Psychometric Performance of a Substance Use Symptom Checklist to Help Clinicians Assess Substance Use Disorder in Primary Care

Abstract

Importance: Substance use disorders (SUDs) are underrecognized in primary care, where structured clinical interviews are often infeasible. A brief, standardized substance use symptom checklist could help clinicians assess SUD.

Objective: To evaluate the psychometric properties of the Substance Use Symptom Checklist (hereafter symptom checklist) used in primary care among patients reporting daily cannabis use and/or other drug use as part of population-based screening and assessment.

Design, setting, and participants: This cross-sectional study was conducted among adult primary care patients who completed the symptom checklist during routine care between March 1, 2015, and March 1, 2020, at an integrated health care system. Data analysis was conducted from June 1, 2021, to May 1, 2022.

Main outcomes and measures: The symptom checklist included 11 items corresponding to SUD criteria in the Diagnostic and Statistical Manual for Mental Disorders (Fifth Edition) (DSM-5). Item response theory (IRT) analyses tested whether the symptom checklist was unidimensional and reflected a continuum of SUD severity and evaluated item characteristics (discrimination and severity). Differential item functioning analyses examined whether the symptom checklist performed similarly across age, sex, race, and ethnicity. Analyses were stratified by cannabis and/or other drug use.

Results: A total of 23 304 screens were included (mean [SD] age, 38.2 [5.6] years; 12 554 [53.9%] male patients; 17 439 [78.8%] White patients; 20 393 [87.5%] non-Hispanic patients). Overall, 16 140 patients reported daily cannabis use only, 4791 patients reported other drug use only, and 2373 patients reported both daily cannabis and other drug use. Among patients with daily cannabis use only, other drug use only, or both daily cannabis and other drug use, 4242 (26.3%), 1446 (30.2%), and 1229 (51.8%), respectively, endorsed 2 or more items on the symptom checklist, consistent with DSM-5 SUD. For all cannabis and drug subsamples, IRT models supported the unidimensionality of the symptom checklist, and all items discriminated between higher and lower levels of SUD severity. Differential item functioning was observed for some items across sociodemographic subgroups but did not result in meaningful change (<1 point difference) in the overall score (0-11).

Conclusions and relevance: In this cross-sectional study, a symptom checklist, administered to primary care patients who reported daily cannabis and/or other drug use during routine screening, discriminated SUD severity as expected and performed well across subgroups. Findings support the clinical utility of the symptom checklist for standardized and more complete SUD symptom assessment to help clinicians make diagnostic and treatment decisions in primary care.

Figure 1.. Process of Selecting Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) Substance Use Symptom Checklists for Inclusion in Analyses

DSM-5 Substance Use Symptom Checklists are typically administered after a positive cannabis and/or other drug use screen, as part of routine primary care. Positive cannabis and/or other drug use screens were used to define subsamples in which to test the psychometric properties of the checklist. A single, random checklist for each subsample was selected. ^aCannabis screens were considered positive if a patient indicated daily or almost daily cannabis use in the past year. ^bOther drug screens were considered positive if a patient indicated any other drug use in the past year.

Figure 2.. Item Characteristic Curves for 11 Substance Use Disorder (SUD) Criteria on the Substance Use Symptom Checklist

Item characteristic curves among primary care patients who reported daily cannabis use only (n = 16 140) (A), other drug use only (n = 4791) (B), and both daily cannabis and other drug use (n = 2373) (C) on routine screening from March 1, 2015, to March 1, 2020. Each of the 11 criteria is represented as a separate curve. The slope of the curve corresponds to the discrimination parameter a. The point where each line intersects the dashed horizontal line indicates the level of latent SUD severity where patients have a 50% probability of endorsing the criterion, which corresponds to the severity parameter b.