Many high-risk industries have been able to achieve extremely high levels of reliability and safety. Examples such as the nuclear industry, aviation industry, air traffic control systems and so on, have achieved well over 99.9% reliability levels in critical processes – a failure rate of 1 in 1,000,000 or less. Other industries, however, achieve far lower levels of reliability. So, what explains or accounts for such differences? 

There are recognised strategies that can predictability support reliability, but each has a limit of effectiveness. For example, knowledgeable and skilful individuals and teams who try to remember the right thing to do, will achieve a certain level of reliability, which the research suggests is around the 80% level. So, as far as reliability goes, memory alone is a relatively weak tool. Similarly, diligence/vigilance is another strategy used to boost reliability, but it too has a ceiling of around 90%. An example of this might be a period (a week or a month) highlighting the need for some specific action. During such times, results are higher, but so too is the energy and resources needed, making the strategy unsustainable in the long term. To attain the highest levels of reliability (such as those achieved by the high-risk industries mentioned) we need to consider what is called human factor science (HFS). This is a fascinating but very broad area of study and consequently we will just briefly discuss some of the main principles and how they might apply to dentistry. 

What is human factor science? 

Human factor science is the study of factors that impact on human performance, both positive and negative, and strategies to increase reliability arising from that understanding. The World Health Organisation (WHO) define human factors as the study of all the factors that make it easier to do the work in the right way. The study of HFS can be broken down into two broad areas: ‘people’ and ‘processes/systems’ factors. 

People factors  

As we discussed in Part one of this series, humans are fallible. Some of the people factors that can impede human performance include stress (leading to perceptual deficits and reduced cognitive ability or bandwidth); fatigue (both physical and decisional); poor interpersonal communication; and a poor understanding of human error. Our own attitudes and behaviours can vary from day to day, which may result in our knowledge and skills being inconsistently applied – for instance, we may be distracted or preoccupied. Similarly, people can have different attitudes to things such as clinical risk management or a willingness to follow checklists. We may be predisposed to behave in certain ways depending on our roles, personality traits, and our learning styles. For example, a new or junior dental nurse may feel more reluctant or less predisposed to speak up to the practice principal than a senior associate.

HALT 

We are all susceptible to performance drops due to being any (or all) of the following: hungry, angry, late, or tired (HALT). Research has shown the importance of clinicians looking after themselves (including being adequately hydrated and fed) to be able to deliver the best care for their patients.¹ In part one we discussed how fatigue and tiredness affect our cognition and behaviour. An interesting medical study looking at this is Coen et al Evaluating fitness to perform in surgical residents after night shifts and alcohol intoxication: The development of a Fit-to-Perform test.² 

Ultimately, however, even with all people factors considered, humans will always make mistakes, so further considerations are needed in the form of processes and systems. 

Processes and systems 

Design of processes and systems can make errors less likely to happen and can enhance performance. Outside of dentistry, an example might be engineers ‘designing out’ the problem of people inadvertently putting petrol in diesel cars (and vice versa) by changing the nozzle head sizes.

Equally, processes and systems factors can potentially impede human performance, especially when there is inadequate structured decisional support and checking tools, inadequate measurement, feedback and accountability mechanisms, inadequate huddles and simulation, inadequate environmental design and control, and inadequate equipment. 

In the dental clinic, this could be computer hardware/software issues leading to difficulty in accessing patient records and/or digital radiographs; technology issues e.g., the intra-oral scanner/system not working, or the monitor that you normally use during the consenting process being unavailable.

It could even be something as simple as the air conditioning not working, leaving you feeling hot and bothered. 

It is important to appreciate, however, that to achieve high levels of reliability, it requires consideration of both areas of human factor science – people, and processes and systems. There is a powerful interplay between both sets of factors in attaining high reliability. The best designed processes and systems can be undermined by the people using them, and similarly, ‘good’ people can mask poor processes and systems…until of course, those very people are not available. 

References 

1 Brennan et al, ‘Looking after ourselves at work: the importance of being hydrated and fed’, BMJ 2019; 364: l528 

2 Coen et al, J Surg Educ 2018 Jul-Aug:75(4):968-977