The study was performed at a public nursing home from March 15 to June 5, 2020, identifying all the COVID-19 confirmed patients. This reference nursing home was transformed into a COVID-19 center for the admission of institutionalized seniors considered probable or confirmed cases of COVID-19 from the same center or other nursing homes. To this end, a joint action strategy was settled with the other nursing homes in the country, establishing a referral circuit to support them in the event of an outbreak of COVID-19 disease in their institution. Within 72 hours of detecting the first COVID case, 35 residents were moved to a hotel to prevent further spread following medical criteria (residents with a low level of functional and cognitive dependence were transferred). In the different serological and PCR controls carried out, only three residents housed in the hotel had COVID-19 infection, and the mortality in this population was null.
The following data were recorded for all patients: age, sex, date of admission, mean stay, the origin of the patient, dementia stage, Barthel index, Charlson comorbidity index, previous flu vaccination, clinical presentation, laboratory results, treatment, RT-PCR for SARS-CoV-2, hospital referral, mortality rate, and case fatality rate.
Four categories of the patient’s origin were defined: the reference nursing home, other nursing homes, home, or hotel.
Dementia was measured by the Global Deterioration Scale (GDS), developed by Dr. Reisberg13, which consists of seven stages. 1: no cognitive decline, 2: very mild cognitive decline, 3: mild cognitive decline, 4: moderate cognitive decline, 5: moderately severe cognitive decline, 6: moderately severe decline, 7: very severe cognitive decline.
Barthel index14 is an ordinal scale of functional capacity used to measure performance in daily living activities, with values ranging from 0 (totally dependent) to 100 (totally independent). Proposed guidelines for interpreting Barthel index are: 0-15: totally dependent, 20-35: very dependent, 40-55: partially dependent, 60-75: minimally dependent, 80-100: totally independent15.
Underlying diseases were considered as the presence of comorbid illness with the age-adjusted Charlson comorbidity index16, which predicts ten-year survival in patients with multiple comorbidities.
Patients were grouped into three clinical categories: asymptomatic, respiratory symptoms (rhinitis, pharyngitis, cough, expectoration, and dyspnea) and digestive symptoms (diarrhea). Fever was defined as an axillary temperature of at least 37.5°C.
An analytical control was carried out, at least, on the admission and the discharge, recording the presence of lymphocytopenia, anemia, and or thrombocytopenia. Inflammation markers such as CRP, Ferritin, Dimer D, LDH, and troponin were also collected. Lymphocytopenia was defined as a total lymphocyte count of less than 1.0 × 109/L (1000/μL) and thrombocytopenia as a platelet count of less than 150 × 103 per μL. The diagnosis of anemia in men was based on a hemoglobin of less than 13 to 14 g/dL; in women, less than 12 to 13 g/dL.
As for the treatment, five categories were defined: patients who received hydroxychloroquine and azithromycin, only hydroxychloroquine, hydroxychloroquine plus another antibiotic, beta-lactam, or quinolone antibiotics, and no treatment.
We also recorded the percentage of patients with two consecutive (48 hours apart) negative molecular detection results for SARS-CoV-2 from a nasopharyngeal swab after 14 days of treatment with hydroxychloroquine and azithromycin.
Patients whose symptoms resolved and who had two consecutive (48 hours apart) RT-PCR for SARS-CoV-2 negative were considered successfully treated and cured17.
Four categories of discharge destination were defined: reference nursing home in non-COVID areas, other nursing homes, home, or death.
The mortality rate associated with COVID-19 in the center was considered as the death rate in the reference nursing home population.
The case fatality rate in the reference nursing center is the proportion of deaths from a COVID-19 disease compared to the total number of people diagnosed with the disease admitted in the center.
A statistical study has been carried out to identify risk factors for mortality in patients with COVID 19. Bivariate tests have been performed between the qualitative and quantitative variables and the successfully treated variable COVID (yes / no). A chi-squared test was used for categorical variables and the t-test/Mann-Whitney test for quantitative variables. Additional bivariate analyses were performed to compare subject characteristics between treatment groups, in order to identify possible confounders. Variables with a p-value lower than 0.05 were included in a multivariate logistic regression model18 to identify independent predictors of mortality. The final model was obtained after removing all non-statistically significant variables (backward selection procedure). Furthermore, a second multivariate regression model was adjusted, including only baseline variables to obtain a score to predict mortality independently of the effect of pharmacological treatment. ROC curves have been obtained to evaluate the fit of the models, and the AUC has been calculated. The best cut-off point has been determined, and sensitivity and specified values have been obtained. Statistical analyses were performed with the SAS system version 9.4 (SAS Institute Inc., Cary, North Carolina, USA). The statistical significance level was set at 0.05.
The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request.