The law states that the alternate solution shall be identified if a harmonized standard is not applied. So, if EN 60601-1:2006 is the harmonized standard, and the alternate solution is not identified, it is a valid non-conformity.
If EN 60601-1:2006 is the harmonized standard, and EN 60601-1:1990/A2:1995 is identified as the alternate solution, it is OK as long as the new items in EN 60601-1:2005 are identified and explained as being not important.
Unfortunately this means you still need to know the detail in latest standard and need some kind of record that it has been reviewed and is not significant for your particular device.
For example, in the old standard, one of the tests for patient support used only patient's weight, not the full weight of the system being supported (e.g. the top part of the table). It was wrong, and this mistake has now has been corrected in the 2006 edition. If that test is applicable to your device, it's hard to argue that EN 60601-1:1990 is an appropriate "alternate solution".
So can't avoid a clause by clause check. The alternate solutions need to be offered for each individual clause. You cannot ignore the whole standard and say the alternate solution is the older standard.
If EN 60601-1:2006 is the harmonized standard, and EN 60601-1:1990/A2:1995 is identified as the alternate solution, it is OK as long as the new items in EN 60601-1:2005 are identified and explained as being not important.
Unfortunately this means you still need to know the detail in latest standard and need some kind of record that it has been reviewed and is not significant for your particular device.
For example, in the old standard, one of the tests for patient support used only patient's weight, not the full weight of the system being supported (e.g. the top part of the table). It was wrong, and this mistake has now has been corrected in the 2006 edition. If that test is applicable to your device, it's hard to argue that EN 60601-1:1990 is an appropriate "alternate solution".
So can't avoid a clause by clause check. The alternate solutions need to be offered for each individual clause. You cannot ignore the whole standard and say the alternate solution is the older standard.