A study of the clinical and radiological resolution of community acquired Pneumonia

Abstract

Background: Community-Acquired Pneumonia (CAP) is one of the most common and morbid conditions encountered in clinical practice (1-3). Clinicians are frequently faced with patients in whom the radiographic resolution of community-acquired pneumonia seems delayed. Previous studies on the radiographic resolution of CAP have yielded conflicting results with reports like 43% (4), 68.4% (5) and 95% (6) of patients getting complete radiological resolution at 4 weeks follow up.
Aims And Objectives: To study the time taken for radiological resolution of pneumonia and to correlate it with the clinical resolution, and to understand the effect of various patient-related and infective agent factors that affect the time taken for radiological resolution in CAP.
Study Design: Prospective Cohort Study,2017-2019
Participants: Patients admitted in SKIMS with a diagnosis of Community-acquired Pneumonia.
Methods: The patients were subjected to clinical examination, complete blood counts, blood tests for liver and kidney function, blood gases with serum electrolytes and appropriate microbiological studies in the form of blood culture, sputum culture, urinary antigen for pneumococcus and Legionella, serology for Mycoplasma and Chlamydia and real-time reverse transcriptase polymerase chain reaction for influenza viruses. Chest radiographs were taken at the time of admission. The patients were treated with standard antimicrobial therapy and were followed at two, four, eight and twelve weeks for assessment of the clinical improvement (resolution of fever, cough, expectoration and WBC counts return to normal) and for radiological resolution of serial Chest radiographs.
Results: The study population consisted of 176 patients; age ranged from 20 to 90 years (median 60 years);109 (61.9%) patients were male and 67 (38.1%) were female. Hypertension (n= 116, 65.9%) and COPD (n=45, 25.6 %) were the most common associated comorbidities . In our study, eighty-nine (50.6 %) patients were current smokers; Pneumonia Severity Index (PSI) Class ≥4 comprised 44.3% of the population; Streptococcus pneumoniae (31 %) was the most common respiratory pathogen detected. The overall mortality at thirty- days was 30 (17.04%). On repeat chest radiographs at 2 weeks, 4 weeks, 8 weeks and 12 weeks follow up , complete radiological resolution was documented in n= 21 (30%), n=27 (38.5%, cumulative 68.5%), n=18 (25.7%, cumulative 94.2%) and n=4 (5.9%, cumulative 100%) patients respectively. On Univariate analysis, older age (p=0.023), current smoker (p=0.001), underlying COPD (p=0.023), low oxygen saturation (p=0.005), higher PSI Class (p= ≤0.001) where statistically significant factors associated with delayed radiologic resolution. On multivariate analysis, smoking was an independently significant factor associated with delayed radiological resolution (p=0.007).
Conclusion: In our study, we tried to determine the radiological resolution of CAP and any factors that influence the resolution. We found that the radiological resolution of CAP occurs in the majority (68.5%) of the patients at four weeks from the time of clinical presentation. Smoking is an independent risk factor associated with delayed radiological resolution in CAP.