Alcohol-Related Hospitalizations During the Initial COVID-19 Lockdown in Massachusetts: An Interrupted Time-Series Analysis
Background: The effect of initial COVID-19 pandemic–associated lockdowns on alcohol-related hospitalizations remains uncertain. This study compares alcohol-related hospitalizations at a US Department of Veterans Affairs (VA) system in Massachusetts before, during, and after the initial COVID-19 lockdown.
Methods: This study is an interrupted time-series analysis at the VA Boston Healthcare System. Participants included all patients hospitalized on the medical, psychiatry, and neurology services at VA Boston Healthcare System from January 1, 2017, to December 31, 2020, excluding those under observation status. The period January 1, 2017, to March 9, 2020, was defined as prelockdown (the reference group); March 10, 2020, to May 18, 2020, was lockdown; and May 19, 2020, to December 31, 2020, was postlockdown. Alcohol-related hospitalizations were determined using International Statistical Classification of Diseases, Tenth Revision primary diagnosis codes.
Results: We identified 27,508 hospitalizations during the study periods. There were 72 alcohol-related hospitalizations per 100,000 patient-months during the prelockdown period, 10 per 100,000 patient-months during the lockdown, and 46 per 100,000 patient-months in the postlockdown period. Compared with the prelockdown period, the adjusted rate ratio for daily alcohol-related hospitalizations during lockdown was 0.20 (95% CI, 0.10-0.39) vs 0.72 (95% CI, 0.57-0.92) after the lockdown. A similar pattern was observed for all-cause hospitalizations.
Conclusions: Our results suggest that COVID-19 pandemic lockdown measures were associated with fewer alcohol-related hospitalizations. Proactive outreach for vulnerable populations during lockdowns is needed.
Methods
We conducted an interrupted time-series analysis including all inpatient hospitalizations at VABHS from January 1, 2017, to December 31, 2020, to compare the daily number of alcohol-related hospitalizations across 3 exposure groups: prelockdown (the reference group, 1/1/2017-3/9/2020); lockdown (3/10/2020-5/18/2020); and postlockdown (5/19/2020-12/31/2020).
The VA Corporate Data Warehouse at VABHS was queried to identify all hospitalizations on the medical, psychiatry, and neurology services during the study period. Hospitalizations were considered alcohol-related if the International Statistical Classification of Diseases, Tenth Revision (ICD-10) primary diagnosis code (the main reason for hospitalization) was defined as an alcohol-related diagnosis by the VA Centralized Interactive Phenomics Resource (eAppendix 1, available online at doi:10.1278/fp.0404). This database, which has been previously used for COVID-19 research, is a catalog and knowledge-sharing platform of VA electronic health record–based phenotype algorithms, definitions, and metadata that builds on the Million Veteran Program and Cooperative Studies Program.14,15 Hospitalizations under observation status were excluded.
To examine whether alcohol-related hospitalizations could have been categorized as COVID-19 when the conditions were co-occurring, we identified 244 hospitalizations coded with a primary ICD-10 code for COVID-19 during the lockdown and postlockdown periods. At the time of admission, each hospitalization carries an initial (free text) diagnosis, of which 3 had an initial diagnosis related to alcohol use. The population at risk for alcohol-related hospitalizations was estimated as the number of patients actively engaged in care at the VABHS. This was defined as the number of patients enrolled in VA care who have previously received any VA care; patients who are enrolled but have never received VA care were excluded from the population-at-risk denominator. Population-at-risk data were available for each fiscal year (FY) of the study period (9/30-10/1); the following population-at-risk sizes were used: 38,057 for FY 2017, 38,527 for FY 2018, 39,472 for FY 2019, and 37,893 for FY 2020.
The primary outcome was the daily number of alcohol-related hospitalizations in the prelockdown, lockdown, and postlockdown periods. A sensitivity analysis was performed using an alternate definition of the primary outcome using a broader set of alcohol-related ICD-10 codes (eAppendix 2, available online at doi:10.1278/fp.0404).
Statistical Analysis
To visually examine hospitalization trends during the study period, we generated a smoothed time-series plot of the 7-day moving average of the daily number of all-cause hospitalizations and the daily number of alcohol-related hospitalizations from January 1, 2017, to December 31, 2020. We used multivariable regression to model the daily number of alcohol-related hospitalizations over prelockdown (the reference group), lockdown, and postlockdown. In addition to the exposure, we included the following covariates in our model: day of the week, calendar date (to account for secular trends), and harmonic polynomials of the day of the year (to account for seasonal variation).16
We also examined models that included the daily total number of hospitalizations to account for the reduced likelihood of hospital admission for any reason during the pandemic. We used generalized linear models with a Poisson link to generate rate ratios and corresponding 95% CIs for estimates of the daily number of alcohol-related hospitalizations. We estimated the population incidence of alcohol-related hospitalizations per 100,000 patient-months for the exposure periods using the population denominators previously described. All analyses were performed in Stata 16.1.
