OBJECTIVES

: The true economic burden of influenza is likely to be underestimated as it is the complications of influenza and exacerbations of existing chronic conditions which result in the highest burden on the healthcare system. This study will investigate healthcare resource use for clinical at-risk groups hospitalised due to influenza, compared to a control group without influenza diagnosis.

METHODS

: We analysed five years of hospital episodes statistics (HES) data (April 2013-March 2018) to extract patients coded with an influenza diagnosis and a concurrent diagnosis of chronic heart disease (CHD), chronic respiratory disease (CRD), or diabetes; matched, non-influenza patients for each clinical risk group were also extracted as a control group. Total costs per patient and number of care events were evaluated between the groups. Statistical differences were obtained by performing a T-test (one tail, assuming unequal variance). Linear regression control and sample matching methodologies were used to minimise confounding issues.

RESULTS

: A total of 70,625 patients with influenza diagnosis were identified. Of these, 41.0% had CRD, 37.3% had CHD, and 16.5% had diabetes. After variable adjustment, total secondary care costs were significantly higher for patients infected with influenza in all three clinical risk groups when compared to a non-infected control group (£33,242 vs. £20,520 for CHD; p<0.0001, £28,078 vs. £18,005 for CRD; p<0.0001, and £31,375 vs. £20,142 for diabetes; p<0.0001). Influenza-diagnosed patients also had a significantly higher number of care events in all groups. Similar statistically significant results were obtained when assessing the cost impact by different age groups (18-49, 50-64, and ≥65s).

CONCLUSIONS

: This study provides contemporary real-world evidence on the secondary care system burden of influenza hospitalisation for patients in clinical risk groups. Understanding and reducing the disease burden in these groups should form an integral part of UK NHS winter planning processes.