Correlation Between PSI Score and Clinical Outcome in Patients with Viral Pneumonia

INTRODUCTION

Viral pneumonia is a leading cause of global respiratory morbidity and mortality, especially among the elderly, immunocompromised, and with chronic comorbidities.1 Viral pneumonia accounts for a rising proportion of hospitalizations due to lower respiratory tract infections, especially in the context of large-scale outbreaks such as the 2009 H1N1 influenza pandemic and the current critical situation caused by the pandemic of coronavirus (bearing the name of its virus).2-3 This events increased attention in the importance of developing risk stratification tools to facilitate effective early clinical decision-making and optimise the outcome of patients with viral pneumonia.4-5

The Pneumonia Severity Index (PSI) or PORT score, was initially conceived to identify patients with low risk of disease progression in community-acquired pneumonia (CAP) who could be safely managed as an outpatient.6 PSI uses 20 different variables such as age, comorbid conditions, vital signs and laboratory findings to determine 5 different risk classes with progressively increasing 30-day mortality.7-8 While PSI has undergone extensive validation in bacterial cases of CAP, the prognostic significance of PSI in viruses (influenza and coronavirus in general) and seasonal influenza cases and in the case of a novel coronavirus.9-10

Several studies have suggested PSI to have predictive value for mortality and clinical deterioration in viral pneumonia and seems to do so more often than other scoring systems, such as CURB-65 and qSOFA, in patients with Covid-19, often to a better extent.11-12 However, questions remain about its use in persons who are younger and without comorbidities - who may score low despite abundant viral pathology - and in settings where rapid lab diagnostics are not readily available.13

In a study, in-hospital mortality was noted in 15.9% and the correlation between PSI and clinical outcome (in-hospital mortality) was 0.95.14 In another study, the mortality rate was 16% and the length of hospital stay was 10.6±6.4 day. Mortality showed a moderate inverse correlation with PSI score (r = –0.333, p = 0.044) indicating that higher scores are associated with earlier in-hospital mortality.15

Given the growing numbers of cases of viral pneumonia and the need to have scalable triage tools during viral outbreaks, the evaluation of the correlation between the PSI score and clinical outcome such as in-hospital mortality is timely and clinically relevant. A better understanding of this relationship could refine existing protocols to better predict early risk stratification and ultimately use more efficient resources and show improvements in patient outcomes.

METHODOLOGY:

The study was conducted in the Department of Pulmonology at Liaquat National Hospital, Karachi, over a period of three months (11/7/25 to 10/10/25) following the approval of the synopsis. It employed a cross-sectional study design with a non-probability consecutive sampling technique. A total of 90 patients were included in the study, with the sample size determined through statistical power analysis, considering a 5% significance level for Type I error and a 10% significance level for Type II error. The calculation also accounted for an anticipated correlation coefficient of 0.95 between the Pneumonia Severity Index (PSI) score and in-hospital mortality among patients with viral pneumonia.14

Patients aged between 16 and 70 years of both sexes, who presented with clinical features consistent with viral pneumonia, were included in the study. Viral pneumonia was defined based on the presence of pulmonary infiltrates on chest radiography or computed tomography within the first 48 hours of admission, accompanied by either productive or non-productive cough, a body temperature greater than 37.8 °C or below 36 °C, and at least one systemic inflammatory biomarker such as leukocytosis greater than 10,000/mm³, leukopenia below 4,000/mm³, elevated C-reactive protein, or raised procalcitonin levels. Patients were excluded if they had bacterial or fungal co-infections diagnosed at admission, were pregnant or breastfeeding, or had immunocompromised states due to hematological malignancies or ongoing chemotherapy. Cases with missing or incomplete clinical records, including data required for PSI calculation or outcome assessment, as well as those who died or were discharged within 24 hours of admission, were also excluded.

After ethical clearance of the institutional review board and the College of Physicians and Surgeons Pakistan (CPSP), the written informed consent of all the eligible participants was obtained. Demographic and clinical characteristics (including name, age, and gender, body mass index (BMI), history of diabetes and smoking status (>5 pack years), hypertension [defined as blood pressure >140/90 mmHg], and duration of pneumonia symptoms] were documented at a detailed level at the time of data collection. Laboratory investigation performed within the first 24 hours of admission included complete blood count, neutrophil-lymphocyte ratio (NLR), serum ferritin, D-dimers and lactate level.

The Pneumonia Severity Index (PSI) was determined for the individual patients with the standard scoring system, which includes several demographic, clinical, and laboratory variables such as age, comorbidities, physiologic variables, and other pertinent findings. Patients were then divided into five PSI risk classes (I-V) with Class I having the least risk and Class V having the greatest risk. Outcome data was obtained from the hospitalisation records, including length of hospitalisation and hospital death. And in case the patient died, the number of days between admission and death was recorded too. All data were entered in a standardised spreadsheet and independently checked by two researchers to ensure the accuracy and consistency of data entry.

Data analysis was carried out by using the version 26.0 of the software for statistical analysis (SPSS). Quantitative variables, such as age, BMI, duration of symptoms, and PSI score, were reported as mean +- standard deviation and qualitative variables, such as gender, diabetes, smoking, hypertension, and in-hospital mortality, were reported as frequencies and percentages. The relationship between the PSI score and the mortality in hospital was analysed using Karl Pearson's correlation coefficient (r). The data were also stratified according to age, gender, BMI, duration of symptoms, diabetes, smoking and hypertension and Pearson's correlation test was re-applied after stratification. P-value of <=0.05 was determined as statistically significant.

RESULTS

Table 1 shows the distribution and descriptive results for demographic characteristics and clinical characteristics divided between 90 patients diagnosed with viral pneumonia. Of the total studied population 54 (60%) were male and 36 (40%) were female and the mean age was 43.0 +- 16.37 years. The majority of patients (38.9%) were in the age group of 51-70 years followed by 32.2% were aged (31-50 years) and 28.9% were in (16-30 years) age group.

About body mass index (BMI), 49 (54.4%) patients were normal BMI, 34 (37.8%) patients were overweight and 7 (7.8%) patients were obese (mean (SD) BMI was 25.36 +- 3.29 kg/m2). The mean duration of symptoms before admission was found to be 6.49 asser plus and 3.51 asser; 56 patients (62.2%) presented within 7 days of the onset of symptoms and 34 (37.8%) had symptoms for longer than 7 days.

Among the comorbidities, 15 patients (16.7%) had diabetes mellitus. 19 (21.1%) were smokers and 14 (15.6%) had hypertension. The mean score of total PSI in the whole cohort was 74.0 (+30.47) indicating moderate to high severity level in most of the patients. In regards to clinical outcomes, two thirds (80%) of the patients survived and were discharged successfully, and one third (20%) died in the hospital.

Table 2 summarises the correlation of the Pneumonia Severity Index (PSI) score to the in-hospital mortality for patients with viral pneumonia. The Pearson correlation coefficient (r) was found to be -0.792 and the p-value was 0.0001. This result apparently shows a high and significant negative correlation between PSI score and in-hospital mortality. In practical terms this meant that as the PSI score rose, the likelihood of survival decreased and would therefore suggest that the higher the score in the PSI, the more risk associated with death during hospitalisation.

Stratified Analysis of Relationship Between Pneumonia Severity Index (PSI) Score and In-Hospital Death Stratified analysis was done to analyse the correlation of PSI score and in-hospital death for various demographic and clinical variables is presented in Table 3. A strongly negative correlation was found in all the subgroups, indicating that higher PSI scores were linked with increased in-hospital death, regardless of gender, age, BMI, and comorbid conditions. All correlation was statistically significant (p-value <= 0.001).

The stratified analysis confirmed that the PSI score did not lose its strong and significant predictive relationship with in-hospital mortality among all the populations, highlighting the clinical utility in patients with viral pneumonia or the estimate of this score as a reliable prognostic indicator.

Table-1: Frequency distribution of different variables (n=90)

Table-2: Correlation between PSI score and in-hospital mortality

Table-3: Stratification of correlation between PSI score and in-hospital mortality with respect to different variable