On-site Evaluation of Substances Consumption on Opiate Maintenance

Overview

In France, General Practitioners (GPs) are widely involved in opiate maintenance treatment (OMT) by initially prescribing buprenorphine and monitoring patients under buprenorphine and methadone. Number of treated patients is around 150,000 with 75% of them treated by buprenorphine. Among the guidelines for improving OMT, urine testing is mandatory for initiating methadone, whereas it is recommended for initiating buprenorphine and during follow-up. Urine drug tests are based on immunoassay techniques and enable a qualitative analysis of the recent drug consumption, with detection based on designated thresholds, allow a better appraisal of drug exposure, before initiating and during OMT. While intrinsic diagnostic value of these tests is already demonstrated, the consequences of carrying out these tests on OMT have not been clearly established. Some studies suggest that patients exposed to drug tests may have a better OMT retention and in patients treated by methadone, performing urine screening tests has been shown to be associated with a mortality risk reduction in a Scottish retrospective cohort of opioid addicts. Actually, despite the recommendations to perform these tests, few GP prescribe tests, and few patients are regularly screened. Availability of commercial kits for urine drug testing in the medical office should improve their utilisation. The widespread of urine drug screening tests use in ambulatory care is a reality for some GPs working in addictology networks. Despite a global benefit reported in the literature with a better control in prescribing OMT and a better patients' adherence, as far as the investigators know, no study has yet explored the impact of the use of urine drug screening test in decision making in general practice with an intervention study.

In a retrospective cohort study of methadone users performed through data obtained from a primary care prescription registry in Tayside, Scotland, McCowan et al examined the interaction of patient related factors and prescribing factors at the individual level and assess their independent impact on the risk of both all-cause mortality and drug dependent cause specific mortality (McCowan, Kidd et al. 2009). Overall, 181 (8%) people died among 2378 subjects with a median follow-up of 4.38 years. Overuse of methadone, history of psychiatric admission, and increasing comorbidity were all associated with an increase in all-cause mortality. Longer duration of use (adjusted hazard ratio 0.95, 0.94 to 0.96), history of having urine tested (0.33, 0.22 to 0.49), and increasing time since last filled prescription were protective in relation to all-cause mortality. These factors are likely to be markers of people who are stabilised on maintenance treatment and engaged in monitoring procedures or who have successfully completed a methadone treatment reduction programme. This community based study gives a clear indication of the prescribing, monitoring, and management of patients in OMT and the subsequent impact on all cause and drug dependent mortality. This study provides evidence that recommendations on best practice (including specifically performing UDS) improve patients' outcomes. Using data from the French "Methaville" trial, Roux et al (Roux, Michel et al. 2012; Roux, Lions et al. 2013) investigated the effect of pre-treatment and in-treatment factors on long-term non-adherence to this OMT. Four pre-treatment predictors of non-adherence were identified: being female, not having stable housing, alcohol consumption and cocaine use. These findings highlight the need to appropriately assess psychoactive drug use when starting OMT, and urine drug testing should be consider as a way to reach this aim. On the basis of the literature, one would suppose that carrying out UDS would provide an improvement in the management of patients with abuse or addiction and would be helpful, particularly in community office-based settings, as office-based management of opioid dependence grows up (Walley, Alperen et al. 2008). Despite the lack of significant evidence of efficacy, UDS are recommended to assess the use of psychoactive substances when abuse or addiction is suspected.