INTRODUCTION:

Intensive care unit cater to patients with severe or life-threatening illnesses and injuries, which require constant care and close supervision. Prognostication of critically ill patients, in a systematic way, based on definite objective data is an integral part of the quality of care in ICU. An adequate scoring system should be able to define critically ill-patients, estimate prognosis, and set a benchmark for the maintenance of standards of care in the ICU.

A number of physiological based scoring systems have been developed over the years to achieve these goals. However, among many severity scoring systems, Acute physiology and chronic health Evaluation (APACHE) scoring systems provide an objective means of mortality prediction in ICU. Development of the original APACHE, began in 1978.¹ APACHE-I was proposed in the year 1981. It considered 34 routinely collected physiological measurements in the hospitals. Each of these measurements was assigned a weight according to the severity of derangement; higher the score more is the chance of death. However, this was found too complex as it included the large number of variables.

APACHE II scoring system developed by Knaus et al² in 1985 as a modification of the original APACHE score, consists of reduced acute physiology score (APS) variables from 34 to 12 with age points and chronic health points. Further, APACHE-III scoring system was developed between 1991 to 1998. The APACHE III scores vary between 0 and 299 points, including up to 252 points for the 18 physiological variables, up to 24 points for age, and up to 23 points for the chronic health status. APACHE IV scoring system was introduced in 2006 as an improved and updated model for predicting hospital mortality among critically ill patients and is the most recent version of the APACHE scoring system. This model included the new predictor variables like mechanical ventilation, thrombolysis, Pao2/fio2 ratio, impact of sedation on Glasgow Coma Scale, pre-ICU hospital length of stay, location prior to ICU admission and 116 disease specific subgroups in addition to the modifications introduced in the APACHE III.³

Even though newer scoring systems replaced APACHE II in many places, APACHE II continues to be used extensively because so much documentation are based on it. The most important difference is that all of the severity and diagnostic data have been collected early in the course of each hospital stay, within 24 hrs of ICU admission, rather than after hospital discharge.⁴

There are very few studies comparing the APACHE II and APACHE IV scoring systems in the ICU in an India setting. Thus, we designed a study to observe the performance of APACHE II and APACHE IV scoring system in our ICU. The aim of this study was to investigate the suitability of APACHE IV severity scores. The study also evaluates the usefulness of APACHE IV score as a single criterion of triage protocol for admission in ICU.

STATEMENT OF THE PROBLEM:

A Comparative Study between APACHE IV VS APACHE II Scoring System in Predicting the Clinical Outcomes of Patients in Intensive Care unit at Selected Hospitals, Chennai.

OBJECTIVES OF THE STUDY:

1. To predict the clinical outcome of ICU patients with APACHE IV and APACHE II scoring systems.

2. To compare APACHE IV scoring system and APACHE II scoring system in predicting the clinical outcome of ICU patients.

3. To find out the association between the selected background variables of the ICU patients and their predicted clinical outcomes.

METHODS AND MATERIALS:

A non-experimental descriptive approach and a comparative research design was adopted for achieving the objectives of the study. In this study, dependent variable was clinical outcome of the ICU patients such as actual observed mortality rate and length of stay of ICU patients, the independent variables were APACHE II and APACHE IV scoring system and the attribute variables were the demographic and clinical variables of the patients in intensive care unit. An extensive literature review and guidance by the experts formed the foundation for the development of the tool such as Demographic Variables Proforma, Clinical Variables Proforma, APACHE II and APACHE IV score to assess severity of the ICU patients. The content validity and the reliability of the tool were established. The present study was conducted among 100 ICU patients selected by purposive sampling technique at intensive care unit of Apollo Main Hospital, Greams Road in Chennai. After obtaining setting permission and participant’s consent the pilot study was conducted to ascertain the researchability and the feasibility of the study. The data for main study was collected from the selected samples, tabulated and analyzed using descriptive and inferential statistics.

RESULTS AND DISCUSSION:

Majority of the intensive care patients were aged >50 years (68%), male (70%), employed (63%), non-sedentary workers (62%), most of them were non-smokers (96%) and non-alcoholics (91%). 32% of the them were admitted due to neurological problems which was similar to the study population of Dabhi AS et al ⁵, and Varghese YE et al ⁶. The mean age of ICU patients was 57.55 ± 14, 9 years with the mean height of 162.2 ± 18.2 cm, mean weight of 70.3 ± 13.5 kg and mean BMI of 27.06 ± 5.04. Their mean length of stay in ICU was 7.03± 4.87 days and the mean ventilator days 1.75 ± 0.93 days. The mean APACHE II score was 12.68 ± 7.44 and mean APACHE IV score was 61.43± 22.91. The actual mortality rate was 18%. The estimated mortality rate by APACHE II score was 15.4% and by APACHE IV score was 19%.

Fig. 1. Correlation between APACHE II and APACHE IV Scores of Patients in Intensive Care Unit

Table 1. Area Under Curve for APACHE II and APACHE IV Scores

Test Result Variable(s)	Area	Std. Error^a	Asymptotic Sig.^b	Asymptotic 95% Confidence Interval
Test Result Variable(s)	Area	Std. Error^a	Asymptotic Sig.^b	Lower Bound	Upper Bound
Apache II	.965	.018	.000	.930	1.000
Apache IV	.760	.074	.001	.615	.905

The comparison between the mean scores of estimated mortality rate based on APACHE II and APACHE IV score of patients in intensive care unit denotes that there was no statistically significant difference (t= 1.674) at p<0.05 level. There was a significant weak correlation between actual length of stay and estimated length of stay based on APACHE IV score (r = 0.469) at p < 0.01 level. The fig 1 shows a strong positive correlation between APACHE II and APACHE IV Scores of Patients in Intensive Care Unit (r=0.74) at p<0.001 level. The above results demonstrate that there was not much variability between the two scores. This study results were supported by Varghese et al⁶ and Lee et al^7.

The discrimination of APACHE II as determined by area under curve (AUC) in present study was 0.965. This is similar to previously reported study conducted by Ayazoglu et al⁸, had AUC of 0.98 The AUC for APACHE IV in the present study was 0.768 (fiq 2 and table.1) indicating that a better discriminating ability by APACHE II compared to APACHE IV. It was observed from this study that the APACHE II model better predicted mortality than APACHE IV scoring system in our ICU. APACHE II had better calibration then APACHE IV^9.

There was no significant association between the selected background variables of ICU Patients such as age, sex, dietary intake, occupational status, nature of work, smoking, alcoholism, reason for admission, length of ICU stays and their mean APACHE- Scores. But there was a significant association between the mean APACHE score and attribute variables such as history of trauma (p<0.05) and No. of ventilator days (p=0.001).

CONCLUSION:

Both APACHE models have shown good performance in this study. However, APACHE II showed better calibration than APACHE IV through AUC curve. Larger multicenter validation studies with customization for the Indian ICU population are needed.

ACKNOWLEDGEMENT:

I would like all the research participants of this study and all who helped me directly and indirectly in the conduction of the study.

CONFLICT OF INTEREST:

No conflict of interest.

REFERENCES:

1. Relman, AS. Assessment of Medical practices, (editorial). N Engl J Med. 1980: 303:153-154.

2. Knaus WA, Draper EA, Wagner. APACHE II: a severity of disease classification system. Critical Care Medicine. 1985: 13(10) 818-29).

3. Nagar V S, Sajjan B, Chatterjee R & Para NM. The comparison of apache II and apache IV score to predict mortality in intensive care unit in a tertiary care hospital. Int J Res Med Sci. May 2019; 7(5):1598-1603 DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20191643

4. Wagner, D.P, Knaus, W.A & Draper. Statistical validation of a severity of illness measure. 1983: 73:878-884.

5. Dabhi AS, Khedekar SS, Mehalingam V. A prospective study of comparison of APACHE-IV and amp; SAPS-II scoring systems and calculation of standardised mortality rate in severe sepsis and septic shock patients. J Clin Diagn Res. 2014; 8(10):09-13.

6. Varghese YE, Kalaiselvan MS, Renuka MK, Arunkumar AS. Comparison of acute physiology and chronic health evaluation II (APACHE II) and acute physiology and chronic health evaluation IV (APACHE IV) severity of illness scoring systems, in a multidisciplinary ICU. J Anaesthesiol Clin Pharmacol. 2018; 33(2):248-53.

7. Lee H, Shon YJ, Kim H, Paik H, Park HP. Validation of the APACHE IV model and its comparison with the APACHE II, SAPS 3, and Korean SAPS 3 models for the prediction of hospital mortality in a Korean surgical intensive care unit. Korean J Anesthesiol. 2014; 67(2):115.

8. Ayazoglu TA. A comparison of APACHE II and APACHE IV scoring systems in predicting outcome in patients admitted with stroke to an intensive care unit. Anaesth Pain Intens Care. 2011; 15(1):7-12.

9. Zhu BP, Lemeshow S, Hosmer DW, Klar J, Avrunin J, Teres D. Factors affecting the performance of the models in the mortality probability model II system and strategies of customization: a simulation study. Crit Care Med. 1996; 24(1):57-63.

Received on 04.05.2021 Modified on 14.10.2021

Asian J. Nursing Education and Research. 2022; 12(2):170-172.

DOI: 10.52711/2349-2996.2022.00034