Trends in Illness Severity, Hospitalization, and Mortality for Community-Onset Pneumonia at 118 US Veterans Affairs Medical Centers

Abstract

Background Deaths from pneumonia were decreasing globally prior to the COVID-19 pandemic, but it is unclear whether this was due to changes in patient populations, illness severity, diagnosis, hospitalization thresholds, or treatment. Using clinical data from the electronic health record among a national cohort of patients initially diagnosed with pneumonia, we examined temporal trends in severity of illness, hospitalization, and short- and long-term deaths. Design Retrospective cohort Participants All patients >18 years presenting to emergency departments (EDs) at 118 VA Medical Centers between 1/1/2006 and 12/31/2016 with an initial clinical diagnosis of pneumonia and confirmed by chest imaging report. Exposures Year of encounter. Main Measures Hospitalization and 30-day and 90-day mortality. Illness severity was defined as the probability of each outcome predicted by machine learning predictive models using age, sex, comorbidities, vital signs, and laboratory data from encounters during years 2006–2007, and similar models trained on encounters from years 2015 to 2016. We estimated the changes in hospitalizations and 30-day and 90-day mortality between the first and the last 2 years of the study period accounted for by illness severity using time covariate decompositions with model estimates. Results Among 196,899 encounters across the study period, hospitalization decreased from 71 to 63%, 30-day mortality 10 to 7%, 90-day mortality 16 to 12%, and 1-year mortality 29 to 24%. Comorbidity risk increased, but illness severity decreased. Decreases in illness severity accounted for 21–31% of the decrease in hospitalizations, and 45–47%, 32–24%, and 17–19% of the decrease in 30-day, 90-day, and 1-year mortality. Findings were similar among underrepresented patients and those with only hospital discharge diagnosis codes. Conclusions Outcomes for community-onset pneumonia have improved across the VA healthcare system after accounting for illness severity, despite an increase in cases and comorbidity burden. Supplementary Information The online version contains supplementary material available at 10.1007/s11606-022-07413-8.

Hospital admission decisions for older Veterans with community‐onset pneumonia: An analysis of 118 U.S. Veterans Affairs Medical Centers

“…We previously found a decrease in hospitalizations that was not explained by lower illness severity and was also accompanied by lower 7‐day readmissions and mortality 6 . Provider and patients may be shifting toward outpatient management of pneumonia, possibly motivated by quantitative assessments of illness severity, 47 an increase in out‐of‐hospital care support systems, 48,49 or changes in inpatient capacity 50 .…”

“…46 We previously found a decrease in hospitalizations that was not explained by lower illness severity and was also accompanied by lower 7-day readmissions and mortality. 6 Provider and patients may be shifting toward outpatient management of pneumonia, possibly motivated by quantitative assessments of illness severity, 47 an increase in out-of-hospital care support systems, 48,49 or changes in inpatient capacity. 50 Seven-day secondary admissions were stable overall, suggesting that this trend toward outpatient management is safe and possibly beneficial compared to hospitalization for many patients with pneumonia.…”

“…For the older patient, the consequences of pneumonia are even greater, due to both increased vulnerability to infection and end‐organ complications 2–4 as well as complications of treatment, including hospitalization 5 . We previously identified reductions in hospitalizations and mortality for Veterans seeking care at Veterans Affairs (VA) emergency departments (EDs), but younger Veterans had greater reductions than older patients 6 . The purpose of this study was to use clinical data from the electronic health record (EHR) to: Describe the risk of hospitalization for older compared to younger patients in a cohort of Veterans presenting with pneumonia to 118 VA EDs. Examine facility variation in hospitalization risk and associations between facility‐level hospitalization and mortality among older Veterans compared to younger Veterans. …”

“…5 We previously identified reductions in hospitalizations and mortality for Veterans seeking care at Veterans Affairs (VA) emergency departments (EDs), but younger Veterans had greater reductions than older patients. 6 The purpose of this study was to use clinical data from the electronic health record (EHR) to:…”

Variance estimation in pseudo-expected estimating equations for missing data

“…An example is electronic health records, which contain a significant frequency of incomplete information (4.3-86%) about patients in real-world settings. Electronic health records are increasingly used in large, observational studies to produce real-world study of outcomes (Dixon and others, 2020) and develop predictive models for use in clinical applications (Jones and others, 2022). Discarding observations with missing values can seriously threaten the validity of statistical inference and prediction based on such datasets, and can also lead to loss of statistical efficiency (Little and Rubin, 2002;Carpenter and Kenward, 2012).…”