Utility of ariscat (Assess respiratory risk in surgical patients in catalonia) score in predicting postoperative pulmonary complications in patients undergoing elective/emergency surgery in a tertiary care Hospital in India

Vaseema Thabassum Shaik; RP Ilangho; K Bhaskaran

doi:10.4103/japt.japt_38_21

ORIGINAL ARTICLE

Year : 2021 | Volume : 4 | Issue : 3 | Page : 94-103

Utility of ariscat (Assess respiratory risk in surgical patients in catalonia) score in predicting postoperative pulmonary complications in patients undergoing elective/emergency surgery in a tertiary care Hospital in India

Vaseema Thabassum Shaik¹, RP Ilangho¹, K Bhaskaran²
¹ Department of Respiratory Medicine, Apollo Main Hospital, Chennai, Tamil Nadu, India
² Department of Cardiac Anaesthesia, Apollo Main Hospital, Chennai, Tamil Nadu, India

Date of Submission	22-Sep-2021
Date of Decision	27-Jan-2022
Date of Acceptance	07-Feb-2022
Date of Web Publication	12-May-2022

Correspondence Address:
Vaseema Thabassum Shaik
Department of Respiratory Medicine, Apollo Main Hospital, Chennai, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/japt.japt_38_21

Abstract

Introduction: Postoperative pulmonary complications (PPCs) account for a substantial proportion of risk related to surgery and anesthesia and are a major cause of postoperative morbidity, mortality and longer hospital stays. Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score is a risk prediction model developed for predicting PPCs. Objectives: To calculate the Sensitivity, Specificity of ARISCAT score in predicting postoperative pulmonary complications in patients undergoing Elective/Emergency surgery in a tertiary care hospital in India and to find out the incidence of postoperative pulmonary complications in various surgeries. Materials and Methods: Study Site: Apollo Main Hospital, Greams Road, Chennai. Study Design: Prospective Observational Study. Study Period: September 2018 to March 2019. Sample Size: Three hundred and thirty cases (330). Methodology: Patients undergoing non-Obstetric Elective or Emergency surgical procedure under general, neuraxial or plexus block anaesthesia were recruited through simple random sampling technique. After taking informed written consent, demographic details and clinical history were collected. Risk for post-operative pulmonary complications was assessed based on ARISCAT score. These patients were followed in the post-operative period till discharge to look for the following postoperative pulmonary complications -1. Respiratory failure 2. Pulmonary infection 3. Pleural effusion 4. Atelectasis 5. Pneumothorax 6. Bronchospasm 7. Aspiration pneumonitis. Results: The incidence of postoperative pulmonary complications in this study was 9.4%.The incidence of postoperative pulmonary complications in peripheral surgeries, upper abdominal and intrathoracic surgeries was 2.9 %, 14.1 % and 55.6 % respectively. The Sensitivity, Specificity, PPV and NPV of ARISCAT score were 83.9 %, 80.3 %, 30.6 % and 98 % respectively. Conclusion: ARISCAT score can be used as a routine screening tool for predicting the risk of developing PPCs.

Keywords: ARISCAT score, postoperative pulmonary complications, surgical patients

How to cite this article:
Shaik VT, Ilangho R P, Bhaskaran K. Utility of ariscat (Assess respiratory risk in surgical patients in catalonia) score in predicting postoperative pulmonary complications in patients undergoing elective/emergency surgery in a tertiary care Hospital in India. J Assoc Pulmonologist Tamilnadu 2021;4:94-103

How to cite this URL:
Shaik VT, Ilangho R P, Bhaskaran K. Utility of ariscat (Assess respiratory risk in surgical patients in catalonia) score in predicting postoperative pulmonary complications in patients undergoing elective/emergency surgery in a tertiary care Hospital in India. J Assoc Pulmonologist Tamilnadu [serial online] 2021 [cited 2023 May 29];4:94-103. Available from: https://www.japt.in//text.asp?2021/4/3/94/345082

Introduction

Postoperative pulmonary complications (PPCs) account for a substantial proportion of risk related to surgery and anesthesia and are a major cause of postoperative morbidity, mortality, and longer hospital stays.^[1],[2] A number of factors have been identified that are associated with the development of PPCs. They include preoperative factors (chronic lung disease, smoking, general state of health, age, obesity, nutritional status, and antecedent respiratory tract infection), intraoperative factors (the emergent nature of the procedure, type and duration of anesthesia, location of surgical site, and type of surgical incision), and postoperative factors (inadequate pain control and immobilization).^{[3],[4],[5],[6]} There are many studies, which have evaluated PPCs in various multispecialty surgical procedures. Many prediction models for PPCs have been published, most of which have limitations as a result of being developed from retrospective databases,^{[7],[8],[9],[10],[11]} focused on a single adverse outcome (e. g. pneumonia,^[9] unplanned re-intubation,^[10] acute lung injury (ALI)/acute respiratory distress syndrome (ARDS),^[11],[12] respiratory failure^[13]) or from a lack of inclusion of intraoperative risk factors.^[14] ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia) score is a risk prediction model, which was developed in 2010 from a prospective, multicenter trial, using EPCO definitions (European joint task force-perioperative clinical outcome definitions) for PPCs.^[14] It focuses on seven PPCs and includes three surgical risk factors. This study was done to find the utility of ARISCAT score in predicting PPCs in patients undergoing Elective/Emergency surgery in a tertiary care hospital in India.

Review of literature

Definition of postoperative pulmonary complication

Postoperative complication is defined as any undesirable, unintended, and direct result of an operation affecting the patient, which would not have occurred had the operation gone as well as could reasonably be hoped.^[15] Each year, more than 300 million patients undergo surgery worldwide.^[16],[17] Estimates of attributable mortality vary from 1% to 4%, however, more than one in five deaths occur in a small group of high-risk patients.^{[18],[19],[20],[21]} Even when complications are successfully treated, these are still associated with reduced long-term survival.^[22]

Classification of PPCs:^[23]

Grade I: Any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic, and radiological interventions. Allowed therapeutic regimens are drugs as antiemetics, antipyretics, analgesics, diuretics, electrolytes, and physiotherapy. This grade also includes wound infections opened at the bedside.

Grade II: Requiring pharmacological treatment with drugs other than such allowed for grade I complications. Blood transfusions and total parenteral nutrition are also included.

Grade III: Requiring surgical, endoscopic, or radiological intervention. Grade IIIa: Intervention not under general anesthesia. Grade IIIb: Intervention under general anesthesia.

Grade IV: Life-threatening complication (including CNS complications) requiring ICU management. Grade IVa: Single organ dysfunction (including dialysis). Grade IVb: Multiorgan dysfunction.

Grade V: Death of a patient.

After wound infections, PPCs are the second-most common type of postoperative complications with an incidence estimated to range from 2.0% to 5.6% 24,25. Studies done by Lawrence et al.,^[24] Khan et al.,^[25] Lawrence et al.^[26] have shown that pulmonary complications are more common than cardiac complications. Study done by Mazo et al.^[27] showed that postoperative respiratory failure is the most common PPC.^[27]

There is a wide spectrum of pulmonary complications which are as follows:^[28]

Atelectasis-resulting in postoperative hypoxemia
Pneumonia, bronchitis
Bronchospasm
Exacerbation of previous lung disease
Pulmonary collapse due to mucus plugging of the airways
Respiratory failure with ventilatory support >48 h
ALI including aspiration pneumonitis, transfusion-related ALI and ARDS
Pulmonary embolism.

The European joint task force published guidelines for European perioperative clinical outcome (EPCO) definitions. The EPCO-recommended definitions for PPCs are.^[29]

Respiratory infection

When a patient received antibiotics for a suspected respiratory infection and met at least one of the following criteria: new or changed sputum, new or changed lung opacities on a clinically indicated Chest X-ray, temperature >38.3°C, leukocyte count >12,000/mm³.

Respiratory failure

When postoperative PaO₂ (partial pressure of oxygen in the arterial blood) <60 mmHg on room air, a ratio of PaO2 to inspired oxygen fraction <300 or arterial oxyhemoglobin saturation measured with pulse oximetry <90% and requiring oxygen therapy.

Pleural effusion

Chest X-ray demonstrating blunting of the costophrenic angle, loss of the sharp silhouette of the ipsilateral hemidiaphragm in upright position, evidence of displacement of adjacent anatomical structures, or (in supine position) a hazy opacity in one hemithorax with preserved vascular shadows.

Atelectasis

Lung opacification with a shift of the mediastinum, hilum, or hemidiaphragm toward the affected area, and compensatory overinflation in the adjacent nonatelectatic lung.

Pneumothorax

Air in the pleural space with no vascular bed surrounding the visceral pleura.

Bronchospasm

Newly detected expiratory wheezing treated with bronchodilators.

Aspiration pneumonitis

Acute lung injury after the inhalation of regurgitated gastric contents.

The taskforce considered respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis to be the composite measures and defined pneumonia, ARDS, and pulmonary embolus as individual adverse outcomes.^[29]

Risk factors for developing PPCs can be divided into.^[14]

Patient factors
Procedure factors and
Laboratory testing.

Patient factors

Nonmodifiable patient related risk factors

Age, male sex, class American Society of Anesthesiologists class >= II, functional dependence, acute respiratory infection in 1 month, impaired cognition, impaired sensorium, cerebrovascular accident, malignancy, weight loss >10% in last 6 months, long-term steroid use, prolonged hospitalization.

Modifiable patient-related risk factors

Smoking, COPD, Asthma, Congestive Heart Failure, Obstructive Sleep apnea, Body Mass Index (BMI) <18.5 kg/m², BMI >40 kg/m², Hypertension, Chronic liver failure, Renal failure, Ascites, Diabetes mellitus, Gastro-esophageal reflux disease, Alcoholism, preoperative sepsis, preoperative shock.

Nonmodifiable procedure-related risk factors

Mechanical ventilation strategy, general anesthesia, long acting neuro–muscular blocking drugs, open abdominal surgery, perioperative nasogastric tube, intraoperative blood transfusion.

Modifiable procedure-related risk factors

Type of surgery, duration of surgery, Emergency surgery, re-operation.

Laboratory testing

Urea >7.5 mmol./lit, increased creatinine, abnormal liver function tests, low preoperative oxygen saturation, positive cough test, abnormal preoperative Chest X ray, preoperative anemia, low albumin levels, FEV1/FVC <0.7 and FEV1 <80% of the predicted.

Canet et al.^[30] hypothesizing that PPC occurrence could be predicted from a reduced set of perioperative variables, aimed to develop a predictive index for a broad surgical population. They conducted a prospective, multicenter study of nearly 2500 patients in Catalonia, Spain, in which, seven factors (age, preoperative SpO₂, acute respiratory infection during the month before surgery, preoperative anemia, type of incision, duration of surgery, and emergency surgery) provided a sensitive and specific prediction of risk for PPCs. They developed ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia) score:[Table 1]

Table 1: Variables in assess respiratory risk in surgical patients in Catalonia score

Click here to view

Three levels of risk were indicated by the following cutoffs

<26 points-low risk
26–45 points-moderate risk and
>45 points-high risk.

Incidence of PPCs in ARISCAT study was 5%.

The highest PPC rate was among intrathoracic (37.8%) followed by upper abdominal (12.2%) and peripheral surgeries (2.2%).

Mazo et al.^[27] conducted a study in Europe to externally validate ARISCAT score (PERISCOPE cohort [Prospective evaluation of a risk score for PPCs in Europe]). Incidence of postoperative pulmonary complications in PERISCOPE study was 7.9%. For cutoff >26, sensitivity and Specificity of ARISCAT score were found to be 69.31% and 75.25%, respectively. For cutoff >45, sensitivity and specificity of ARISCAT score were found to be 34.90% and 95.10%, respectively.

In 2015, Canet et al.^[13] have done secondary analysis of the PERISCOPE cohort data, with a sample size of 5384 patients and developed and validated a score to predict postoperative respiratory failure (PRF). The incidence of PRF was 4.2%, and seven factors were used to stratify patients into low-, intermediate-, and high-risk groups, with incidences of PRF of 1.1%, 4.6%, and 18.8%, respectively. However, the independent variables differ slightly from those found in ARISCAT: low preoperative SpO₂, at least one preoperative respiratory symptom, chronic liver disease, congestive heart failure, intrathoracic/upper abdominal surgery, procedure >2 h, and emergency surgery.

Perilli et al.^[31] have done a study to evaluate the role of surgical setting (urgent versus elective) and approach (open versus laparoscopic) in affecting PPCs prevalence in patients undergoing abdominal surgery by using ARISCAT score. PPCs incidence was greater in urgent (33%) versus elective setting (7%) (P value-0.0001) and in open (6%) versus laparoscopic approach (1.9%) (P value-0.0006). PPCs occurrence was positively correlated with in-hospital mortality (P value-0.0001). Logistic regression showed that urgent setting (P = 0.000), ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia) score (P = 0.004), and age (P = 0.01) were predictors of PPCs. A cutoff of 23 for ARISCAT score was identified as determining factor for PPCs occurrence with 94% sensitivity and 29% specificity.

Aim and objectives

Aim of the study

To find the utility of ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia) score in predicting PPCs in patients undergoing Elective/Emergency surgery in a tertiary care hospital in India.

Objectives

To calculate the sensitivity, specificity of ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia) score in predicting PPCs in patients undergoing Elective/Emergency surgery in a tertiary care hospital in India.

To find the incidence of PPCs in various surgeries.

Materials and Methods

Study site

Apollo Main Hospital, Greams Road, Chennai.

Study population

Patients undergoing non-Obstetric Elective/Emergency surgery under General/Neuraxial/Plexus block anesthesia were recruited through simple random sampling technique.

Study design: Prospective Observational Study
Study period: September 2018 to March 2019.
Sample size: Three hundred and thirty cases (330).

Sample size with justification

Since the primary objective of the study is to find out the Sensitivity and Specificity of ARISCAT scoring system, we have taken sensitivity of 69% from PERISCOPE cohort study for the work-up of sample size calculation.

Using the following formula n = Z² pq/d²

Z = Standard normal variate value = 1.96

p = Sensitivity of ARISCAT score = 69%

q= (1-p) = 31%

d = Clinical allowable error (margin of error) = 5%

By substituting values in the formula, required sample size is 330 cases.

Inclusion criteria

Patients undergoing non-Obstetric Elective or Emergency surgical procedure under general, neuraxial or plexus block anesthesia were recruited through simple random sampling technique.

Exclusion criteria

1. Patients not giving consent for the study. 2. Age <16 years. 3. Obstetric procedures/any interventions during pregnancy. 4. Local/peripheral nerve anesthesia. 5. Procedures related to a previous postoperative complication. 6. Organ Transplantation. 7. Preoperatively intubated patients. 8. Out-patient procedures 8. Out-patient procedures (<24 h hospital stay) 9. Laparoscopic surgeries.

Methodology

Patients undergoing non-Obstetric Elective or Emergency surgical procedure under general, neuraxial, or plexus block anesthesia were recruited through simple random sampling technique. After taking informed written consent, demographic details and clinical history were collected. Risk for postoperative pulmonary complications was assessed based on ARISCAT score. These patients were followed in the postoperative period till discharge to look for the following PPCs:

Respiratory failure
Pulmonary infection
Pleural effusion
Atelectasis
Pneumothorax
Bronchospasm
Aspiration pneumonitis.

The study participants were followed up daily from the day of surgery till their discharge from the hospital. Any event, such as hypoxia, cough, fever, breathlessness, wheezing, aspiration were recorded, and the necessary investigations such as ABG, Pulsoxymetry, Chest Xray were done to detect PPCs such as Respiratory failure, Pulmonary infection, Pleural effusion, Atelectasis, Pneumothorax, Bronchospasm, Aspiration pneumonitis.

Statistical methods

All continuous variables will be tested for normality by Shapiro–Wilks test. If they are normally distributed, they will be expressed as mean ± standard deviation. Non normally distributed continuous variables will be expressed by median (interquartile range). Qualitative variables will be expressed as percentages. Comparison of continuous variables, if any will be done by independent sample t-test.

ROC curve will be drawn to find the cut-off value, Sensitivity and Specificity of ARISCAT score in our cohort. Comparison of categorical variables will be done by either Chi-square test/Fisher's exact test. Data entry will be done in MS Excel spreadsheet. Data analysis will be carried out by version 25.0. All P < 0.05 will be considered significant.

Results

In this study, there were a total of 330 participants with 193 (58.5%) male and 137 (41.5%) female. Among the males, 22 (11.4%) developed PPC and in women, 9 (6.6%) developed PPC [Graph 1].

In the study population, 147 participants were under the age of 50 years, out of which 9 developed PPCs. 179 participants were between 51 and 80 years, out of which 22 developed PPCs. 4 participants were above the age of 80 years and none of them developed PPCs [Graph 2].

Among the total 330 participants, 304 (92.1%) were nonsmokers, out of them 26 (8.6%) developed PPCs. 26 participants (7.9%) were smokers, out of which 5 (19.2%) developed PPCs [Graph 3].

Among the total 330 participants, 105 (31.8%) had diabetes mellitus. Out of those who had diabetes mellitus, 17 (16.2%) developed PPCs. 225 (68.2%) participants were non diabetic, out of which 14 (6.2%) developed PPCs [Graph 4].

In this study, 34 (10.3%) patients had CAD, out of which 8 (23.5%) developed PPC. 296 (89.7%) patients did not have history of CAD, out of them 23 (7.8%) developed PPC [Graph 5].

Among the 330 patients, 124 (37.6%) patients have undergone orthopedic surgeries, 65 (19.5%) have undergone general and digestive surgeries, 45 (13.6%) have undergone urological surgeries, 26 (7.9%) have undergone cardiothoracic surgeries, 23 (7%) have undergone ENT (Ear, Nose, throat) surgeries, 18 (5.5%) have undergone plastic surgeries, 17 (5.2%) have undergone breast surgeries, 7 (2.1%) have undergone neurosurgeries, 5 (1.2%) have undergone vascular surgeries [Table 2].

Table 2: Distribution of population-based on surgical specialty

Click here to view

The incidence of PPCs among cardiothoracic surgeries was 57.7%, general and digestive surgeries was 20%, urological surgeries were 2.2%, orthopedic surgeries were 1.6%.

The patients who have undergone ENT, neurosurgeries, plastic surgeries, breast, vascular surgeries did not develop any PPC [Graph 6].

In this study, 31 patients developed PPCs [Graph 7].

Among the study population, 3.0% developed respiratory failure, 2.4% developed atelectasis, 2.1% developed pleural effusion, 0.6% developed bronchospasm, 0.6% developed respiratory failure and pleural effusion, 0.3% developed respiratory failure and pulmonary infection, 0.3% developed respiratory failure, pulmonary infection and pleural effusion [Graph 8].

Among the study population, 301 (91.2%) patients have undergone surgery under General anesthesia, out of them 29 (9.6%) developed PPC. 21 (6.4%) have undergone surgery under Neuraxial anesthesia, out of them 1 (4.8%) has developed PPC. 8 (2.4%) have undergone surgery under plexus block, out of them 1 (12.5%) has developed PPC [Graph 9].

Among the study population, 239 (72.4%) patients have undergone peripheral surgeries, out of which 7 (2.9%) have developed PPC. 64 (19.4%) have undergone upper abdominal surgeries, out of which 9 (14.1%) have developed PPC. 27 (8.2%) have undergone intrathoracic surgeries, out of which 15 (55.6%) have developed PPC [Graph 10].

In this study, 147 (44.5%) patients have undergone surgeries <2 h, out of which 3 (2%) developed PPC. 139 (42.1%) have undergone surgeries 2–3 h, out of which 10 (7.2%) developed PPC. 44 (13.3%) have undergone surgeries >3 h duration, out of which 18 (40.9%) developed PPC [Graph 11].

When univariate analysis was done for the study population, the variables like Diabetes mellitus, CAD, type of incision and duration of surgery were found out to be statistically significant.

Incidence of postoperative pulmonary complications based on ARISCAT score

When ARISCAT score was calculated for all patients, 244 (73.9%) patients had low-risk score (<26 points), 51 (15.5%) patients had moderate risk score (26–44 points), and 35 (10.5%) patients had high risk score (>45 points). The incidence of PPC was more among high-risk score group (45.7%) compared to moderate risk (17.6%) and low-risk groups (2.5%) [Table 3].

Table 3: The distribution of study population based on assess respiratory risk in surgical patients in Catalonia risk score

Click here to view

Association between postoperative pulmonary complications and median postoperative length of stay

The median postoperative LOS was longer in patients with PPC (11 days) than in those without PPC (5.6 days) [Graph 12].

Predictive accuracy of ARISCAT score

In this study, we calculated Youden index to determine the optimum cutoff point with good sensitivity and specificity to predict PPC. For a cutoff of 24.5 points, the Sensitivity, Specificity, PPV (Positive predictive value), and NPV (Negative predictive value) of ARISCAT score were 83.9%, 80.3%, 30.6%, and 98%, respectively [Table 4].

Table 4: Predictive accuracy of assess respiratory risk in surgical patients in Catalonia score

Click here to view

Area under the ROC curve drawn for ARISCAT score in the study population was 0.86 (95% confidence interval, 0.79–0.93) [Graph 13].

Discussion

PPCs are a major cause of postoperative morbidity, mortality, and longer duration of hospital stay. Attempts have been made to develop predictive models for postoperative pulmonary complications. Risk prediction models developed by Jeong et al.,^[7] Gupta et al.,^[8] Hua et al.,^[10] Blum et al.^[11] for predicting PPC were retrospective studies; but ARISCAT score was developed from a prospective study.

Risk prediction models developed by some studies included only specific group of surgeries. For example, Arozullah et al.^[4] study included noncardiac surgeries, Scholes et al.^[32] study included only upper abdominal surgeries and Yang et al.^[33] included only major abdominal surgeries. But ARISCAT score included and can be used in peripheral, upper abdominal, and intrathoracic surgeries.

Risk prediction models developed by some studies focused on single adverse outcomes. For example, Arozullah et al.^[4] and Gupta et al.^[8] study focused on postoperative respiratory failure, Gupta et al.^[9] study focused on postoperative pneumonia, Hua et al.^[10] study focused on unplanned intubation, Blum et al.^[11] study focused on acute lung injury/ARDS. ARISCAT score focuses on seven PPCs (Respiratory failure, Pulmonary infection, Pleural effusion, Atelectasis, Pneumothorax, Bronchospasm, and Aspiration pneumonitis).

For our total study population (n = 330), risk for postoperative pulmonary complications was assessed based on ARISCAT score and these patients were followed in the postoperative period till discharge to look for the PPC (postoperative pulmonary complications).

The incidence of PPC in our study was 9.4%. This was similar to the studies done by Jeong et al.,^[7] Mazo et al.,^[27] Canet et al.,^[30] which reported the incidence of PPC as 7.9%, 5%, and 6.8%, respectively. Respiratory failure was the most common PPC in our study (3.0%). This finding was similar to the studies conducted by Jeong et al.^[7] (3.4%), Canet et al.^[30] (2.6%), McAlister et al.^[34] (1.2%). Among the study population, 239 (72.4%) patients have undergone peripheral surgeries, 64 (19.4%) have undergone upper abdominal surgeries, and 27 (8.2%) have undergone intrathoracic surgeries. The incidence of PPC was more among the patients who have undergone intrathoracic surgeries (55.6%), compared to upper abdominal (14.1%) and peripheral surgeries (2.9%). This was statistically significant with P = 0.0001. Canet et al.^[30] in their study also showed that the incidence of PPC was more among the patients who have undergone intrathoracic surgeries (37.8%), compared to upper abdominal (12.2%) and peripheral surgeries (2.2%).

In this study, the incidence of PPC was more among surgeries more than 3 h duration (40.9%) compared to surgeries of 2–3 h (7.2%) and surgeries of <2 h duration (2.0%)). This was statistically significant with P value– 0.0001. The Odds ratio was 8.6 for surgeries more than 2 h duration. That means the surgeries with duration more than 2 h duration had 8.6 times more chance of developing PPC than surgeries <2 h duration. Canet et al.^[30] in their study found that Odds ratio for surgery more than 2 h duration was 4.9. McAlister et al.^[34] in their study also found that odds ratio for surgery more than 2 h duration was 3.3.

In our study, the incidence of PPC was more among emergency surgeries (15.4%) compared to elective surgeries (9.1%). This was similar to the study conducted done by Canet et al.^[30] which showed that the incidence of PPC was more in emergency surgeries (8.6%) compared to elective surgeries (4.4%). Perilli et al.^[31] in their study also showed that PPC incidence was greater in urgent (33%) versus elective setting (7%).

In our study, we found that the median postoperative length of stay in the hospital was longer in patients with PPC (11 days) than in those without PPC (5.6 days). Canet et al.^[30] in their study also observed that the median postoperative length of stay in the hospital was longer in patients with PPC (11 days) than in those without PPC (3 days). This shows that PPCs are a major cause of longer hospital stays in postoperative patients.

When ARISCAT score was calculated for all patients in our study, 244 (73.9%) patients had low-risk score (45 points). The incidence of PPC was more among high-risk score group (45.7%) compared to moderate risk (17.6%) and low-risk groups (2.5%), which was statistically significant with P value– 0.0001. This was similar to the study done by Mazo et al.^[27] which showed that the incidence of PPC was more among high-risk score group (38.01%) compared to moderate risk (12.98%) and low-risk groups (3.39%).

In this study, we derived a cutoff of 24.5 points by using Youden index and the Sensitivity, Specificity, PPV, and NPV of ARISCAT score for a cutoff of 24.5 points were 83.9%, 80.3%, 30.6%, and 98%, respectively. These findings were almost similar to the study done by Mazo et al.^[27] which showed that, for a cutoff of 26 points, the Sensitivity, Specificity, PPV, and NPV of ARISCAT score were 69.31%, 75.25%, 19.4%, and 96.6%, respectively. In the study done by V. Perilli et al.,^[31] a cut-off of 23 points for ARISCAT score was identified as a determinant for the occurrence of PPCs, with 94% sensitivity and 29% specificity.

Limitations

ARISCAT score predicts the risk of developing PPCs in patients undergoing surgery, but it cannot predict the severity of the pulmonary complications
This study was to look only at PPCs in patients till the time of their discharge from the hospital. Hence some PPCs might not have been detected in patients discharged early
As the study refers to a single-center regional database, our results require corroboration across diverse institutions and countries.

Conclusion

The incidence of PPCs in this study was 9.4%, which shows that they are one of the most common postoperative complications. The development of a risk score will help to estimate the patient's ability to tolerate a surgery; to take into consideration the choice of nonsurgical alternatives, or to postpone the surgery in high-risk patients; to explain the risk in patients undergoing surgery; and to take the measures needed to reduce the pulmonary complications after the surgery.

In our study, the incidence of PPCs in peripheral surgeries, upper abdominal and intrathoracic surgeries was 2.9%, 14.1%, and 55.6%, respectively. Furthermore, the incidence of PPC was more among surgeries more than 3 h duration compared to surgeries of 2–3 h and surgeries of <2 h duration, which shows the importance of optimizing the preoperative condition of patients undergoing upper abdominal, intrathoracic surgeries and surgeries of longer duration (>3 h).

In our study, the Sensitivity, Specificity, PPV, and NPV of ARISCAT score were 83.9%, 80.3%, 30.6%, and 98%, respectively. Hence, its enormous utility, in that; it can be used as a routine screening tool for predicting the risk of developing PPCs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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