Objective: 

Postoperative pneumonia (POP) is a frequent complication after cardiac surgery, which significantly worsens prognosis. This study aimed to identify preoperative and intraoperative factors independently associated with POP in a cardiac surgery cohort, perform a systematic review (SR) and meta-analysis of risk factors, outcomes, and predictive models, and validate these models in the cohort.

Design: 

This is an ancillary study of the STERNOCAT (Catheter Outcomes With Sternotomy Cardiac Operated) trial completed by an SR and meta-analysis. PubMed, Embase, and Cochrane Library were searched (January 2000 to March 31, 2025). Two reviewers independently screened references to identify studies on adult cardiac surgery patients assessing POP risk factors or predictive models, extracted data, and assessed methodological quality. Predictive models identified through the SR were externally validated using the STERNOCAT cohort.

Setting: 

Cardiac surgery units in France (STERNOCAT cohort) and international hospital settings (SR studies).

Patients: 

A total of 1,470 patients from the STERNOCAT cohort and 172,079 from 24 studies overall were included in the SR.

Interventions: 

None.

Measurements and Main Results: 

In the STERNOCAT ancillary study, 78 of 1470 patients developed POP (5.3%). Independent risk factors included ischemic cardiomyopathy (odds ratio [OR] 1.89, 95% CI [1.13–3.16]), cardiopulmonary bypass (CPB) duration (OR 1.10, 95% CI [1.02–1.18]), and catecholamine use (OR 4.07, 95% CI [2.45–6.76]). POP was associated with higher 30-day mortality (14.1% vs. 1.5%, p < 0.0001). The meta-analysis identified 14 significant risk factors for POP. Of these, 10 were non-modifiable (e.g., age, diabetes mellitus, chronic obstructive pulmonary disease, chronic renal disease, previous cardiac surgery, emergency surgery). Four were partially modifiable: active smoking, CPB duration, intraoperative transfusions (presence and amount). Only one model, limited to preoperative variables, could be externally validated and showed poor accuracy.

Conclusions: 

This study highlights the difficulty of predicting and preventing POP, as most identified risk factors are non-modifiable or require long-term preventive strategies. Perioperative optimization, particularly regarding CPB management and transfusion practices, therefore, remains essential to improving patient outcomes.