You are wise to phrase your questions about how you communicate what can be a complex decisions. As I'm a Fellow of the CIPD, I've gone along to several recent meetings addressed by specialsits in employment law, on this matter. In my opinion, a sound way of communicating your opinion is to use a rating scale about specific risks you identify in relation to particular tasks and jobs. So, you can indicate your opinioin about 'fitness to work' indirectly by giving a rating of 1 to indicate a high level of risk (and by implication low level of fitness for the particular tasks/job), a rating of 5 to indicate a low level of risk (and high level of fitness for work) and so on. Sensitive use of such a rating scale also enables you to manage challenges about the 'personal characteristics' especially of disability, which can be a serious problem in view of the absence of a ceiling on penalities for unfair discrimation about disability and of some other personal characteristics. This approach also enables you to gradually educate and conduct dialogue with HR, other managers and employess about the risks you address. In situations where you indicate a serious of high level risks, you also can use the data to direct attention of policy makers to matters where some investment may be needed to reduce exposure of existing employees to situational risks.