In this study, the incidence rate of HAIs was estimated at 17.1 per 1000 patient-days in the longitudinal study; however, this was 22.5 per 1000 patient-days for the routine surveillance system. However, the incidence rate of detection was higher in the routine surveillance, but the detection accuracy was low. In this regard, the sensitivity of the routine surveillance was 61.4%, the specificity was 82.6%, and the NPV was 89.7%. The main problem of routine surveillance was low PPV (46.5%). The lowest PPV was related to the detection of UTI (32.3%) and VAP (32.5%); however, the highest PPV was related to the detection of SSI (60.9%). The most significant challenges for detecting HAIs were lack of collaboration of ICLNs as well as lack of collaboration of laboratory supervisors.
In the longitudinal study, the incidence rate of HAIs was 17.1 per 1000 patient-days, and the most incident infection was related to SSI (6.5 per 1000 patient-days). The estimated incidence in this study was higher than estimates in Scotland (3.3 per 1000 patient-days) , Turkey (3.6 per 1000 patient-days) , China (3.6 per 1000 patient-days) ; however, it was lower than in Ethiopia (28.2 per 1000 patient-days) . The incidence of HAIs in a study conducted by Iranian nosocomial infection surveillance in 2020 (incidence rate 7.41 per 1000 patient-days) was lower than the estimated incidence in this study . The higher incidence rate of HAIs in this study compared to the estimated HAIs in the developed countries could be due to different reasons such as long length of hospital stay , various definitions, a low record of healthcare-associated infection in some regions, and a higher record of healthcare-associated infection in teaching hospitals . As healthcare-associated infections impose a significant burden on the system and patients , valid data is necessary to track, prevent, and control HAIs [20, 21]. Increasing the accuracy of surveillance systems and conducting multicenter longitudinal studies are necessary to estimate the incidence of HAIs better.
However, the routine surveillance in the hospital detected more cases than the longitudinal study, but the accuracy of reporting HAIs was low. The significant problem in the accuracy of HAIs detection was related to the low PPV. In this regard, the longitudinal study confirmed less than half of the detected cases as HAIs. PPV in all kinds of HAIs was low in the routine surveillance; however, the lowest PPV was reported on the diagnosis of UTI and VAP. Low PPV could be related to some items, including detection of HAIs based on the culture and the lack of access to clinical signs and symptoms , and the precision of some infection indices (e.g., the presence of fever in patients) was low . Empowering the routine surveillance system to diagnose and control HAIs at the national and hospital levels is necessary. The capacity of HAIs surveillance in diagnosis and control of HAIs is related to various factors, including hospital microbiology capacity, susceptibility testing, high staff turnover, the quality of patient medical records, and collaboration of ICLNs . In Iran, laboratory culture tests are an important part of detecting and controlling infections; however, intersectoral collaboration, standard laboratories, and supplies are limited . Surveillance requires information from emergency department reports, admission history, and physical reports, including signs, symptoms, bedside interventions, diagnostic imaging, physician impressions, general consulting reports, antimicrobial treatment, and physician impressions . The surveillance system may have missed this information, resulting in an error in detecting HAIs . A computerized surveillance system to detect respiratory infections and SSIs, as well as the use of technologies to gain access to patient signs, symptoms, interventions, and physician assessments, are required . As a result, we recommend improving intersectoral collaboration and laboratory capacity and developing the HIS.
Lack of collaboration from ICLNs, and laboratory supervisors were the main barriers of the detection and control of HAIs in Iran. A study in Iran reported that poor intersectoral partnership was one of the barriers of controlling HAIs . Microbiology reports and patient medical charts are required for case detection in HAIs surveillance . For instance, patient medical records and microbiologic evidence of pulmonary parenchymal infection are critical for VAP diagnosis, and impact VAP incidence and outcome reports . Moreover, if the primary case-finding method in SSI is only based on microbiology reports, the ICN may miss SSI or some cases detected as SSI, incorrectly . Although the laboratory surveillance method has a high sensitivity, approximately one out of every four cases of HAIs classified using the laboratory method are not true HAIs . Weaknesses in case finding , and the use of laboratory results alone , may cause misdiagnosis of HAIs . So, some multidisciplinary interventions and a decrease of barriers are necessary to report and control HAIs . Therefore, it is advisable that policymakers focus on detecting and removing the barriers of the surveillance system's accuracy. This could improve the surveillance system’s ability to detect HAIs.
This study had three limitations. First, we collected data from a tertiary-care teaching hospital in southeast Iran, thus, generalizability of the findings to other hospitals in the country may be difficult. Second, patients were not followed up after discharge, so we might have missed some cases after discharge which may underestimate the reported incidence rate. Third, although antibiotic use is prevalent in hospitalized patients, some patients may not show the signs of infection, which could underestimate the HAIs.