METHODS OF NORMALIZING MEASURED DRUG CONCENTRATIONS AND TESTING FOR POTENTIAL NON-COMPLIANCE WITH A DRUG TREATMENT REGIMEN
Methods for monitoring subject compliance with a prescribed treatment regimen are disclosed. In an embodiment, the method comprises measuring a drug level in fluid of a subject and normalizing the measured drug level as a function of one or more parameters associated with the subject. The drug level can be normalized using second order quantile regression. Embodiments of the methods can use both primary and secondary metabolites in the normalization; allow changing variance by dose; allow asymmetry in variance above and below the estimated median values; and/or use analytic variables with stable estimates, such as, for example, variables associated with the percentile for −1 standard deviation, the percentile for 0 standard deviation, and the percentile for +1 standard deviation.
1 . A method of determining non-compliance with a prescribed drug regiment in a subject, the method comprising:
determining a prescribed daily dose of drug in a subject;
determining an age, a weight and a gender of the subject;
measuring a concentration of creatinine and a concentration of a primary metabolite of the drug in urine of the subject;
determining a normalized metabolite concentration as a function of parameters comprising the concentration of creatinine, the concentration of the primary metabolite, the age, the weight and the gender of the subject;
determining a quantile regression dose-based value for each of a plurality of standard deviation values, the plurality of standard deviation values relative to a mean normalized drug concentration derived from samples of a population;
comparing the normalized metabolite concentration to the quantile regression dose-based value for one of the plurality of standard deviation values;
determining a preliminary standard score based at least partially on comparison of the normalized metabolite concentration to the quantile regression dose-based value;
determining a final standard score based at least partially on the preliminary standard score; and
comparing the final standard score to an upper threshold and a lower threshold that are predetermined and standardized.
2 . The method of claim 1 further comprising measuring a concentration of a secondary metabolite in the urine of the subject, wherein the parameters used in determining the normalized metabolite concentration comprise the concentration of the secondary metabolite.
3 . The method of claim 2 wherein the parameters used in determining the normalized metabolite concentration consist of the concentration of creatinine, the concentration of the primary metabolite, the concentration of the secondary metabolite, the age, the weight and the gender of the subject.
4 . The method of claim 1 wherein the plurality of standard deviation values are a −1 standard deviation value, a 0 standard deviation value, and a +1 standard deviation value.
5 . The method of claim 4 further comprising comparing the normalized metabolite concentration to the quantile regression dose-based value for the 0 standard deviation value.
6 . The method of claim 5 further comprising comparing the normalized metabolite concentration to at least one of the quantile regression dose-based value for the −1 standard deviation value or the quantile regression dose-based value for the +1 standard deviation value.
7 . The method of claim 1 further comprising determining if the prescribed daily dose of the drug is less than a maximum daily dose of the drug before measuring the concentration of creatinine and the concentration of the primary metabolite of the opioid in the urine.
8 . The method of claim 1 wherein the quantile regression dose-based value is based at least partially on a natural log of the prescribed daily dose.
9 . The method of claim 1 wherein the quantile regression dose-based value is based at least partially on one or more coefficients derived from the samples of the population.
10 . The method of claim 1 wherein the final standard score is based at least partially on one or more adjustment variables derived from the samples of the population.
11 . The method of claim 1 wherein a plurality of members are assigned to the population based on a dose administered to the plurality of members and the presence or absence of one or more exclusion criteria selected from the group consisting of high drug metabolism, low drug metabolism, lab abnormalities, impaired kidney or liver function, use of drugs with overlapping metabolites on the same day, an inconsistent schedule of medication administration, and combinations thereof.
12 . The method of claim 1 wherein the drug is selected from the group consisting of controlled-release oxycodone, oxycodone, controlled release morphine, morphine, extended release morphine hydrocodone, methadone, and a combination of controlled-release oxycodone and oxycodone.
13 . The method of claim 1 wherein the parameters consist of the concentration of creatinine, the concentration of the primary metabolite, the age, the weight and the gender of the subject.
14 . The method of claim 1 further comprising determining if the subject is compliant with a drug regimen that includes the prescribed daily dose of the drug.
15 . The method of claim 1 wherein the primary metabolite is the drug.
16 . The method of claim 1 wherein the drug is an opioid or an antipsychotic drug.