1. 2016;19;89-100Impact of Urine Drug Screening on No Shows and Dropouts among Chronic Pain Patients: A Propensity-Matched Cohort Study
   Prospective Evaluation
   Parthasarathy Krishnamurthy, PhD, Govindaraj Ranganathan, MD, Courtney Williams, MD, and Gulshan Doulatram, MD.

BACKGROUND: The last 2 decades have seen a substantial increase in both the prescription of opioids for managing chronic pain, and an increase in opioid-related deaths in the US. Urine drug screening (UDS) is the de facto monitoring tool aimed at detecting and deterring opioid misuse.

OBJECTIVE: We study whether administering UDS on pain patients influences post-screening behavior of no-shows and dropouts.

STUDY DESIGN: Observational cohort study of electronic medical records.

SETTING: Single urban academic pain-clinic.

METHODS: A retrospective cohort comparison of patients receiving UDS versus those not receiving UDS was conducted on the entire sample as well as in the propensity score-matched samples in which matching was based on age, gender, pain-score, procedure-scheduled, systolic and diastolic blood pressure (BP), pulse, temperature, physician ID, year of visit, psychology referral, and opioid prescription in the first visit. In addition, we conducted within-subjects logistic-regression to study no-shows and non-proportional hazards survival modeling to study dropout.

RESULTS: Analyses of 4,448 clinic visits by 723 pain patients indicated that UDS exposure in the first visit is associated with increased risk of no-show in the second visit (OR = 2.73, P < .0001); no-show rate was 10.24% for those without UDS compared to 23.75% for those with a UDS. Among those tested, the no-show rate was higher for those testing positive for illicit substances (34.57%) than for those testing negative (21.74%). These findings were replicated in 8 different propensity-score matched subsamples aimed at addressing potential non-random selection, as well as in within-subject analysis accounting for individual-level no-show propensity. Non-proportional hazards survival analysis shows that risk of dropout increased by 100.3% with every additional UDS (HR 95% CI: 1.54 to 2.61).

LIMITATIONS: Retrospective design, non-randomized sample, single-setting.

CONCLUSIONS: The results indicate that UDS is associated with increased no-shows and dropout from clinic subject to limitations of observational studies such as selection bias and confound by unobserved variables. These results serve as a call for additional prospective randomized studies to understand the impact of UDS, and where the patients might go when they dropout from the clinic.