PMAs are significant undertakings and should not be embarked on lightly. They are likely to take many years to complete and require a committed, ongoing, appropriately staffed and adequately funded Secretariat. Once the PMA collaborative group is formed (see Section 19.2) resources are needed to ensure the ongoing commitment of the group over many years, usually a much longer time period than is required for a retrospective IPD review (see Chapter 18). The Secretariat will be required to organize regular teleconferences, face-to-face meetings (at least annually), newsletters, update contact details and implement other mechanisms to keep the collaborative group together. This type of activity is akin to that undertaken by the co-ordinating centre of a multicentre randomized trial. A benefit of these Secretariat activities is that they often help facilitate adherence to the PMA protocol and encourage complete follow-up within individual participating trials.