Research Design and Study Cohort
Participants were recruited following a positive screen for unhealthy alcohol use during routine screening at one of 11 primary care practices in the Greater Los Angeles VA Healthcare System (GLAVA) from February 2013 to January 2014, and were followed prospectively for 6 months. The clinical reminder system within the electronic medical record prompts providers to perform screening using the Alcohol Use Disorders Identification Test – Consumption (AUDIT-C).18 A positive screen was defined as a score of 5 or higher, the threshold used by VHA to indicate follow-up interventions.19 Additional study eligibility criteria included no AUD outpatient or inpatient encounter in the prior 90 days, at least 18 years of age, ability to speak and understand English, have a valid telephone, no cognitive impairment, and engaged in care (at least one outpatient visit within GLAVA in the prior 12 months). The RAND Human Subjects Protection Committee and the GLAVA Institutional Review Board approved all procedures.
Data Collection
Eligible patients received a letter followed by a telephone invitation. Interviewers explained study participation and obtained verbal informed consent. Baseline telephone interviews were completed an average of 15.3 days after the positive screen visit (range six to 87). Follow-up telephone interviews were conducted 6 months after the positive screen visit (mean 187.2 days, range 174 to 299). Participants received incentives for baseline ($50) and follow-up ($60).
Measures
Patient Characteristics
Gender and age were obtained from administrative records. Marital status, education, employment, race/ethnicity, income, receiving all or most care at VHA, depression symptoms,20 physical and mental health functioning,21 and drug use (illegal and prescription misuse) were collected from the baseline survey.
Process Measures
Candidate process measures were based on a review of existing measures and clinical practice guidelines and were selected and refined using a modified RAND/UCLA expert consensus panel approach22 and then operationalized, yielding a total of 21 measures.23 We applied the measures using administrative data (i.e., outpatient visits, pharmacy, laboratory) and medical record review to assess outpatient care across both primary and specialty settings in the 6 months following identification of unhealthy alcohol use (Table 1). Six measures required only administrative data, while 15 measures integrated both administrative and medical record review data. Two registered nurses used a structured abstraction tool to collect data elements from medical record text notes. Abstractors achieved high interrater reliability (percent agreement 99.1%, kappa 98.0%).
Table 1 Performance on Quality Measures for Unhealthy Alcohol Use
We defined a formative composite24 to summarize documented care processes identified by the expert panel that each patient received for unhealthy alcohol use. We created an overall percentage composite measure, defined as the proportion of individual process-based quality measures (described below) for which each patient received the recommended care relative to all for which the patient was eligible. Each eligible measure is weighted equally for each patient. Composite measures have several advantages,24,25 including the potential to increase reliability and maximize the number of patients included in the analyses relative to individual measure analyses that are limited to patients in the denominator of an individual measure. For inclusion in our composite measures, individual measures needed to have a denominator of at least 20 eligible patients, a numerator of at least four, and a pass rate no smaller than 2% and no larger than 98%. Using these 17 qualifying measures, we developed two sub-composites: (1) screening including screening and assessment for unhealthy alcohol use (eight measures: 1–7, 24; see Tables 1 and 2) and (2) treatment including brief intervention, initial discussion of treatment options, initiation of treatment, and receipt of treatment for unhealthy alcohol use (nine measures: 8–11, 15, 18, 19, 21, 25).
Table 2 Demographic and Clinical Characteristics of Study Sample at Baseline (n = 719)
Alcohol Use Measures
We assessed past 30-day drinking using the Timeline Followback (TLFB) at both baseline and follow-up.26 We examined two drinking outcomes: percent of heavy drinking days in the past 30 days out of days available (i.e., not incarcerated or hospitalized) and mean drinks per week in the past 30 days. A heavy drinking day was defined as five or more drinks for men and four or more drinks for women. Drinking above recommended weekly limits was defined as mean drinks per week of more than 14 drinks per week for men and more than seven per week for women.27 These measures are distinct from the positive alcohol screen for study eligibility, which was an AUDIT-C score of 5 or higher during a routine screen.
The goal of the baseline interview was to capture alcohol use prior to the screen-positive visit, as interventions delivered immediately following the positive screen could affect alcohol use. Past 30-day alcohol use included some days after the screen-positive visit, so we used drinking data for all days prior to the screen-positive visit for each patient to characterize baseline drinking. We imputed missing daily alcohol consumption data, both at baseline and 6-month follow-up, using a hot-deck multiple imputation approach28 (see Appendix).
Response Rate and Analytic Sample
The adjusted response rate (AAPOR response rate 129) at baseline was 54% (raw rate: 51%; 973 completes of 1922 potentially eligible). The probability of baseline non-response was not significantly associated with any characteristics available for all eligible patients (age, gender, income, marital status, or service era; results not shown). Of 1032 who consented to participate, 46 were excluded for reporting alcohol-related encounters within the past 90 days and 13 declined further participation. The follow-up adjusted response rate was 82% (raw rate, 79%; 770 completes of 973 baseline completers). Removal of patients sampled in error (e.g., updated administrative data indicated non-eligibility) resulted in a sample of 913 at baseline and 719 at follow-up. Two patients reported no days available for drinking in the past 30 days at follow-up and were excluded from modeling analyses (n = 717).
Statistical Analyses
Patient Characteristics and Receipt of Recommended Care
We used descriptive statistics, weighted for survey non-response, to describe the characteristics of the study sample and the proportion of patients who received recommended care on each quality measure.
Composite Measure Analyses
To assess the association between composite measures and risk of heavy drinking, we fit quasi-Poisson models to account for overdispersion and estimated robust standard errors for regression coefficients.30,31 We regressed the number of heavy drinking days in the 30 days preceding the follow-up interview on the target composite measure. Models were run using the overall composite as the predictor of interest, as well as separate models containing both sub-composites (assessment; treatment). All models included age, marital status, education, race/ethnicity, income, mental and physical functioning, receiving all or most care in VHA, and the baseline value of alcohol use, derived from daily drinking data preceding the positive screening visit. Since 47.6% (n = 342) reported no heavy drinking days at baseline, we also fit these models including only a targeted subset of 375 patients who had at least one heavy drinking day prior to positive screening.
We fit linear regression models for the average number of drinks per week outcome. We transformed the outcome (taking the log of the average number of drinks per week + 1) so the model would be better aligned with linear regression assumptions. Under this model, the composite quality coefficient estimate can be expressed in terms of the expected percent change in drinks per week associated with receiving all versus none of the care recommended for a patient. We adjusted for the same covariates described above. We also fit these models on a targeted subsample of 357 patients who drank above recommended weekly limits in the period prior to positive screening (i.e., > 14 drinks per week for men; > seven per week for women).
Individual Process Measure Analyses
For both alcohol consumption outcomes, we similarly examined nine individual measures: Assess for Alcohol Use Disorders, Evaluate for Suicide Risk, Screen for Other Substance Use, Test Liver Function, Conduct Brief Intervention, Discuss Treatment Options, Offer Psychosocial Intervention, Reassess Alcohol Use, and Repeat Brief Intervention. These were the subset of measures for which the sample size was sufficient to detect a medium-sized association (Cohen’s d = 0.5 standard deviations32 (SD)) between the individual measure and the logarithm of average number of drinks per week. We fit models using these measures in place of the composites for both full sample and targeted subsample analyses as described above.