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ORIGINAL ARTICLE
Year : 2021  |  Volume : 11  |  Issue : 2  |  Page : 96-100

Sequential organ failure assessment score for predicting outcome of severely ill obstetric patients admitted to intensive care unit


1 Department of Anaesthesiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences Lucknow, Sarojini Naidu Medical College, Agra, Uttar Pradesh, India
2 Department of Microbiology , Sanjay Gandhi Post Graduate Institute of Medical Sciences Lucknow, Sarojini Naidu Medical College, Agra, Uttar Pradesh, India
3 Department of Anaesthesiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Date of Submission16-Feb-2021
Date of Acceptance13-Apr-2021
Date of Web Publication01-Oct-2021

Correspondence Address:
Dr. Ashish K Kannaujia
Department of Anaesthesiology, A Block, First Floor, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JOACC.JOACC_15_21

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  Abstract 


Background and Aim: Severe maternal illness is a life-threatening condition for pregnant women and often requires admission into the ICU. The aim was to evaluate the performance of maximum sequential organ failure assessment (SOFA) score to predict the outcome of patients admitted to ICU. Material and Methods: This prospective study was done on 121 consecutive women with severe obstetric illness admitted to the ICU during one year. Basic demographic, obstetrical data, indication of admission to ICU and interventions done were noted. SOFA score was evaluated according to the worst score for each of its six components every 24 hr till discharge or death in ICU. The receiver-operator characteristic (ROC) curve was constructed to predict the outcome of ICU. For analysis, patients were categorized as survivors and non-survivors. Results: Out of 121 patients admitted, 65 survived and 56 died with mortality rate of 45.9%. There were no differences among survivor and non-survivor patients regarding demographic data, obstetrical data and interventions done, but anaemia and inadequate ante natal care was more common in non survivors. ICU utilisation rate of obstetric patients was 1.9%. Most patients were admitted due to obstetric causes (87.6%), mainly for hypertensive disorders (46%) and were post caesarean (84.29%). Total maximum SOFA scores were higher in non-survivors than in survivors (14.09 ± 5.53 vs 7.47 ± 4.58, P < 0.001). Area under curve (AUC) for SOFA score was 0.859, standard error 0.035, P < 0.001, showing good discriminatory power for predicting mortality in ICU. Conclusion: SOFA score is an effective tool to predict outcome of severely ill obstetric patients admitted to ICU.

Keywords: Maternal outcome, severe maternal illness, SOFA score


How to cite this article:
Srivastava U, Dwivedi Y, Verma S, Kannaujia AK, Ambasta S, Lalramthara I. Sequential organ failure assessment score for predicting outcome of severely ill obstetric patients admitted to intensive care unit. J Obstet Anaesth Crit Care 2021;11:96-100

How to cite this URL:
Srivastava U, Dwivedi Y, Verma S, Kannaujia AK, Ambasta S, Lalramthara I. Sequential organ failure assessment score for predicting outcome of severely ill obstetric patients admitted to intensive care unit. J Obstet Anaesth Crit Care [serial online] 2021 [cited 2021 Dec 9];11:96-100. Available from: https://www.joacc.com/text.asp?2021/11/2/96/327401




  Introduction Top


Majority of the women have normal course of pregnancy, labour and delivery but a small proportion of women develop severe complications. This may be due to aggravation of a pre-existing medical illness or complexities of pregnancy itself or delivery, leading to severe maternal illness. Severe maternal illness is defined as a life-threatening condition in pregnant or recently delivered woman. The women either exhibit a rapid worsening of illness and die or narrowly miss death (maternal near miss). However, for each woman who dies, many more women experience life-threatening complications. Major obstetric haemorrhage, hypertensive disorders of pregnancy and sepsis are the leading conditions accounting for severe maternal illness and death across the world.[1]

Varying degrees of organ dysfunction or failure are part of the pathophysiologic process of severe maternal illness.[2],[3] Determination of its incidence, character and prediction of outcome is helpful to better anticipate and possibly prevent the occurrence by timely management.[4],[5],[6],[7] Identifying criteria and scoring systems may help in evaluating the severity of the illness and predicting its outcome.

Majority of the currently available prediction methods such as simplified acute physiology score (SAPS), mortality probability model (MPM), acute physiology and chronic health evaluation (APACHE), etc., calculate the prediction from findings taken within 24 hours of ICU stay and miss many factors that can affect the patient's outcome during the entire period of the ICU stay. Sequential Organ Failure Assessment (SOFA) scoring system can assess organ dysfunction or failure over the time.[8] It allows for both the number and severity of organ dysfunction in six organ systems (respiratory, circulatory, coagulation, hepatic, renal and neurologic) and the score can measure individual or aggregate or total organ dysfunction or failure[4],[9] Although the scoring systems were developed to quantify organ dysfunction, they have been used to predict the outcome of critically ill general[9] and obstetric patients[2],[4],[5],[10]. SOFA score has been widely used in western world but there are limited studies from developing countries[6],[11] that evaluated SOFA scores for quantifying and predicting the outcome of severely ill obstetric patients admitted in ICU.

The aim of this study is to evaluate the utility of SOFA score to predict the outcome (death or discharge from ICU) of women with severe maternal illness admitted to ICU (primary outcome). The secondary outcome was to determine the clinical profile and indications for admission to ICU.


  Materials and Methods Top


This prospective, observational, cohort study was done during a one-year period in a 780-bedded tertiary care university affiliated government hospital. We have a ten-bedded multidisciplinary ICU caring for a variety of patients referred from medical (except cardiac patients), surgical and obstetric specialities. The study was done after getting approval from the Institutional Review Board and clearance from Ethical Committee. Being a tertiary care hospital (with a catchment area with a population over 3.5 million), many obstetric patients in critical condition, some following operative delivery complications, are referred to the obstetric unit and thereafter to our ICU.

The study recruited 121 women aged 18 years or more between 28 weeks of gestation and up to six weeks post-partum who were referred to ICU from the obstetric unit of our hospital with severe obstetrical or non-obstetrical complications and who stayed for more than 48 hours in ICU.

All data were collected prospectively on a pre-formed excel sheet devised for these patients. Data included demographic and other characteristics including socio-economic status, obstetrical data (gestational age, parity, level of ante-natal care, mode of delivery), medical history, level of anaemia, indication for admission to ICU, therapeutic interventions done in ICU (such as mechanical ventilation), length of stay in ICU and variables to calculate SOFA score. The treatment and interventions of each patient was decided by the ICU in-charge and was not interfered at any stage.

SOFA scoring – All variables needed to calculate SOFA score[8] were recorded daily starting from the day of admission and thereafter every 24 hrs till discharge or death while in the ICU. The maximum SOFA score (0-4 points) was calculated daily for each of the six organ/system: respiratory, coagulation, hepatic, cardiovascular, neurologic and renal using the worst result of each variable. The aggregate score representing the total maximum SOFA score (0-24 points) was calculated in retrospect, summing the worst scores for each of the components during entire stay in ICU in accordance with study of Moreno et al. 1998. For the purpose of analysis, organ dysfunction was defined as a maximum score between ≥1 and ≤2 while a score of ≥3 was defined as organ failure.

Statistical analysis

For the purpose of analysis, the obstetrical patients admitted to ICU were categorized according to outcome, as survivors (who were discharged from ICU) or non-survivors (who died in the ICU). Chi square test (with Yates correction when applied) was used for categorical variables and one-way analysis of variance to assess continuous variables. The discriminatory power of total maximum SOFA score, that is, the ability of the scores to discriminate between patients who survive or who die, was evaluated using receiver operating characteristics (ROC) curve and the area under curve (AUC) was used to define discriminatory power of the scores with an AUC 1.0 considered perfect discrimination and 0.5 considered equal to chance.


  Results Top


During one-year period of study 121 severely ill obstetric patients were referred to our ICU representing 9.93% of all ICU admissions and 1.9% of all the deliveries conducted in our hospital in that period. There were 65 survivors and 56 non-survivors, with maternal mortality rate of 45.9%. Obstetric causes constituted for majority of admission (87.6%). 48% of admissions were because of hypertensive disorders of pregnancy. The basic demography and characteristics are listed in [Table 1]. There was no difference among two groups (survivor group and non-survivor group) regarding age, gestational age, cause of admission (obstetric or non-obstetric cause), socio-economic status, or time of admission (ante-partum or post-partum) but relatively more women were anaemic and had received inadequate ante-natal care in non-survivor group (P < 0.05). There was no difference among survivors and non-survivors in relation to duration of ICU stay and interventions required [Table 1].
Table 1: Demographic data and clinical profile of patients admitted to ICU

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[Figure 1] shows frequency distribution of total maximum SOFA scores in survivors and non-survivors. The mortality ranged between 7.7% in patients with maximum SOFA score of ≤2 to more than 93% in patients with maximum SOFA score of more than 18. Mean total maximum SOFA score was higher in non-survivors than in survivors [20.50 ± 1.84 vs 7.47 ± 4.58, P < 0.001, [Table 2]. Of all the patients admitted, 27 (23%) had organ dysfunction (SOFA score ≤2) and failure of one or more organ/system (SOFA score ≥3) occurred in 94 (76.85%) of patients. [Table 2 shows the of maximum SOFA scores (mean ± SD) of individual organ/systems in survivors and non-survivors. All the individual organ/system scores were significantly higher in non- survivors than in survivors (P < 0.001) except in coagulation (P = 0.078). Relation between number of organ failures to outcome is depicted in [Table 3]. The patients with failure of one organ (maximum SOFA score 3.16 ± 1.45) had mortality rate of 8.33% while patients with failure of all six organs (maximum SOFA score 20.50 ± 1.84) had a mortality rate of 92.86%.
Figure 1: Frequency distribution of maximum SOFA in survivors and non-survivors. Asterisks (*) present the relationship between maximum SOFA score and ICU mortality, with the logistic regression curve superimposed

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Table 2: Maximum SOFA Score (Mean±SD) for each organ/system in survivors and non-survivors

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Table 3: Number of organ failure (SOFA score ≥3) and outcome of ICU

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The ability of total maximum SOFA score was evaluated using ROC curve to predict ICU mortality. The total maximum SOFA score had an area under the curve (AUC) of 0.859, SE 0.035 (P < 0.001) with a cut off value of 10, sensitivity 96.6% and specificity 90.0%, showing good discriminatory power for predicting the mortality in ICU [Figure 2].
Figure 2: ROC Curve (AUC 0.859, SE 0.035) ROC analysis of total maximum sequential organ failure assessment (SOFA) score for Prediction of Mortality Rates (PMR) in ICU

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  Discussion Top


There was a predominance of post-partum (90.9%) admissions and the majority were admitted for obstetrical causes (87.6%). In this study, the most common mode of delivery was an emergency caesarean section (84%), a finding similar to previous studies.[10],[12],[13],[14],[15],[16] Among the obstetric cause, the complications of hypertensive disorders of pregnancy (48%) were most common[7],[10],[17],[18] followed by major obstetric haemorrhage (30.8%)[14],[15],[19],[20] and septicaemia (17.8%). There were no differences among survivors and non survivors with respect to age, socio economic status or parity, but non survivors received inadequate antenatal care[2] and were significantly anaemic.[14]

The ICU utilisation rate of 1.90% in the present study is well within the range reported in recent Indian studies of 0.14–2.9%.[6],[7],[14],[15],[18],[19] The obstetric patients formed 9.93% of all the ICU admissions in the current study. Total ICU admissions in the study period were 1219 and out of these 121 were obstetric patients. The published admission rate of obstetric patients in ICU is highly variable ranging between 1 and 10% of ICU admissions.[6],[7],[10],[11],[16],[17],[18],[19] This may be due to the location of the hospital, the number of ICU beds, hospital policy, financial reasons, drained population, etc.

Despite the similarity in the clinical profile of critically ill obstetric patients worldwide,[12] there remains a large disparity in maternal mortality among various countries, ranging between 2 and over 50%[4],[7],[10],[14],[15],[16],[17],[18],[19],[21],[22],[23] with higher rates in low- or middle-income countries. Some of the reasons may be poor socio-economic status,[24] multiparity, nutritional anaemia,[14] insufficient ante-natal care, complications related to pregnancy or delivery and lack of critical care facility.[16],[25] The maternal death rate (45.9%) in our study is higher than that reported in various other studies.[7],[21],[23],[25] But maternal mortality in our study is coinciding with that reported by Gupta et al.[14] and Tempe et al.[26] Our institute is a government hospital that acts as the largest referral centre in the region and very often patients are referred in a critical condition. Higher rates could be reflected in the fact that 17/56 patients who died were referred from peripheral hospitals, that were not having critical care facilities.[4],[17],[21],[25]

We evaluated the performance of maximum SOFA score to quantify the severity of organ failure in obstetric patients in the ICU. The scores were significantly higher in women who died than those who were discharged from ICU (14.09 ± 5.53 in non-survivors and 7.47 ± 4.58 in survivors, P < 0.001). Many previous authors[4],[5],[6],[11] reported higher SOFA scores in patients who died compared to those who survived.

The predictive ability of the total maximum score was evaluated using the ROC curve and the AUC was used to demonstrate the discriminatory power of scores. It demonstrated AUC of 0.859, SE 0.035, suggesting very good power to discriminate between patients who would survive or not survive (P < 0.001) from the illness in the ICU, a finding in agreement with previous reports.[4],[5],[6],[11] AUC of more than 0.7 has been related to good performance[14] and our value was well above 0.7.

Mean SOFA scores of each organ system were also significantly higher except that of coagulation, in the patients who died compared to those who survived showing a clear correlation between higher score and mortality. The same relation was evident when we limited the analysis to the number of organ failures; as the number of failing organs increased, the mortality also increased.[4],[5],[9],[11] Involvement of more than one organ occurred in 85% of patients, out of which 58.5% died. The phenomenon of organ failure or dysfunction occurs not in isolation but is usually interdependent. Multi-organ failure and high SOFA scores for any individual organ are associated with increased mortality,[2],[8],[23] a finding further validated in this study. In contrast to our results, more than one organ was involved only in 20–24% of patients in few studies.[4],[5] A potential explanation for the observed difference might be due to late referral to ICU when the patients were already in multi-organ failure.[16],[19]

Limitations: This study recognises certain limitations. The study involved data of only one year, hence the sample size was relatively small which might have resulted in the less precise estimation of accuracy of the SOFA score. We evaluated the relationship of the SOFA score to ICU outcome and not with all obstetric deaths in the hospital. It was a single centre study; therefore, the results cannot be extrapolated to a diverse obstetric population. But these data provide insight into the factors that are associated with maternal ICU admission, quantification of organ failure and prediction of the outcome of ICU.


  Conclusion Top


It is evident from this study that use of SOFA score had good prognostic power when applied to obstetric patients with severe illness admitted to ICU. The score is easy to calculate and requires easily available laboratory and other variables. Based on this, obstetricians can transfer the women with severe illness at early stage to appropriate referral centre. Being young and otherwise healthy, if these patients receive timely intervention in ICU then they have better chances of survival.

Acknowledgements

We acknowledge the help of Ms. Shreya Verma in statistical analysis Written and informed consent was taken.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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