Problematic linkage of publicly disclosed hand hygiene compliance and health care-associated Staphylococcus aureus bacteraemia rates

To the Editor: We read with interest the letter by Playford and colleagues, but important questions remain about the authors’ methods and conclusions.1 First, not only do the data periods for assessing hand hygiene (HH) compliance and for rates of health care-associated Staphylococcus aureus bacteraemia (HCA-SAB) not overlap, but the data period for HCA-SAB rates precedes the HH compliance data period. Second, the study design is potentially flawed since there are no published data to suggest that a single cross-sectional HH compliance rate (as reported by the authors) correlates with observed rates of HCA-SAB. Instead, previous studies have described stepwise improvements in HH compliance over periods of 12–24 months, with temporal changes in SAB rates (specifically methicillin-resistant S. aureus [MRSA]) using statistical methods that assess trends over time rather than a single annual rate, such as that reported on the MyHospitals website.2-5 Thus, the authors’ analysis is not based on any previously validated approach. We agree that HCA-SAB rates are not related to HH compliance alone, but this has never been suggested by the National Hand Hygiene Initiative (www.hha.org.au). Issues such as invasive device insertion and maintenance, host factors and rates of staphylococcal infection in the community are all likely to have an impact.4 Studies that quantify the impact of such factors are difficult to undertake accurately, although Victorian data suggest that HH programs alone have the potential to reduce rates of MRSA bacteraemia by approximately 66%, albeit from a rather high pre-intervention rate.3 Hospital-acquired infections are a complex multifaceted issue that requires careful analysis and investigation.