Last month more than 700 patients in Glasgow - including those with cancer needing chemotherapy - had their appointments cancelled due to a major IT failure which left NHS staff unable to access their records.
An independent review of the incident, commissioned by NHS Greater Glasgow and Clyde and the Scottish Government, has found that the source of the problem was linked to a rare corruption in an IT programme known as Active Directory.
But experts said the exact root cause of this failure had yet to be determined.
Active Directory is a common part of IT systems, used by the vast majority of organisations and businesses in the UK.
It is used to manage how computer users are given access to the different IT services they have permission to use in their organisation.
When the system went down in Glasgow over two days last month, doctors and other health staff were unable to access patient records or information such as X-rays and scans, meaning many appointments had to be postponed until the information was available.
The review team, led by Scottish Government chief technology officer Andy McClintock, found that the health board had implemented and managed the Active Directory system well and in line with good practice for the industry.
The report praised the board’s IT team for their software suppliers for their professional handling of the incident.
The experts said that no data had been lost and all the actions taken to try to resolve the issues were in line with best practice.
The report said that all those interviewed as part of the review, including Active Directory supplier Microsoft, had never experienced a failure like that seen with the software.
But despite the rarity of the situation, the report said the board already had plans in place to deal with such a scenario. These procedures were used to help recover the system, as set out in their disaster recovery plans.
The report made eight recommendations to further strengthen the IT system which the board has either implemented already or is in the process of introducing.
Health Secretary Alex Neil said: “This review has shown that the technical team took the appropriate actions and did everything possible to restore services under enormous pressure.
“A number of recommendations have come from this review and I note that NHS Greater Glasgow and Clyde are taking steps these to implement all of the recommendations promptly.
“I am keen that lessons can be learnt across Scotland and the report has also been shared with the technical leads in all other health boards.
“I have also instructed a robust review right across the health service in Scotland with all NHS boards ensuring that both their IT systems and their backup systems are robust. This review will report back to me by the end of the year.”
Robert Calderwood, chief executive of NHS Greater Glasgow and Clyde, said: “I am pleased that the review team were able to satisfy themselves that NHSGGC’s IT infrastructure is sound and well managed and that the fault was not one that could have been foreseen.
“The recommendations made in the report will be implemented in full and a number have already been completed.
“709 patients had their appointment temporarily postponed due to this issue and although I apologised at the time I would like to reiterate my apologies for the inconvenienced this caused.
“I would also wish to thank staff for the remarkable resilience shown by the organisation as a whole in ensuring that more than 10,000 patients continued to be seen using manual backup systems whilst the problem was ongoing.”