This is an observational study of COVID-19 positive patients admitted to an acute medical unit in a district general hospital (secondary care setting). The study describes the clinical characteristics of COVID-19 positive patients at presentation and investigates the risk factors associated with the outcome of survival or non-survival following hospital admission.
The mortality rate of our cohort of hospitalised COVID-19 positive patients was 40%. The age standardised mortality rate for COVID-19 in the Manchester area was reported as 55% in a similar time period by the Office of the National Statistics (8). We observed an increasing trend in mortality with advancing age which was in line with the national statistics (9). We did not observe any significant difference in outcome associated with variances in gender and ethnicity, but our studied population was predominantly Caucasian (87.4%). It has been reported that men are more at risk of death than women in a small cohort of COVID-19 positive patients in China involving 43 patients (10). We found that deaths were proportionately higher in care home residents, who are generally frailer than patients residing in their own homes. More than 50% of our cohort were frail and there was a higher percentage of deaths in frail individuals (63 vs 37%, p < 0.001). In our cohort 53% had a history of hypertension, 30% had diabetes, and 30% and 40% had at least one respiratory and cardiovascular disease, respectively. All these comorbidities were noted to be risk factors associated with poor outcomes in patients with COVID-19 infection in a meta-analysis of six studies with a total of 1558 patients (11). Although the presenting symptoms of shortness of breath and fever were similar between the groups, cough was less reported (35 vs 92, p < 0.001) in deceased patients, which supports the speculation that lack of a cough reflex can promote worse infection in elderly frail patients (11).
In the univariate logistic regression models several clinical characteristics were observed to show significant association with mortality. Older age showed a strong association with mortality in our cohort (OR 1.06; p < 0.001). Old age as a risk factor for mortality has been reported in a Chinese cohort with a median age of 67 years (12). An association of smoking with poor outcome (OR 1.75; P = 0.05) has been variably reported in other observational studies (13, 14). The risk of death within 15 days of hospital admission for COVID-19 infection was found to be higher in elderly patients with a history of smoking and underlying respiratory comorbidities (15).
In our study, diabetes mellitus and hypertension were not significant predictors of mortality. Both hypertension and diabetes have been shown to be associated with increased mortality in two separate meta-analyses (16, 17), but the mean age of most of the studies included in these meta-analyses was less than 60 years compared to the median age of our cohort (74 years). Also, our study showed that a lower BMI was a risk factor for mortality (OR: 0.90; p < 0.001), although the median BMI of survivors was in the normal (not obese) range. The association of obesity with severity of COVID-19 illness has been demonstrated in an observational study in China of 383 hospitalised patients, but the mean age of this cohort was less than 50 years (18). The influence of older age and frailty on poorer nutrition and reduced BMI could have overshadowed these observations in our cohort.
A history of cardiovascular disease ( OR 2.77; p < 0.001) and respiratory disease ( OR 1.88; p < 0.035) showed strong association with mortality in accordance with studies reported in other regions (19, 20). Although there has been much debate regarding the impact of RAASi treatment on poor outcome in COVID-19 infected patients, in our cohort, in which 25% were receiving RAASi treatment, a significant association was not observed (OR 0.61; P = 0.14) (21, 22). Among the laboratory variables a lower lymphocyte count (OR 0.59; p = 0.04) and a higher neutrophil: lymphocyte ratio (OR 1.05; p = 0.002) were strong predictors of mortality which is similar to findings in other observational studies (23). Dysregulation of the immune response resulting in reduced CD4 + helper T lymphocytes has been observed in patients with COVID-19 infection, more so in severe cases (24).
A lower eGFR on admission, and also acute kidney injury, proved to be strong and risk factors associated with mortality, and low eGFR was independently associated in a multivariate model ( OR 0.98; p = 0.01), an observation reported in a recent study on the influence of kidney disease on mortality in patients with COVID-19 (25).
In addition to eGFR, the multivariate models showed older age and frailty as strong and independent risk factors associated with mortality in COVID-19 positive patients. The influence of frailty (frailty score of 5 or more) upon mortality outweighed that of age in our cohort (multivariate model; OR:5.1; p < 0.001 vs OR:1.03; p = 0.03). Although several studies have reported age as a risk factor associated with mortality (26–28) the association of frailty status using the clinical frailty score has not been reported to be a predictor in COVID-19 patients to date.
In our centre, the escalation of care to mechanical ventilation for deteriorating COVID-19 patients was largely determined by the patient’s functional status using clinical frailty score and comorbid burden by a COVID team (doctors at consultant and senior registrar level in chest or general or intensive care medicine) in liaison with an intensive care specialist at the tertiary care referral centre. However, this approach was individualised on a case-by-case basis taking into account the severity of the clinical presentation. Both the patient and family members were fully involved in the decision-making process wherever possible.
This study could not include patients who were directly transferred to the intensive care unit for mechanical ventilation from the emergency department, thereby missing the opportunity to capture the characteristics and outcomes of patients who were critically sick at initial presentation. However, the epidemiology of this group of patients is well presented in the ICNARC data. The study is also limited by the single centre observational nature of the study methodology.