Introduction National guidelines on management of pneumonia stipulate the need for radiological evidence of consolidation to confirm the diagnosis. An incorrect diagnosis may lead to sub-optimal management, inappropriate antibiotic use and prolonged hospital stay. We sought to determine the relationship between clinical diagnosis of pneumonia and radiological evidence on chest x-ray.
Methods We performed a retrospective case-note study of admissions with a diagnosis of pneumonia in a large district general hospital during a three month period. Cases with pneumonia were identified using the ICD-10 coding system; those with co-existing diagnoses of malignancy or bronchiectasis were excluded. Clinician diagnoses of pneumonia were established by examination of clinical discharge summaries. All chest radiographs performed throughout the admission episode had been evaluated by a radiologist. Serum white cell count (WCC) and C-reactive protein (CRP) at admission were also examined.
Results 132 coded records of pneumonia were identified, of which a clinician diagnosis of pneumonia was recorded on 91. Median (interquartile range) age was 75 (61–89) years, 57% female, and median length of stay was 9 (3–23) days. CAP accounted for 65%, hospital acquired pneumonia 15%, aspiration pneumonia 1% and in 19% the origin was unclear. In 37% of all cases, there was no evidence of consolidation on any of the chest radiographs performed during inpatient stay. Subjects without radiological consolidation had similar length of stay to those with consolidation. There was no significant difference in age (p=0.34) or gender (p=0.28) between groups. WCC and CRP were significantly lower in those without consolidation. Analysis of cases where pneumonia was highlighted as the primary reason for admission (n=47) was similar to the overall cohort: 26% had no radiological evidence of consolidation.
Conclusion A significant proportion of clinical diagnoses of pneumonia are made despite no radiological evidence of consolidation. Studies are required to investigate if this could be due to a lack of awareness of diagnostic criteria, mismatch in chest x-ray interpretation or other factors in the clinical presentation.