of rs73568641 in an independent sample of morphine-treated patients. Evaluation of rs73568641 using clinically documented morphine dose data also helps to compensate for another limitation of our study, which is that the data on usual daily methadone dose was collected via self-report. The intensive daily nature of methadone treatment, which allows for close monitoring of clinical response and provides frequent reminders to the patient of their dose, further supports the reliability of the reported methadone dose data. One study found that when OD subjects receiving methadone were interviewed in a research setting, the correlation coefficient between self-reported and clinically documented dosage was 0.97.71
