A model incorporating factors such as lymphocytes and lung lesions differentiated adenovirus pneumonias from Chlamydia psittaci (CPP) in a multicenter study of nearly 200 individuals.
Symptoms of pneumonia caused by CPP are often confused with other respiratory infections, particularly adenovirus pneumonia (AVP), which can delay correct diagnosis and impact treatment, Yi Li, MD, of Xiangya Hospital, Central South University, Changsha, China, and colleagues wrote. Detailed comparisons of the two conditions are lacking.
In a retrospective study published in the International Journal of Infectious Diseases, the researchers examined laboratory, clinical, and radiological differences and created a nomogram to distinguish CPP from AVP. The study population included 78 adults with CPP and 102 with AVP who were seen at a single center in China. The mean ages of the CPP and AVP patients were 61.0 years and 38.5 years, and 57.7% men and 91.2% men, respectively. Patients with CPP were significantly more likely to have hypertension and diabetes at baseline, compared with the AVP group.
The primary outcome was 30-day mortality after hospital admission, which was 10.3% and 14.7% for the CPP and AVP patients, respectively (P = 0.376). However, the incidence of cardiac injury was significantly higher in AVP patients versus those with CPP (48.0% vs. 11.5%; P < 0.001).
In a multivariate analysis, age, sex, nervous system symptoms, lymphocyte count, C-reactive protein level (CRP), and bilateral lung lesions were risk factors for CPP. The researchers combined these factors into a nomogram that showed a concordance value of 0.949 for differentiating between the CPP and AVP groups.
Overall, CPP patients were older, had more nervous system symptoms, and had higher CRP levels, compared with patients with AVP, who were more likely to be men and to have higher lymphocyte percentages and more bilateral lung lesions on chest imaging.
The current study is the first known to provide a way to distinguish CPP and AVP, the researchers wrote. “The antibiotic treatments, prognoses, and life support measures of CPP and AVP are considerably different. Therefore, differentiating the two diseases through early identification of specific clinical characteristics is vital.”
The findings were limited by several factors including the small sample size, retrospective design, and the use of mNGS to diagnose CPP in the absence of standard clinical diagnostic kits, which may have resulted in underestimated CPP incidence, the researchers noted.
However, “the nomogram we established combines patient data on age, sex, and readily available laboratory results to reasonably predict CPP, thus making rapid and direct diagnosis possible,” they said.
The study was supported by the Key R&D Program of Hunan Province, Project Program of National Clinical Research Center for Geriatric Disorders, National Natural Science Foundation of China, Hunan Natural Science Youth Foundation, and the national key clinical specialist construction programs of China. The researchers had no financial conflicts to disclose.