Tjallie van der Kooi

Autopsy studies are the gold standard to assess construct validity of the contribution of HAI to death, but they are few and not recent (19‐22). Therefore, we applied three measures which had been proven valid before, in a single centre study(10), were based on related concepts(11) or were perceived useful by an expert panel. These measures were discussed and tested with case vignettes by the expert panel to further ensure face, content and construct validity. The correlation between the three measures supports the assumed validity. Another feature that can corroborate the content and construct validity of the measures is the perceived fit, which was reasonable or good in more than 88% for all measures. The OSI preferred WHOCAT and QUANT over 3CAT on the grounds that it better reflected the rationale (WHOCAT) or a more neutral and better fit of the mortality review (QUANT). The inter‐rater reliability varied with the type of HAI: it was the highest for pneumonia and the lowest for CDI. Differences in kappa were larger than differences in percentage agreement, which can partly be explained by the prevalence of the different categories. The reviewers agreed most often when the contribution of the HAI was assessed as definite or, slightly less, when assessed as possible, whereas agreement on ‘no contribution’ was lowest for BSI and CDI. The majority of CDI cases originated from three centres and 45% from one of these, which may have introduced bias. It was difficult to conclude whether the lower agreement observed in two of these centres was due to the type of infection, i.e. CDI, or resulted from factors specific for these centres. A BSI was usually considered to have contributed to the death of a patient, either ‘definitely’ or ‘possibly’, and a skewed distribution resulted in lower kappa values. There are a few reports on the inter‐rater reliability of HAI‐associated mortality review outcomes. In a study by Kaoutar et al (10), the review was performed by an infection prevention and control professional who also interviewed the TP. This procedure resembles the joint discussion after the independent review in our study and the agreement of 91% reported by Kaoutar et al is close to the 93% final consensus in our results. Michel et al reported a high inter‐rater reliability in a French hospital care‐related study on adverse events: 92% (kappa = 0.83; 95% CI: 0.67‐0.99) (23). The inter‐observer reliability (kappa = 0.4) reported by Langelaan et al in a Dutch study on adverse events was considerably lower (24). AMR was present in more than half of the BSI and pneumonia cases, which is higher than the approximately 30% expected in the overall population of patients (alive and deceased) with a HAI (estimated with the country‐specific AMR percentages from the 6 119 Mortality review reproducibility study

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