Here is the design of a clinical trial:

Official Title: A Multicentric Survey on Patients Over 60 Admitted to Intensive Care for Severe Forms of COVID Infection: Search for Prognostic Criteria Associated With Survival

Included conditions:
- COVID-19 Disease, Severe Form

Study Armgroups:

Interventions:
- {'type': 'OTHER', 'name': 'Group1', 'description': "* Comorbidities (CIRS-G scale),\n* Functional status of the patient with\n\n  * Clinical frailty scale (1 month before infection)\n  * ADL score (1 month before infection)\n* Biological data\n\n  * Blood group\n  * TP, D-dimers, CRP, creatinine level at the patient's entry, triglyceridemia, fibrinogen, ferritin\n  * Parameters derived from the platelet formula count on D1 of the start of intensive care (lymphocytes, neutrophils, platelets, average platelet volume, red blood cell distribution index), SYSMEX data (IG: Immature granulocytes; HFLC: high fluorescent lymphocyte count)\n* Resuscitation outcomes\n\n  * LDH rate at the start of intensive care\n  * PaO2 / FiO2 ratio at the start of intensive care\n  * IGSII / SASPII score (simplified acute physiology score) on D1 of the start of intensive care\n  * SOFA score (sepsis-related organ failure assessment): a posteriori estimate based on IGSII / SASPII\n  * Delay between the appearance of the first signs of infection and admission to intensive care"}

Primary Outcomes:
- {'measure': 'Evaluation of the impact of age on mortality at 30 days after admission to intensive care', 'description': "First hypothesis: considering a single analysis variable (age), with expected mortality of 30% in patients under 70, and 70% in patients over 70 (with 40% of patients over 70), a total of 130 patients is necessary to show a statistically significant difference between these two groups with a power of 90% (bilateral alpha risk test of 5%). Since the multivariate analysis considers the integration of several factors, considering 15 factors, hoping for a coefficient of determination of 0.5 of the model, to achieve an optimism of less than 10%, it will be necessary to include 185 patients.\n\nAfter the publication of data on mortality in ICU in Lombardy region, Italy in April 2020, it was considered that a stopping of the trial at 185 patients would impair its statistical power and induce a potential risk of patients' selection bias. As a consequence the scientific committee decided that all the patients admitted to ICU until May 7th would be proposed the study.", 'timeFrame': '30 days after resuscitation admission'}

Please estimate the sample size based on the assumption: 
Power of 90%, bilateral alpha risk test of 5%, considering 15 factors with a coefficient of determination of 0.5 to achieve an optimism of less than 10%.
Sample size calculation
        To assess the effect of age on mortality in ICU, it is planned to compare mortality between patients under 70 years old and over 70 years old. Based on the results from a Chinese retrospective study,1 the hypothesis of the Senior-COVID-Rea study was the following: considering a single analysis variable (age), and an expected mortality of 30% for patients under 70 years old and 70% for patients over 70 years old (patients over 70 years old representing 40% of the study population), it will be necessary to include a total of 130 patients to show a statistically significant difference between these two groups with a power of 90% (bilateral alpha risk test of 5%). Since the analysis considers the integration of several factors, considering 15 factors, hoping for a coefficient of determination of 0.5 of the model, to achieve an optimism of less than 10%, it will be necessary to include 185 patients (criterion 1 of Riley et al
28).
        After the publication of data on mortality in ICU from Lombardy, Italy, in April 2020,2 it was considered that closing the inclusion process after 185 inclusions would impair the statistical power of the study and induce a potential patient selection bias. As a consequence, the scientific committee decided on 7 May 2020 that all the patients admitted to ICU before that dateâthat corresponded to the end of the first COVID-19 wave in Franceâwere eligible and proposed no limitation in terms of number of inclusions for this study. This sample size calculation was modified on Clinicaltrials.gov site accordingly (28 July 2020).