Review of the Current State of Urine Drug Testing in Chronic Pain: Still Effective as a Clinical Tool and Curbing Abuse, or an Arcane Test?

PURPOSE OF REVIEW: Therapeutic use, misuse, abuse, and diversion of controlled substances in managing chronic non-cancer pain remain a major concern for physicians, the government, payers, and patients. The challenge remains finding effective diagnostic tools that can be clinically validated to eliminate or substantially reduce the abuse of controlled prescription drugs, while still assuring the proper treatment of those patients in pain. Urine drug testing still remains an important means of adherence monitoring, but questions arise as to its relevance and effectiveness. This review examines the role of UDT, determines its utility in current clinical practice, and investigates its relevance in current chronic pain management. RECENT FINDINGS: A review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Literature was searched from year 2000 to present examining the relevance and role of UDT in monitoring chronic opioid therapy along with reliability and accuracy, appropriate use, overuse, misuse, and abuse. There are only a limited number of reviews and investigations on UDT, despite the fact that clinicians who prescribe controlled medications for chronic states commonly are expected to utilize UDT. Therefore, despite highly prevalent use, there is a limited publication base from which to draw in this present study. Regardless of experience or training background, physicians and healthcare providers can much more adequately assess opioid therapy with the aid of UDT, which often requires confirmatory testing by a laboratory for clinical and therapeutic prescribing decisions. It has become a strongly recommended aspect of pain care with controlled substances locally, regionally, and nationally. Incorporating UDT for all patients in whom chronic opioid therapy is undertaken is consistent with state and national guidelines and best practice strategies. Practice standards vary as to the frequency of UDT locally, regionally, and nationally, however.

Use of a Screening Questionnaire to Identify Patients at Risk of Hyperglycemia Prior to Steroid Injection Therapy.

Objective: Patients with chronic pain considered for steroid injections are not consistently screened for undiagnosed or poorly controlled diabetes mellitus (DM) prior to steroid administration despite the known impact of corticosteroids on glucose control. A quality improvement project was undertaken to identify the prevalence of at-risk patients prior to steroid exposure through the development and implementation of a screening questionnaire. Subject: Three hundred and five adult patients with chronic pain who were being considered for an outpatient steroid injection were interviewed. Methods: Each patient was asked to complete an American Diabetes Association-validated diabetes mellitus screening questionnaire (ADAQ). In addition, patients responded to a set of nine questions that addressed common signs and symptoms of hyperglycemia. Results: The total prevalence of known DM in the study population was found to be 20% (60 patients), based on a documented history of diabetes mellitus. The ADAQ identified an additional 135 patients (45%) at high risk for undiagnosed DM. The full study questionnaire identified 143 patients (47.3%) who had no known history of diabetes mellitus as being at risk for hyperglycemia. In patients with known diabetes, five of nine symptom-based screening questions occurred with significantly frequency (P < 0.05): excessive thirst, excessive hunger, blurred vision, poor wound healing, and repeated infections. Conclusions: More than 60% of the patients screened had high risk of having inadequately treated DM. Thus, routine screening for DM should be considered in patients prior to treatment involving corticosteroids. The study questionnaire is a potentially cost-effective initial screening tool to determine which patients should undergo laboratory testing.

Use of a Risk-Stratification Tool in Identification of Potential Adrenal Suppression Preceding Steroid Injection Therapy in Chronic Pain Patients.

BACKGROUND: Patients who present for steroid injections are not routinely screened for potential hypothalamic-pituitary-adrenal (HPA) axis suppression from previous steroid exposure. Patients often receive various steroid therapies that are not reported by the patient or recorded in available medical records. Yet, HPA axis suppression has been reported with a single intra-articular injection. METHODS: An IRB-approved quality improvement questionnaire was implemented to comprehensively screen patients for risk of HPA axis suppression secondary to prior and/or concurrent corticosteroid use. This questionnaire was given to adult patients seen in a University Pain Management Clinic, who were being considered for a steroid injection, to define the extent of exposure to corticosteroids either by mouth, topically, inhaled, or systemic/local injection within the past 6 months. RESULTS: Two hundred patients completed the questionnaire. Eighty-nine patients (44.5%) screened positive for significant steroid exposure with a screen score of three or above. The average score for the screen positive group was 6.31 ± 3.47 (range 3-22). Women were 1.9 times more likely to screen positive than men (53.4% vs 27.5%, P < 0.0004). Otherwise, the screen positive and screen negative groups were similar in demographic characteristics (age, BMI, and diabetes status). CONCLUSIONS: Our results suggest that patients receive steroids from many sources and may be at risk for HPA axis suppression. Further testing is necessary to determine if these patients indeed have biochemical evidence of adrenal suppression. Utilization of a screening questionnaire might help identify patients who should be considered for HPA axis testing prior to steroid injections.

Direct measurement of the lethal isotherm for radiofrequency ablation of myocardial tissue.

BACKGROUND: The lethal isotherm for radiofrequency catheter ablation of cardiac myocardium is widely accepted to be 50°C, but this has not been directly measured. The purpose of this study was to directly measure the tissue temperature at the edge of radiofrequency lesions in real time using infrared thermal imaging. METHODS AND RESULTS: Fifteen radiofrequency lesions of 6 to 240 seconds in duration were applied to the left ventricular surface of isolated perfused pig hearts. At the end of radiofrequency delivery, a thermal image of the tissue surface was acquired with an infrared camera. The lesion was then stained and an optical image of the lesion was obtained. The thermal and optical images were electronically merged to allow determination of the tissue temperature at the edge of the lesion at the end of radiofrequency delivery. By adjusting the temperature overlay display to conform with the edge of the radiofrequency lesion, the lethal isotherm was measured to be 60.6°C (interquartile ranges, 59.7° to 62.4°C; range, 58.1° to 64.2°C). The areas encompassed by the lesion border in the optical image and the lethal isotherm in the thermal image were statistically similar and highly correlated (Spearman ρ=0.99, P<0.001). The lethal isotherm temperature was not related to the duration of radiofrequency delivery or to lesion size (both P>0.64). The areas circumscribed by 50°C isotherms were significantly larger than the areas of the lesions on optical imaging (P=0.002). CONCLUSIONS: By direct measurement, the lethal isotherm for cardiac myocardium is near 61°C for radiofrequency energy deliveries <240 seconds in duration. A 50°C isotherm overestimates lesion size. Accurate knowledge of the lethal isotherm for radiofrequency ablation is important to clinical practice as well as mathematical modeling of radiofrequency lesions.

Effect of electrode orientation on lesion sizes produced by irrigated radiofrequency ablation catheters.

BACKGROUND: Irrigated radiofrequency (RF) ablation catheters may produce different lesion sizes dependent upon the electrode orientation to the tissue. This study examined the effect of irrigated electrode orientation on the lesion size and explores a potential mechanism for this effect. METHODS AND RESULTS: Lesions were created in isolated porcine myocardium using an open irrigation, closed irrigation, and nonirrigated RF catheter (all 3.5-4 mm tips). Lesions were created with the electrodes with all permutations of electrode orientation (vertical or horizontal), contact pressure (6 or 20 g), and saline superfusate flow (0.2 or 0.4 m/sec) over tissue interface. The effect of electrode irrigation without RF delivery on tissue temperature was assessed with intramyocardial temperature probes and infrared thermal imaging. For both irrigated catheters, the horizontal orientation produced 25-30% smaller lesion volumes than the vertical orientation despite equal or greater power deliveries. The horizontal orientation produced larger lesion volumes for the nonirrigated catheter. Higher superfusate flow rates were associated with decreased lesion volumes for the irrigated catheters but greater lesion volumes for the nonirrigated catheter. Catheter irrigation alone without RF delivery reduced intramyocardial temperatures up to 4.9 degrees C and the horizontal orientation produced a 2-fold greater area of tissue cooling than the vertical orientation. CONCLUSION: Horizontal electrode orientations reduce lesion volumes for irrigated RF catheters. This effect may be in part due to greater areas of active tissue cooling in the horizontal orientation.