Introduction

Hospital-acquired infections (HAIs) are common: at any one time about 1 in 10 patients in acute care hospitals have an HAI, and an additional 10-60% of infections may present after discharge.

HAI is an important cause of morbidity and mortality and therefore should be rigorously controlled as part of the general duty of patient care. But HAI also has considerable ‘economic' impact on hospital services and on the costs of national health care.

The economic consequences of hospital-acquired infection

Measurement of the costs of HAI is difficult and the financial impact varies between different healthcare systems. Nevertheless, in simple terms, HAI can have the following economic results:

(1) HAI delays patient discharge, resulting in increased ‘hotel' costs. In addition, the patient suffers additional costs due to increased absence from work and relatives suffer costs of time and travel to visit the patient;

(2) Infections require increased treatment costs (for example, increased drug therapy and increased numbers of procedures, including repeat surgery). The patient may be discharged from hospital while infected and the increased treatment costs then fall on General Practice or community services;

(3) HAI is accompanied by increasing numbers of laboratory and imaging investigations;

(4) HAI increases infection control costs, including epidemiological investigations and medical, nursing and management time; and

(5) HAI is often the subject of litigation, the costs of which may be huge.

Increased rates of HAI associated with blocked beds and closed wards and theatres, results in increased unit costs for admissions and procedures, lengthening waiting lists and failure to complete contracts. All these have financial penalties. Patient morbidity resulting from HAI will also have large community and society costs that are difficult to quantitate but may have considerable impact. Also difficult to measure in economic terms is loss of reputation – either for the whole hospital or for individual units – which has significant impact on contracts and patient referral.

Overall cost estimates

Although the measurement of costs of HAI is difficult, a number of studies have shown the probable magnitude of the problem. A 1999 study was done by Plowman and colleagues in the UK . They studied 4000 adult patients in an English district general (community) hospital during 1994 – 1995 [1]. Costs will be different for other countries and will change with time, however the relative magnitudes will be similar. A smaller study by Coello et al in 1993 in England showed similar costs [2].

In the Plowman study, 7.8% of patients had HAI identified in hospital. In addition, 19% of patients who were not diagnosed with HAI in hospital, and 30% of those who were, reported symptoms of HAI after discharge. Patients with HAI diagnosed in hospital remained in hospital about 2.5x longer than uninfected patients, an average of 11 additional days. (Figure 13.1) They had increased hospital costs about 2.8x greater than uninfected patients, averaging about £3,000 ($5,000) per case (Figure 13.2). 13% of infected patients died compared with 2% of those uninfected. Adjusted for age, sex, co-morbidity and other factors, the death rate was 7 times higher for patients with HAI. Table13.1 shows the additional length of hospital stay associated with HAI in other studies).

Estimated costs of HAI to the hospital in the Plowman study was £3.6m ($5.8m). Costs might be expected to be higher in tertiary referral hospitals.

The extrapolated national annual cost burden of HAI for hospitals was about £1b ($1.6b), equivalent to about 1% of the total national hospital budget or the resources of twenty-seven 400-bedded general hospitals. The national annual post discharge costs were estimated to be about £56m ($90m). This included General Practice costs of £8.4m, hospital out-patients £27m, and community nursing services £21m.

It was estimated that HAI was the direct cause of about 5000 deaths per annum in England (more than those caused by suicides or traffic accidents) and contributed to an additional 15,000.

In the USA, HAI is amongst the top ten causes of death [3,4]. The US Institute of Medicine estimates that preventable adverse patient events, including hospital-acquired infections, are responsible for 44,000-98,000 deaths annually in the US at a cost of $17-$29 billion [5]. The US National Nosocomial Infection Surveillance system had a positive impact on reducing HAI rates in participating hospitals [6].

In Mexico, Navarrete-Navarro and Armengol-Sanchez [7] estimated costs associated with HAI in pediatric intensive care. Infected children had an excess hospital stay of 9.6 days. This was the major factor contributing to an average cost per infection of nearly $12,000.

Costs of outbreaks

Several studies have attempted to measure the costs associated with hospital outbreaks of infection. Again, the costs are tentative and must be considered in relation to the health care system studied and the year of study. Nevertheless, again the costs have been shown to be considerable.

Cox et al. [8], estimated the additional costs generated by a large outbreak of methicillin-resistant S. aureus (MRSA) over three years in an English district general hospital as £400,000 ($640,000). A smaller MRSA outbreak cost £7000, however an outbreak of multidrug resistant Gram-negative infection increased costs by about £35,000 ($56,000) (1990 prices) [9]. Kim et al [10] measured the costs of MRSA in their hospital and calculated that MRSA cost all Canadian hospitals $42m - $59m annually in 1997 dollars.

Cost benefit of infection control

In the Study on the Efficiency of Nosocomial Infection Control (SENIC) of 1974-1983 [3], US hospitals with one full-time infection control nurse (ICN) per 250 beds, an infection control doctor (ICD), moderately intense surveillance, and system for reporting wound infection rates to surgeons, reduced their HAI rates by 32%. In the other hospitals, the HAI rate increased by 18%. The SENIC study estimated that (in 1975 dollars), the annual cost of HAI in US hospitals was $1b. The cost of infection control teams (0.2 ICD, 1 ICN, 1 clerk per 250 beds) was $72m per annum, only 7% of the infection costs. Therefore, if infection control programmes were effective in preventing only 7% of nosocomial infections (normally distributed), the costs of the programmes would be covered. A 20% effectiveness would save $200m, and 50% would save $0.5b (1975 US prices).

Conclusions

The costs of HAI are huge and include patient morbidity and mortality, hospital and community medical costs, the impact of blocked beds, and wider socio-economic costs. The costs of infection control programmes and staffing are relatively small and with only a small degree of effectiveness they can pay for themselves. Investment in infection control is therefore highly cost effective.

References

1. Plowman R, Graves N, Griffin M, Roberts JA, Swan AV, Cookson BD, Taylor L. Socio-economic burden of hospital acquired infection. London : PHLS, 1999. Back to text

2. Coello R, Glenister H, Fereres J, Bartlett C, Leigh D, Sedgwick J, Cooke EM. The cost of infection in surgical patients: a case-control study.  Journal of Hospital Infection 1993;25:239-50. Back to text

3. Haley RW, Culver DH, White JW, Morgan WM, Emori TG, Munn VP. Hooton TM. The efficacy of infection surveillance and control programs in preventing nosocomial infections in US hospitals. American Journal of Epidemiology 1985; 121:182-205. Back to text

4. Wenzel RP, Edmond MB . The Impact of Hospital-Acquired Bloodstream Infections. Emerging Infectious Diseases 2001; 7:174-177 . Back to text

5. Kohn L, Corrigan J, Donaldson M. To err is human: building a safer health system . Washington , DC : Institute of Medicine , National Academy Press, 1999. Back to text

6. Report. Monitoring Hospital-Acquired Infections to Promote Patient Safety -- United States, 1990-1999. MMWR 2000; 49:149-153. Back to text

7. Navarrete-Navarro S, Armengol-Sanchez G. Secondary costs due to nosocomial infections in 2 pediatric intensive care units. [Spanish] Salud Publica de Mexico 1999; 41 Suppl 1:S51-8. Back to text

8. Cox RA, Conquest C, Mallaghan C, Marples RR. A major outbreak of methicillin-resistant Staphylococcus aureus caused by a new phage-type (EMRSA-16). Journal of Hospital Infection 1995; 29:87-106. Back to text

9. Mehtar S. How to cost and fund an infection control programme. Journal of Hospital Infection 1993; 25:57-69. Back to text

10. Kim T, Oh PI, Simor AE. The economic impact of methicillin-resistant Staphylococcus aureus in Canadian hospitals. Infection Control & Hospital Epidemiology 2001;22:99-104. Back to text

11. Wilcox MH, Dave J. The cost of hospital-acquired infection and the value of infection control. Journal of Hospital Infection 2000;45:81-4. Back to text