DISCUSSION

Our findings suggest that measuring product usage may be a useful tool for monitoring trends in hand hygiene compliance, particularly in non-ICU settings. In healthcare settings with many wards, measurement of product usage may be a time- and cost-efficient adjunct to already established methods for monitoring hand hygiene compliance. Our study adds to current knowledge by including a large number and variety of ward settings, including evaluating product usage metrics on both high- and low-performing units.

The weak correlation found between measures of product usage and direct observation in the ICU aligns with prior investigations.Reference Marra, Moura, Paes, dos Santos and Edmond ⁵ This finding suggests that, due to the inherently crude nature of the metric, product usage may not be useful for identifying small fluctuations in compliance, as may occur in high-performing units, but that in other clinical settings, product usage provides crude—but useful—information about compliance trends.

All studies of hand hygiene compliance monitoring methods are limited by the “gold standard” metric, typically direct observation.Reference Boyce ⁴ Recent studies called this “gold standard” designation into question,Reference Morgan, Pineles and Shardell ^{7 ,} Reference Filho, Marra and Magnus ⁸ as direct observation may be influenced by the well-described Hawthorne effect. Passive measures, including product usage, are not subject to these behavioral fluctuations in clinical practice.Reference Srigley, Furness, Baker and Gardam ^{2 ,} Reference Hagel, Reischke and Kesselmeier ⁹ Other limitations of direct observation include (1) that it may not work well in settings where there are fewer healthcare-worker–patient interactions and (2) that interactions may occur behind closed doors and curtains, limiting the ability of observers to collect high-quality data. Product usage metrics are not subject to these challenges and, thus, may provide useful information about what is occurring during these unobserved interactions. Electronic methods of monitoring hand hygiene compliance are also not subject to the Hawthorne effect or unobserved interactions, but they are considerably more expensive than product usage measures and may not be feasible in many healthcare settings.Reference Srigley, Lightfoot, Fernie, Gardam and Muller ^{3 ,} Reference McGuckin, Waterman and Govednik ⁶

Our study had several limitations. First, complete data were not available for all units for all quarters. However, because all units were sampled at least once yearly during the study period, this likely did not significantly impact our findings. Second, our study was completed in a single academic center, and results may vary in different clinical settings. Third, the units that were included in the study, including the ICUs, were diverse. Product usage metrics were adjusted for expected number of events on these units, however, likely did not fully account for the heterogeneity inherent in these interactions. This may have biased results against product usage metrics in some cases. Finally, direct observation was used as the “gold standard,” although this method is known to be imperfect.

In conclusion, the measurement of product utilization rates is a practical and inexpensive method for estimating hand hygiene compliance, particularly in non-ICU settings that are difficult to monitor using direct observation. In the ICU, the utility of this method is limited, and other metrics should be considered.