. I. Measurement for a clinical setting. J Addict Dis. 1994; 13(1): 5-26.

Kell MJ: Utilization of plasma and urine methadone concentration measurements to limit narcotics use in methadone maintenance patients. II. Generation of plasma concentration response curves. J Addict Dis. 1995; 14(1): 85-108.

Purdue Pharma L.P.: OxyContin [package insert]. Stamford, CT: Purdue Pharma L.P., 2009.

Lin LI: A concordance correlation coefficient to evaluate reproducibility. Biometrics. 1989; 45: 255-268.

Lin LIK: A note on the concordance correlation coefficient. Biometrics. 2000; 56: 324-325.

Bonett DG, Price RM: Statistical inference for a linear function of medians: Confidence intervals, hypothesis testing, and sample size requirements. Psychological Methods. 2002; 7: 370-383.

Price RM, Bonett DG: Estimating the variance of the sample median. J Stat Comput Simul. 2001; 68: 295-305.

Price RM, Bonett DG: Distribution-free confidence intervals for difference and ratio of medians. J Stat Comput Simul. 2002; 72: 119-124.

Steichen TJ, Cox NJ: Concordance correlation coefficient. Stata Tech Bull. 1998; 43: 35-39.

Steichen TJ, Cox NJ: Software update for concord. Stata J. 2008; 8(4): 594.

Cox NJ: Speaking stata: Graphing agreement and disagreement. Stata J. 2004; 4(3): 329-349. [homepage on the Internet]. Stata Corporation. Available at Accessed May 1, 2009.

Newson R: BPMEDIAN: Stata module to compute Bonett-Price confidence intervals for medians and their contrasts [homepage on the Internet]. Statistical Software Components (SSC). Available at Accessed June 3, 2009.

Ingelman-Sundberg M: Genetic polymorphisms of cytochrome P450 2D6 (CYP2D6): Clinical consequences, evolutionary aspects and functional diversity. Pharmacogenomics J. 2005; 5: 6-13.

Evans WE, Relling MV, Rahman A, et al.: Genetic basis for a lower prevalence of deficient CYP2D6 oxidative drug metabolism phenotypes in Black Americans. J Clin Invest. 1993; 91: 2150-2154.

Bradford LD: CYP2D6 allele frequency in European Caucasians, Asians, Africans and their descendants. Pharmacogenomics. 2002; 3(2): 229-243.



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