Discussion

We found that HAIs used 155,978 bed days in public hospitals annually, with a cost of SGD151 million (US$114 million) annually if accounting methods are used to value resources. Our scenario analyses revealed that the cost savings from the proportion of preventable HAIs is substantial. Our results are useful in informing future economic analyses of hospital-based infection control programs.

Monetary valuations of HAIs vary by healthcare setting and funding structures. In Singapore, >80% of the acute inpatient care is provided by 10 public hospitals in 3 healthcare clusters. Within these hospitals, the majority of the annual budget is provided by the government through block-based and activity-based funding, which allocates a fixed amount for each average admission. Because we can assume that the fixed amount will consider potential adverse events during admission, the additional bed days used by patients with HAIs may not incur a direct cost to the hospital. However, important opportunity costs can be avoided by controlling HAIs, in addition to reputational gains. Each bed day can be used in other health-producing activities and can potentially result in monetary gains. This factor is particularly relevant in our local context, given that bed occupancy rates in most Singapore public hospitals often exceed 85%–90%. ⁸

In contrast to previous studies directed at specific patient groups or organisms, we considered the cost of HAIs across all infection types, which allowed for comparison across different infections. SSIs were the greatest contributor to HAI costs, which highlights the importance of SSIs as a key target for future interventions. To estimate the cost of a hospital bed day in our study, we used historical accounting conventions. We acknowledge that our costs may not represent the opportunity costs that can be recovered if the bed days released, because our costs were produced with the aim of recovering hospital expenditure. ^{Reference Graves, Harbarth, Beyersmann, Barnett, Halton and Cooper9} In future studies, we will consider alternate methods to accurately conceive the opportunity costs of HAI, such as tabulating the cost of each bed day in their alternate uses, or conducting contingent valuation to assess decision makers’ willingness to pay for bed days. ^{Reference Page, Barnett and Graves10}

Our study has several limitations. First, we do not consider bed days lost in the private sector, productivity losses due to absenteeism, caregiver time, or morbidity sequelae and death. ^{Reference Graves, Harbarth, Beyersmann, Barnett, Halton and Cooper9} Hence, our findings may be less useful to private hospital administrators or to national policy makers. Second, infection control policy changes have been implemented due to the coronavirus disease 2019 (COVID-19) pandemic. This pandemic may have led to a reduction or a paradoxical increase in HAI incidences, and prevalence data from newer HAI surveys may more accurately reflect the current burden of HAIs in Singapore.

In summary, we described the annual bed days lost and economic burden of HAIs to Singapore hospitals. Future studies to elicit the opportunity cost of a bed day and to describe the economic impact of HAIs from patient and societal perspectives will be desirable.