Analysis of trimodal pattern of mortality among hospitalized COVID-19 patients- Lessons from tertiary care hospital

Abstract

Background and aims: Many patients with COVID-19 become critically ill and requireICU admission. Risk factors associated with mortality have been studied, but this study provides insight regarding disease progression and hence help to plan rescue strategies to improve patient outcome.

Material and methods: This retrospective, observational study included all patients with diagnosis of COVID-19 from March1 to June30,2021 who died in hospital.

Results: During the study period, 1600 patients were admitted, with 1138 (71%) needing ICU care. There were 346 (21.6%) deaths, distributed as 15.8%(n = 55) within 48h of admission, 46.2%(n = 160) in next 10 days, and 37.8%(n = 131) thereafter. This trimodal mortality pattern of distribution was similar to polytrauma patients. Patients were divided into categories according to time duration from admission to death. In our cohort, 235 (14.7%) patients required mechanical ventilation, with a mortality of 85.4%(n = 201). Tachypnea was significantly (P < 0.001) associated with death at all times; however, hypotension was associated with early death and low oxygen saturation with poor outcome upto 10 days (P < 0.001). Refractory hypoxia was cause of death in all three groups, while other causes in group II were AKI (28%), sepsis (18%), and MODS (10%). Group III patients had different causes of mortality, including barotrauma (9%), pulmonary thromboembolism (8%), refractory hypercarbia (12%), MODS (13%), AKI (10%), sepsis (7%), and cardiac events (6%).

Conclusion: While physiological dearrangements are associated with rapid progression and early death, complications related to hyper-coagulable state, lung injury, and organ failure lead to death later. Providing quality care to a high volume of patients is a challenge for all, but posthoc analysis such as air crash investigation can help find out potential areas of improvement and contribute to better outcomes and mortality reduction.

Keywords: Causes of mortality; COVID-19; mortality; ordinal scale; trimodal peak.

Figure 1

Distribution of mortality with time. The graph shows the number of deaths each day among 346 expired patients during the second wave of COVID-19. The mortality trends show a trimodal distribution with 16% of deaths occurring within 2 days of admission, 46% within 10 days, and 38% later on

Figure 2

Graphical representation of patients in each group according to time mortality that were on ventilation at admission, needed ventilation later on, died within 24h of ventilation, or had DNR/DNI orders in place (limitation:~16% of missing data regarding details of ventilation)

Figure 3

Distribution of patients according to the WHO ordinal scale. Note- WHO ordinal scale: 0-Uninfected; 1,2-Ambulatory; 3-Hospitalized, no oxygen therapy; 4-Hospitalized, oxygen therapy by mask or nasal prongs; 5-Hospitalized, severe disease, noninvasive ventilation, or high-flow oxygen; 6-Intubation and mechanical ventilation; 7-Ventilation and additional organ support (vasopressors, renal replacement therapy, or ECMO). We divided category 5 into 5a-only oxygen requirement with no organ support, 5b-oxygen requirement and additional organ support. Y-axis represents the total number of patients who died in hospital (A) group II, n = 157 (B) group III, n = 131. The arrows represent the median time of adverse events leading to death in this group of patients

Figure 4

Comparison of causes of death in three groups according to time since hospital admission