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Year : 2022  |  Volume : 18  |  Issue : 1  |  Page : 3-8

Study the co-relation between SpO2 and radiological and biochemical markers with the severity and outcome in geriatric Covid-19 patients

1 Assistant Professor Geriatrics, Chengalpattu Medical College, Tamil Nadu, India
2 Dean Chengalpattu Medical College, Tamil Nadu, India
3 Associate Professor, General Medicine, Chengalpattu Medical College, Tamil Nadu, India
4 Associate Professor, Community Medicine, Chengalpattu Medical College, Tamil Nadu, India
5 Post Graduate, General Medicine, Chengalpattu Medical College, Tamil Nadu, India

Date of Submission21-Sep-2021
Date of Acceptance26-Nov-2021
Date of Web Publication21-Apr-2022

Correspondence Address:
Dr. Selvanathan Sumathi
Asst. Professor of Geriatrics, Chengalpattu Medical College, Chengalpattu, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiag.jiag_26_21

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Background: Pandemics are natural calamities, which humans have been encountering since time im-memorial. The world has witnessed and endured several pandemics like from Justinian Plague to Spanish Flu. The 21st century has already witnessed three major pandemics like Severe Acute Respiratory Syndrome in 2002, Middle East Respiratory syndrome in 2012 and at present COVID-19. The first case of COVID-19 was reported in Wuhan, Hubein Province in Dec 2019. The first case of COVID-19 was reported in Kerala on 30th January 2020. COVID-19 virus is a single stranded RNA Virus and resembles SARS -2 virus and hence the name SARS -COV 2. There has been a report of around 34 million cases with 1 million deaths. Majority of the deaths occur in the elderly population as they have immunosenescence and multiple comorbidities. Hence a study aiming at analysis of correlation between SpO2, radiological and biochemical markers is essential in management of COVID 19 in elderly. Aims & Objectives: To study the correlation between SpO2 and radiological features in X ray and CT Chest and biochemical markers with the severity and outcome in geriatric patients. Study Period: April 2020 to September 2020, Duration: 6 months. Study Centre: Chengalpattu Medical College, Tamilnadu. Inclusion Criteria: RT PCR positive Covid 19 patients more than 60 years of age. Exclusion Criteria: Covid 19 patients less than 60 years, RT PCR Negative patients. Materials and Methods: Retrospective analysis of records of 300 Covid 19 patients, aged more than 60 years hospitalized in Chengalpattu Medical College during April to September 2020 was done and biochemical parameters mentioned below were corelated with features in CXR and CT Chest RTPCR positive spo2 and analysis with severity of disease and outcome was done. Results and Discussion: On retrospective analysis of records of elderly Covid 19 patients, it was observed that the elderly could be graded as mild, moderate and severe based on clinical criteria. Radiological parameters co-relating in the same group classified as mild, moderate and severe could be derived and could be used for assessment of patients. Similarly, it was observed that the biochemical parameters of D- Dimer, C reactive protein, Neutrophil Lymphocyte Ratio correlated most significantly in that order with the clinical severity of disease and hence could be used as useful tools for assessment of severity of patients and the ranges corelating with severity could be derived. Conclusion: Analyzing SpO2, radiological features, biochemical parameters individually and in combination with clinical severity and outcome in elderly patients helps in deriving biochemical and radiological parameters to predict severity which in turn helps in a holistic approach and right management at the right time preventing or reducing mortality due to Covid 19 in the elderly.

Keywords: Biochemical markers, COVID-19, geriatrics, radiological features

How to cite this article:
Sumathi S, Ramalingam S, Ramasamy J, Banumathy G, Solomon S, Veer P. Study the co-relation between SpO2 and radiological and biochemical markers with the severity and outcome in geriatric Covid-19 patients. J Indian Acad Geriatr 2022;18:3-8

How to cite this URL:
Sumathi S, Ramalingam S, Ramasamy J, Banumathy G, Solomon S, Veer P. Study the co-relation between SpO2 and radiological and biochemical markers with the severity and outcome in geriatric Covid-19 patients. J Indian Acad Geriatr [serial online] 2022 [cited 2022 Jul 3];18:3-8. Available from: http://www.jiag.com/text.asp?2022/18/1/3/343682

  Introduction Top

Pandemics are natural calamities which humans have been encountering since time immemorial. The world has witnessed and endured several pandemics like from Justinian Plague to Spanish Flu. The 21st century has already witnessed three major pandemics like severe acute respiratory syndrome in 2002, Middle East respiratory syndrome in 2012, and at present COVID-19.

Coronaviruses represent a heterogenous cluster of large single-stranded RNA viruses, widely distributed among mammals and birds grouped under the family of Coronaviridae. As the number of new species increased, the genus was split into four genera, namely Alphacoronavirus, Betacoronavirus, Deltacoronavirus, and Gammacoronavirus in 2009.

At the end of the 2nd decade of the twenty-first century, the world has experienced an outbreak of novel coronavirus severe acute respiratory syndrome-related coronavirus (SARS-COV2), which started in Wuhan, in the Hubei province of China and spread to rest of the world. Horby and Heyden et al had reported a detIaled account of the covid outbreak in their article, “A novel Corona virus of Global Health concern”.[2] On January 30, 2020, the WHO declared the pandemic by this virus, which was taxonomically designated into the species of SARS-COV2 subgenus Sarbecovirus, genus Betacoronavirus. The terms SARS-COV2 and COVID-19 were coined for the disease caused by this virus.

Droplet and close contact have been recognized as the main routes of transmission.[5]

COVID-19 has a wide spectrum of presentation from asymptomatic course to mild dry cough, sneeze, fever, distressing myalgia to acute kidney injury, hyper-coagulable state with thrombotic complications, cardiac injury, progressive pneumonia with acute respiratory distress syndrome requiring ventilatory support and encephalitis.

COVID-19 is pro selective in its age group presentation with more persons getting infected in the 40–50 age group and the second age group elderly population 60 & above. Although the infectivity is high in the 40–50 years' age group, the mortality is high in the above 60 years' (elderly) age group.[9] Furthermore, the morbidity and post-COVID sequalae are extensive in the elderly and the disease has various presentations in the elderly.[11]

As the disease has a varied presentation, there is a need for the identification of lab parameters correlating with the severity and progression toward fatal forms of the illness. This helps in appropriate management of the cases by predicting which cases would worsen and which would fare well with a better outcome and design our management protocol. Hence, the study has been done to correlate biochemical markers, radiological findings, and SpO2 and respiratory rate with severity and outcome of disease in elderly patients.


To study the correlation between biochemical markers and radiological findings and spo2 and respiratory rate with the severity of disease among reverse transcription–polymerase chain reaction (RTPCR)-positive COVID-19 patients aged above 60 years.

  • Study period: April 2020 to September 2020
  • Study duration: 6 months.

Inclusion criteria

Patients above the age group of 60 years, RTPCR positive, admitted in Chengalpattu Medical College in the period between April and September 2020.

Exclusion criteria

Patients below the age group of 60 years and RTPCR negative.

  • Place of study: Chengalpattu Medical College
  • Study type: Retrospective study,

  Methodology and Observations Top

A retrospective analysis of the radiological features, biochemical markers, and SpO2 from data available in case sheets of 300 patients who were COVID-19 RTPCR positive and above the age of 60 years admitted in Chengalpattu medical college were done during the period of April 2020 to September 2020. The patients were classified as mild–moderate and severe based on the clinical parameters as in [Table 1].
Table 1: Depicting parameters used for clinical grading of patients

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The following biochemical parameters were analyzed in each case:

  1. Serum ferritin
  2. D Dimer values
  3. C reactive protein (CRP)
  4. Neutrophil–lymphocyte ratio
  5. Complete blood count
  6. Serum interleukin 6 levels.

These parameters were correlated with the clinical condition of the patient in terms of Spo2 and respiratory rate. Analysis of the biochemical parameters in the already classified mild, moderate, and severe group as per the clinical criteria was done, and the corresponding range of various biochemical parameters were studied.

This was again correlated with the chest X-ray (CXR) and CT chest of the same patients.

The chest X-ray findings were classified as follows:

  1. Normal
  2. Bilateral perihilar haze
  3. Bilateral multifocal consolidations
  4. Ground-glass opacity
  5. Nodular opacities.

A comparison of the biochemical factors as mentioned above with radiological features in CXR and CT chest and SpO2 and clinical parameters in the RT PCR-positive patients in the elderly in the mild, moderate, and severe group was done and the results were analyzed. The CT chest of the patients were assessed based on the CT severity scoring as proposed by Yang et al. and published in “Radiology” in March 2020.[13] It was created to help assess COVID-19 burden in SARS-COV2 patients in 2005. The score (CT-SS) is an adaptation of a method previously used during the SARS epidemic of 2005.[14]

This scale uses lung opacification as an equivalent for the extension of the disease in the lungs.

In this study, the 18 segments of both the lungs were divided into 20 regions, in which the posterior apical segment of the left upper lobe was subdivided into apical and posterior segmental regions, while the anteromedial basal segment of the left lower lobe was subdivided into anterior and medial basal segmental regions. Then, the lung opacities in all of the 20 lung regions were subjectively evaluated on chest CT. Each region was scored 0, 1, or 2 points depending on the parenchymal opacification involved: 0%, 1%–50%, or 51%–100%, respectively.

The overall CT severity score was defined as the sum of the points scored in each of the 20 lung segment regions, which ranges from 0 to 40 points. Opacity included both ground glassing and nodular consolidation.


Out the 300 elderly patients, classified clinically as mild, moderate, and severe cases whose CT scan chest were analyzed, 162 patient had lung involvement (<8%) which comes around 54% of the total RT PCR positive patients. This correlates with respiratory rate <24 and SpO2 more than 94%, corresponds to the mild group clinically. Similarly, 114 number of patients (n = 114), out of 300, which comes around 38 percent of total RT PCR positive, had lung involvement more than 8 and <24 out of 40 scoring corresponded to saturation between 90% and 94% and respiratory rate between 24 and 30 per minute. clinically. In the rest of no of patients, i.e., in 54 patients, (n = 54), which accounted for 18% of patients, the lung involvement was more than 24 out of 40 score. This corresponded to saturation less than 90% & RR more than 30 per minute clinically. So, based on above parameters, the radiological correlation in lung with clinical criteria in elderly RTPCR positive patients is as depicted in [Table 2].
Table 2: Correlation of radiological findings in computed tomography chest with clinical severity in study group

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The pie chart in [Figure 1] represents the severity grading in CT chest as mild–moderate and severe.
Figure 1: Pie chart depicting CT chest severity grading percentage

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[Figure 2] depicts the correlation of SPO2 and CT chest severity score in the category of mild, moderate, and severe patients taken.
Figure 2: Correlation of SpO2 and CT chest severity score in elderly COVID-19 patients

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On analyzing the chest X-ray patterns, the patients in the mild category based on the clinical criteria had perihilar haze or a normal chest roentgenogram. Patients in the moderate group had ground glassing or multifocal consolidation in less than half of lung field. Patients in the severe group had mostly B/L ground glassing resembling ARDS picture or multifocal consolidation in more than half of the lung fields.

On analyzing the biochemical parameters with the clinical severity, out of 300 patients, the following correlation, as depicted in [Table 3], was seen, between clinical severity of disease in terms of SPO2, respiratory rate as discussed already in the same mild, moderate, and severe group of patients.
Table 3: Depicting correlation of biochemical markers with clinical severity in study group

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[Figure 3] and [Figure 4] depict the correlation between biochemical parameters and Spo2 classifying them as mild, moderate, and severe.
Figure 3: Correlation of SPO2 and D-DIMER and NL ratio in elderly COVID-19 patients

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Figure 4: Depicting correlation between SpO2 and c reactive protein and serum ferritin in COVID-19 elderly patients

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In [Figure 3] and [Figure 4], X-axis represents the number of patients.

Similarly, clinical parameters of spo2, respiratory rate, and radiological findings in CT chest were analyzed in the survivors and nonsurvivors. Out of 300 patients, 254 patients were survivors and 46 patients were nonsurvivors. On analyzing the case records of the nonsurvivors, i.e., 46 patients, and comparing with the survivors, the nonsurvivors had SPO2 <45% on room air and on CT chest, the lung involvement was more than 34 out of 40 Yang's Score. Similarly, on analyzing the biochemical parameters in the 46 patients who made up 15.33% of the total 300 patients, the N: L ratio was >8.5, serum ferritin more than 7500 ng/ml, D Dimer >9 μg/ml, CRP >175/ml, and IL 6 >150 picogram/ml. This is depicted in [Table 4].
Table 4: Depicting biochemical, clinical, and radiological parameters between survivors and nonsurvivors

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  Results and Discussion Top

On retrospective analysis of the case records of 300 elderly patients, admitted between April and November 2020, the radiological, biochemical parameters and SPO2 with clinical severity and outcome, the following observations were made:

  • There exists a correlation between clinical status, as assessed by SPO2, respiratory rate and biochemical parameters in elderly RTPCR-positive COVID-19 patients.[8],[9],[10],[11],[12] Similar findings have been reported by Jayasri et al in their research publications on Boichemical Alterations in Covid 19 patients and on the clinical utility of lab parameters on assessing the severity of disease, and by Henry et al in their research article on haematological, biochemical and immune biomarker abnormalities associated with Coronavirus disease 2019.
  • The elderly patients could be graded as mild, moderate, and severe based on the Spo2 and biochemical parameters as depicted in [Table 5] and [Table 6]
  • On analyzing the radiological parameters, it was observed that there exists a correlation in severity, comparing the lung involvement in and the clinical status and biochemical parameters in the elderly patients. Similar findings have been observed by Caruso et al who based on their research have concluded that CT chest serves as an excellent complimentary method in early detection of Covid and also in assessing severity of covid and correlates in severity comparing with RT-PCR.[1] Osman AM and Abdrabou et al have reported the role of CT chest in predicting the severity of the disease and its role in management.[4]
  • On analyzing the radiological patterns of involvement, it was observed that patients having ground glassing, multifocal consolidation and full blown ARDS had poor prognosis when compared to subpleural opacity and subsegmental consolidations[3],[4],[5],[6],[7],[8],[9]
  • SpO2 on admission followed by neutrophil–lymphocyte ratio, D dimer, and CRP in the biochemical parameters were the parameters most consistent with CT severity grading and correlating with severity of disease in the elderly
  • It was also noted that in 10% of cases, there was clinical and radiological disparity, for example, the SpO2 was in the range of moderate clinical severity, but the radiological severity was in the severe range as derived. However, the same patients had biochemical markers in the severe range. But, in the rest, majority of 90% of the patients correlated in severity in terms of clinical and radiological parameters, underscoring the need to correlate various parameters
  • It was noted that, 8% of the patients had disparity in clinical and biochemical markers, as evidenced by admission SpO2 was in the mild range but the D-Dimer, NLR ratio and CRP were in the moderate range.[7] It was also noted that these patients had a subsequent fall in the SpO2 and worsened. This is an important finding, with respect to management aspect and further ascertains that a patient has to be assessed in all the 3 aspects of clinical, radiological, and biochemical parameters and emphasizes that it is not only the admission SpO2 that is important but the serial monitoring of SpO2 and its correlation with other parameters.
  • A CT chest severity score more than 34 out of 40 by Yangs classification score was associated with a high mortality rate in elderly Covid 19 patients compared to the non survivors who had a low CT chest severity score.[3]
  • A Abiochemical parameter of CRP more than 175, D Dimer > 9 microgram per ml, S ferritin >7500 ,IL6 >150 pcgm/ml and N:L Ratio more than 8.5 were biochemical markers associated with high mortality rate.
Table 5: Clinical severity of COVID-19 elderly patients

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Table 6: Biochemical severity grading derived from analysis

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  Conclusion Top

The COVID-19 pandemic has been an enigma and also a nightmare to the people of the world. The worst affected age group among all is the elderly. The elderly people have a high mortality due to COVID-19. The morbidity also is higher in the elderly population. There exists a correlation between clinical severity and biochemical markers and radiological parameters which can be used as predictors of severity of disease in elderly COVID-19 patients.[3],[4] A holistic approach is necessary to manage COVID-19 in the elderly comparing clinical parameters of Spo2, respiratory rate, and biochemical markers and radiological findings and predict the outcome and to act proactively with the right management at the right time to prevent death and to reduce the morbidity in the elderly.[6],[10]

Ethical committee approval

Ethical committee approval was obtained from Chengalpattu Medical College and the study was proceeded with.


We express our sincere thanks to the following personnel with the help of whom we have been able to bring this article: Dr. Muthukumaran MS, MCh. (Plastic Surgery), Dean, Chengalpattu Medical College (CMC and H); Prof. Ravi MD (Pathology), HOD Department of Pathology, CMC and H; Prof Sarasa MD (microbiology), HOD Department of Microbiology, CMC; Associate Prof. Vanitha MD (Radiology), CMC; and all staff of Medical Records Department, CMC and H.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Caruso D, Zerunian M, Polici M, Pucciarelli F, Polidori T, Rucci C, et al. Chest CT features of COVID -19 in Rome, Italy. Radiology 2020;296:E79-E85.  Back to cited text no. 1
Horby WC, Hayden FG, Gao GF. A novel Corona virus outbreak of global Health concern. Lancet 2020;395:470-3.  Back to cited text no. 2
Francone M, Lafrate F, Masci G, Coco S, Cilia F, Manganaro L, et al. Chest CT score in COVID 19 patients: Correlation with disease severity and short term prognosis. Eur Radiol 2020;31:4481-2.  Back to cited text no. 3
Osman AM, Abdrabou AM, Hashim RM, Khosa F, Yasin A. COVID-19 pandemic: CT chest in COVID-19 infection and prediction of patient's ICU needs. Egypt J Radiol Nucl Med 2021;52:135.  Back to cited text no. 4
Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, et al. Early transmission dynamics in Wuhan, China of novel corona virus -infected pneumonia. N Engl J Med 2020;382:1199-207.  Back to cited text no. 5
Kumar R, Singh V, Mohanty A, Bahurupi Y, Gupta PK. Corona health-care warriors in India: Knowledge, attitude, and practices during COVID-19 outbreak. J Educ Health Promot 2021;10:44.  Back to cited text no. 6
Gao Y, Li T, Han M, Li X, Wu D, Xu Y, et al. Diagnostic utility of clinical laboratory data determinations for patients with the severe COVID-19. J Med Virol 2020;92:791-6.  Back to cited text no. 7
Jayasri K, Pooja CH, Padmaja K, Prasad PE. Review on biochemical laterations in COVID 19 patients. Int J Clin Biochem Res 2020;7:307-11.  Back to cited text no. 8
Martins-Filho PR, Tavares CS, Santos VS. Factors associated with mortality in patients with COVID-19. A quantitative evidence synthesis of clinical and laboratory data. Eur J Intern Med 2020;76:97-9.  Back to cited text no. 9
Wasilewski PG, Mruk B, Mazur S, Półtorak-Szymczak G, Sklinda K, Walecki J. COVID-19 severity scoring systems in radiological imaging - a review. Pol J Radiol 2020;85:e361-8.  Back to cited text no. 10
Shahid Z, Kalyanamitra R, McClaffety B, Kepko D, Ramgobin D, Patel R, et al. COVID 19 and older adults: What we know. J Am Geriatr Soc 2020;68:926-9.  Back to cited text no. 11
Henry BM, de Oliveira MHS, Benoit S, Plebani M, Lippi G. Hematologic, biochemical and immune biomarker abnormalities associated with severe illness and mortality in coronavirus disease 2019 (COVID-19): a meta-analysis. Clin Chem Lab Med 2020;58:1021-8.  Back to cited text no. 12
Chest Ct Severity Score: An image tool for assessing Severe Covid-19. https://doi.org?10.1148/ryct.2020200047. [Last accessed on 2020 Mar 30].  Back to cited text no. 13
CORADS versus CT -SS scores in predicting severe Covid-19, Niveen E Zayeed Manar A, Samah. The Egyptian journal of Bronchology 15, Article 13 (2021) 11,14 Yang.  Back to cited text no. 14


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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