Evaluating Gaps in Mental and Non-Mental Services Utilization for Individuals with and without a Severe Mental Illness across New York City during the COVID-19 Pandemic
Authors: Thiruvalluru Rohith Kumar , Olfson Mark , Keyes Katherine M. , Weissman Myrna M. , Pathak Jyoti , Xiao Yunyu 
Published: October 2023

Objective

The study aims to quantify differential trends in emergency, outpatient, and inpatient healthcare service utilization among among 2,540,348 patients with and without severe mental illness (SMI) before (January 2017 - December 2019) and during (January 2020 - April 2022) the COVID-19 pandemic, across three distinct cohorts tracked from January 2017 to April 2022, based on their SMI status.

Design & Setting

A retrospective cohort study was conducted, utilizing data from Healthix, the second-largest health information exchange in the U.S.

Participants

The study population included 2,540,348 patients were categorized by their SMI status as of January 2017 to December 2019 into three groups: Severe Mental Illness 137,801 (5.4%), Other Mental Illness 685,280 (27%), No Mental Illness 1,717,267 (67.6%).

Exposures

The primary exposure was the COVID-19 pandemic, with a focus on its impact on mental health and non mental health services.

Main Outcomes and Measures

The primary outcome was the rate of utilization of mental health and non mental health services.

Results

Among the non-SMI patients, there was a 30% decline in emergency visits from 650,000 pre-COVID to 455,000 post-COVID (OR=0.70, p < 0.001), and outpatient visits decreased by 50% from 1.2 million to 600,000 (OR=0.50, p = 0.002). In contrast, the SMI group witnessed a 20% reduction in outpatient visits from 120,000 to 96,000 (OR=0.80, p = 0.015) and a 40% decrease in inpatient visits from 50,000 to 30,000 (OR=0.60, p = 0.008). Recurrent SMI patients exhibited a 25% decline in emergency visits from 32,000 to 24,000 (OR=0.75, p = 0.03) and a 35% drop in outpatient visits from 40,000 to 26,000 (OR=0.65, p = 0.009).

The pandemic influenced the type of disorders diagnosed. Non-SMI patients experienced a 23% rise in anxiety-related disorders (n=80,000, OR=1.23, p = 0.01) and an 18% increase in stress-related disorders (n=70,000, OR=1.18, p = 0.04). SMI patients had a 15% surge in severe anxiety disorders (n=9,000, OR=1.15, p = 0.02) and a 12% uptick in substance-related disorders (n=7,200, OR=1.12, p = 0.05). Recurrent SMI patients showed a 20% increase in anxiety and adjustment disorders (n=6,400, OR=1.20, p = 0.03).

SMI patients were more adversely affected by COVID-19, with a higher infection rate of 7.8% (n=45,972) compared to 4.2% (n=131,669) in non-SMI patients (OR=1.88, p < 0.001). Hospitalization rates also followed this trend, with 5.2% (n=30,648) of SMI patients being hospitalized compared to 3.7% (n=115,995) among non-SMI patients (OR=1.41, p = 0.007). Moreover, SMI patients had lower vaccination rates of 45.6% (n=268,888) versus 58.9% (n=1,844,261) among non-SMI patients (OR=0.77, p = 0.019).

Conclusions

In conclusion, our findings reveal significant disparities in healthcare service utilization between individuals with Serious Mental Illness (SMI) and those without. Notably, the SMI cohort experienced greater disruptions in service continuity, with a more pronounced decline in both outpatient and inpatient visits. Furthermore, the types of disorders diagnosed among this group also saw a shift, emphasizing the need for specialized care and attention during times of crisis. The higher rates of COVID-19 infection and hospitalization among SMI patients compared to non-SMI patients underscore the urgency of targeted public health interventions for this vulnerable group. The lower vaccination rates in the SMI cohort highlight another layer of healthcare disparity that needs to be urgently addressed. These findings suggest that the pandemic has amplified pre-existing inequalities in healthcare access and outcomes for individuals with SMI, calling for immediate, evidence-based interventions to mitigate these effects and ensure equitable healthcare service provision.