Comparison of Two Waves of COVID-19 in Critically Ill Patients: A Retrospective Observational Study

Abstract

Background. The SARS-CoV-2 virus caused the global COVID-19 pandemic, with waxing and waning course. This study was conducted to compare outcomes in the first two waves, in mechanically ventilated patients. Methods. This retrospective observational study included all mechanically ventilated COVID-19 patients above 18 years of age, between March 2020 and January 2021. Patients were grouped into first wave from March 2020 to July 2020, and second wave from August 2020 to January 2021. Outcome measures were mortality, the development of acute kidney injury (AKI), and need for renal replacement therapy (RRT). Univariate and multivariate cox regression analysis were used to delineate risk factors for the outcome measures. Results. A total of 426 patients, 285 in the first wave and 185 in the second wave, were included. The incidence of AKI was significantly lower in the second wave (72% vs. 63%; p = 0.04 ). There was no significant difference in mortality (70% vs. 63%; p = 0.16 ) and need for RRT (36% vs. 30%; p = 0.1 ). Risk factors for mortality were increasing age and AKI in both waves, and chronic kidney disease (CKD) (adj. HR 1.7; 95% CI 1.02–2.68; p = 0.04 ) in the second wave. Risk factors for AKI were CKD in both the waves, while it was diabetes (adj. HR 1.4; 95% CI 1.02–1.95; p = 0.04 ) and increasing age in the first wave. Remdesivir (adj. HR 0.5; 95% CI 0.3–0.7; p < 0.01 ) decreased the risk of AKI, and convalescent plasma (adj. HR 0.5; 95% CI 0.3–0.9; p = 0.02 ) decreased the risk of mortality in the first wave, however, such benefit was not observed in the second wave. Conclusions. Our study shows a decrease in the incidence of AKI in critically ill patients, however, the reason for this decrease is still unknown. Studies comparing the waves of the pandemic would not only help in understanding disease evolution but also to develop tailored management strategies.

Kidney damage associated with COVID-19: from the acute to the chronic phase

“…Compared to others etiologies, the incidence and severity of COV-AKI appears to be higher than that reported in other settings such as community acquired pneumonia or sepsis [ 30 , 31 ], especially when considering the first wave [ 26 , 27 ]. Kolhe et al.…”

“…The incidence and severity of AKI (AKI requiring dialysis) decreased over time and across COVID-19 waves, with the first wave being more severe [ 2 , 26 , 27 ]. These results could indicate, on the one hand, a reduction in the virulence of SARS-CoV-2 due to multiple mutations and, on the other hand, the impact of vaccination in creating collective immunity beyond natural infection and the improvement in the management of COVID-19 with the introduction of corticosteroids in the treatment of severe cases of COVID-19 [ 28 , 29 ].…”

Manifestations of kidney involvement in COVID-19 patients and progression to chronic kidney disease

“…Some authors, including ourselves, believe that the occurrence of proteinuria and hematuria in a COVID-19 patient are independent predictors of the development of the critical stage of the disease [6,13,20]. Similarly, literature data also indicate that AKI has been diagnosed in patients with COVID-19 more frequently than cardiovascular (23%) and liver (23%) diseases [11][12][13][14]21]. Of the patients who developed AKI due to coronavirus infection, one in four patients required continuous hemodialysis, and 12 (80%) patients died within the first week of admission [2,5,9,22].…”

“…It has previously been established that AKI is a predictor of poor prognosis in hospitalized patients with COVID-19 [6,9,11]. The high prevalence of AKI in the severe COVID-19 group [1,3,12] and the increased mortality risk in patients with AKI [4,13,14] highlight the need to further explore predictors of kidney damage in this population. Additionally, most studies have investigated the prognosis without considering the timing of kidney failure onset.…”

Outcomes of COVID-19 patients with acute kidney injury and longitudinal analysis of laboratory markers during the hospital stay: A multi-center retrospective cohort experience from Pakistan

“…The first of these studies showed the incidence of AKI being significantly lower in the second wave. [ 36 ] But the Italian cohort showed similar rates of AKI in both waves of COVID-19. [ 37 ] While, we reported previously in our comparison of waves that similar rises in serum urea levels were observed during both waves, while peak levels were attained early in the second wave, despite creatinine was deranged equally in both waves.…”