Development and validation of a semi-automated surveillance system - Lowering the fruit for non-ventilator-associated hospital-acquired pneumonia (nvHAP) prevention.

OBJECTIVES: Conducting manual surveillance of non-ventilator-associated hospital-acquired pneumonia (nvHAP) using ECDC (European Centre for Disease Prevention and Control) surveillance criteria is very resource intensive. We developed and validated a semi-automated surveillance system for nvHAP, and describe nvHAP incidence and etiology at our hospital.

METHODS: We applied an automated classification algorithm mirroring ECDC definition criteria to distinguish patients 'not at risk' from patients 'at risk' for suffering from nvHAP. 'At risk'-patients were manually screened for nvHAP. For validation, we applied the reference standard of full manual evaluation to three validation samples comprising 2091 patients.

RESULTS: Among the 39,519 University Hospital Zurich inpatient discharges in 2017, the algorithm identified 2454 'at risk'-patients, reducing the number of medical records to be manually screened by 93.8%. From this subset, nvHAP was identified in 251 patients (0.64%, 95% Confidence interval (CI): 0.57-0.73). Sensitivity, negative predictive value, and accuracy of semi-automated surveillance vs. full manual surveillance were lowest in the validation sample consisting of patients with HAP according to International Classification of Diseases (ICD-10) discharge diagnostic codes, with 97.5% (CI: 93.7 - 99.3%), 99.2% (CI: 97.9 - 99.8%), and 99.4% (CI: 98.4 - 99.8%), respectively. The overall incidence rate of nvHAP was 0.83/1000 patient days (95% CI: 0.73 - 0.94), with highest rates in hematology/oncology, cardiac and thoracic surgery, and internal medicine including subspecialties.

CONCLUSIONS: The semi-automated surveillance demonstrated a very high sensitivity, negative predictive value, and accuracy. This approach significantly reduces manual surveillance workload, and thus making continuous nvHAP surveillance feasible as a pivotal element for successful prevention efforts.