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IIR 10-347 – HSR Study

IIR 10-347
Drug Screen for Primary Care Patients
Quyen Q. Tiet, PhD
VA Palo Alto Health Care System, Palo Alto, CA
Palo Alto, CA
Funding Period: July 2011 - June 2015
Drug use disorders (DUDs) are under-detected and under-treated in VA primary care and mental health systems (e.g., Ananth et al., 1989; Blow et al, 2005; Rosenheck, 2004; Tracy et al., 2007). Many guidelines recommend screening for drug use, further assessment for those screening positive, and referral of patients with DUDs to substance use disorder (including alcohol and illicit drugs) specialty treatment (Substance Abuse and Mental Health Services Administration, 2005; Sullivan & Fleming, 1997; VA/DoD Evidence-based Clinical Practice Guideline Working Group, 2001; Veterans Health Administration, 2005). However, such guidelines have no recommendation for specific screening instrument. Drug screening is not conducted routinely in the VA, and no available drug-screening instrument is sufficiently brief and is suitable for the primary care settings in VA (Berman et al., 2005; McPherson & Hersch, 2000; Tiet et al., 2008; U. S. Preventive Services Task Force, 2008). The U. S. Preventive Services Task Force (USPSTF, 2008) conducted a review on current standardized screening instruments and came to the same conclusion as our review (Tiet et al., 2008) that currently available screening instruments are not brief enough "when applied in a busy primary care practice setting."

The overarching goal of this study was to establish a brief and practical screening instrument for VA patients in the primary care settings to detect (a) DUDs and (b) drug-related consequences and problems for patients who might not meet diagnostic criteria for a DUD. There were three primary aims for this project. Aim 1 was to revise, shorten, and examine the sensitivity and specificity of six existing drug screening instruments for patients seeking services in primary care settings so that they are more appropriate for use in VA primary care settings. These revised instruments were evaluated in terms of how well they detect (a) DUDs, and (b) drug-related consequences and problems in patients who may, or may not, meet diagnostic criteria for a DUD. Aim 2 was (a) to develop a new instrument from combining items across the existing instruments, and (b) to identify the best instrument (considering the relative number of false positives and false negatives) by comparing the six revised, shortened, existing instruments and the newly constructed instrument. Aim 3 was to examine how well the best performing drug screening instrument performs in detecting DUDs and drug-related problems among primary care patients with and without PTSD. Aim 4 (secondary aim) was to examine the prevalence of DUD in VA primary care settings.

The proposed project recruited patients (N=1,300) from VA primary care settings at the VA Palo Alto Health Care System, CA. Research staff recruited and consented participants in person. Individuals who agreed to participate completed an interview that gathered demographic information and data on overall health, drug use and related behaviors, consequences, problems and a diagnostic interview. The interview, on average, took 40 minutes. Patients who agreed to participate completed the interview that included information about their demographic characteristics, items from six existing revised drug screening intruments, a measure of drug use consequence, and a diagnostic interview. One hundred randomly selected participants were re-administered the drug screening instruments for one-week test-retest reliability analyses. The proposed study revised items from six existing instruments. The six existing instruments are: (1) the Two-item Conjoint Screening (TICS; Brown et al., 1997), (2) CAGE-Adapted to Include Drugs (CAGE-AID; Brown & Rounds, 1995), (3) the Drug Use Disorders Identification Test (DUDIT; Berman et al., 2005), (4) Alcohol, Smoking and Substance Involvement Screening Test (ASSIST; Newcombe et al., 2005), (5) the Drug Abuse Screen Test (DAST; Skinner, 1982), and (6) the Single-Question Screening Test (SQST; Smith, et al., 2010). Based on sensitivity and specificity levels, the best identified items were selected. Area under the ROC curve (AUC) was used to compare the revised drug screening instruments.

The study recruited 1,300 participants, with 17 participants excluded, and a total final sample of 1,283. The current demographic breakdown includes 95% males, 55% Non-Hispanic/Caucasians. Diagnostically, 10.4% had drug use abuse/dependence disorder, 12.8% had alcohol use abuse/dependence disorder, and 14.9% had PTSD diagnosis disorder.

We have completed the main objectives of the study--to develop and validate a screen of drug use (SoDU) that is brief and easy to use in primary care settings (Tiet et al., in press). We revised items drawn from existing screening instruments. We conducted item performance analyses using half of the sample ("development sample") to select the best and most parsimonious items. We then validated the chosen items for diagnostic accuracy on the other half of the sample ("validation sample"), and examined the performance of the SoDU on sub-groups of patients, including age, gender, race/ethnicity, marital status, educational levels, and posttraumatic stress disorder status.

Signal detection analyses on data from the development sample identified the two items-and their cut-points-for the SoDU that provided the best predictive performance for both the DUD and the DUNC criteria. For drug use disorder, the SoDU was 100% sensitive and 93.7% specific; for drug use negative (DUD)consequences (DUNC), it was 93.2% sensitive and 96.0% specific. We then tested the SoDU on the validation sample. In that sample, the SoDU was 92.3% sensitive and 92.9% specific for DUD, and 83.2% sensitive and 96.9% specific for DUNC. Test-retest reliability of the SoDU, as based on 100 participants retested after one week, resulted in a kappa of .9. Sensitivity and specificity of the SoDU were comparable across all sub-groups of patients on both criteria. Other criteria (e.g., positive and negative likelihood ratios, rate of positive test, etc.) were also comparable among these subgroups of patients.

We find that the two-item Screen of Drug Use (SoDU) is a suitable screening instrument for both drug use disorders and drug use negative consequences in VA primary care clinics. It is clear and brief, consisting of one or potentially two questions. Its sensitivity and specificity are excellent for both criteria, and for patient groups varying on gender, racial/ethnicity, marital status, educational level, and PTSD status. Furthermore, the SoDU would be an effective addition to health care system screening tools due to its excellent efficiency and low positive test rates.

In addition, we have developed and validated a brief version, a two-item Ti-ASSIST, to improve efficiency of screening of illicit substance use in PC (Tiet et al, in review). The Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) is a screening instrument to detect substance use in primary care (PC). To screen for illicit substances (excluding tobacco and alcohol), the ASSIST consists of 8 to 57 questions and requires complicated scoring. A brief, two-item version (Ti-ASSIST) was identified. Based on the development sample, the Ti-ASSIST was 94.12% sensitive and 89.57% specific for drug use disorder. Based on the validation sample, it was 95.38% sensitive and 87.83% specific. The Ti-ASSIST also had comparable sensitivity and specificity for drug use negative consequences, as well as for diverse subgroups of patients in terms of gender, age, race/ethnicity, marital status, educational levels, and posttraumatic stress disorder status. The Ti-ASSIST may be a useful screening tool for PC settings. It is reliable, brief, and easy to administer and score. It is sensitive and specific for drug use disorders and drug use negative consequences, and the psychometric properties are consistent across subgroup of patients.

A brief, validated, and easy-to-use drug screening instrument would have wide-ranging benefits to patients with and without PTSD and the VA health care systems. Early detection and interventions are associated with better psychiatric and drug-related outcomes, and reduction in health care costs (e.g., Center for Substance Abuse Treatment, 2005; Clark et al., 1998). With respect to research benefits, a validated drug screening instrument could be the foundation for future studies to identify patients in the primary care settings who require different intensities of interventions (e.g., psychoeducation or substance use disorder treatment) for their DUDs or drug-related problems. We will build on the current project to examine in future studies how this screening instrument could be used to differentiate among patients who may need only brief interventions provided in the primary care settings, and those who should be referred to specialty substance use disorder or dual diagnosis integrative care for patients with PTSD and substance use disorders. We are in the process of developing a study proposal to examine the efficicay of a telephone intervention protocol. In addition, future implementation projects will be conducted to improve procedures for integration of drug screening into VA primary care settings. Thus, a long-term potential impact of the proposed study is information that can lead to the development of VA practice guidelines for screening and managing DUDs or related problems in the primary care system, and to make detection, assessment, treatment, management or referral for treatment of patients with drug-related problems an integral part of the primary care system in the VA. Once a brief, validated drug screen is available for VA primary care patients, it could be modified and further validated for use with patients seen in other settings of medical care, and with other populations in the VA, such as young veterans or recent returnees from the Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF).

The diagnostic accuracy of the newly developed screen of drug use (SoDU) has been accepted for publication (in press) in JAMA Internal Medicine. The SoDU has been promoted through JAMA network mechanisms (on-line first publication, Tweet post, promotional images, etc.) and VA Palo Alto press release. It has received a review in JAMA IM underlining the importance of such a screening instrument. It is still early to assess the actual impact of the availability of this instrument at this time.

External Links for this Project

NIH Reporter

Grant Number: I01HX000516-01A1

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None at this time.

DRA: Substance Use Disorders, Health Systems, Mental, Cognitive and Behavioral Disorders
DRE: Diagnosis
Keywords: none
MeSH Terms: none

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